Slides Flow Measurement Seminar

Industrial Flow Measurement Seminar Presented by David W. Spitzer Spitzer and Boyes, LLC Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

Disclaimer ƒ The content of this seminar was developed in an impartial manner from information provided by suppliers ƒ Discrepancies noted and brought to the attention of the presenter will be corrected ƒ We do not endorse, favor, or disfavor any particular supplier or their equipment Spitzer and Boyes, LLC Copperhill and Pointer, Inc. Seminar Presenter Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Seminar Outline ƒ Introduction ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Introduction ƒ Working Definition of a Process ƒ Why Measure Flow?

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Working Definition of a Process ƒ A process is anything that changes

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Why Measure Flow? ƒ Flow measurements provide information about the process ƒ The information that is needed depends on the process

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Why Measure Flow? ƒ Custody transfer ƒ Measurements are often required to determine the total quantity of fluid that passed through the flowmeter for billing purposes

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Why Measure Flow? ƒ Monitor the process ƒ Flow measurements can be used to ensure that the process is operating satisfactorily

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Why Measure Flow? ƒ Improve the process ƒ Flow measurements can be used for heat and material balance calculations that can be used to improve the process

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Why Measure Flow? ƒ Monitor a safety parameter ƒ Flow measurements can be used to ensure that critical portions of the process operate safely

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Seminar Outline ƒ Introduction

ƒ Fluid Flow Fundamentals ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Fluid Flow Fundamentals ƒ Temperature ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Pressure Density and Fluid Expansion Types of Flow Inside Pipe Diameter Viscosity Reynolds Number and Velocity Profile Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Temperature ƒ Measure of relative hotness/coldness ƒ Water freezes at 0°C (32°F) ƒ Water boils at 100°C (212°F)

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Temperature ƒ Removing heat from fluid lowers temperature ƒ If all heat is removed, absolute zero temperature is reached at approximately -273°C (-460°F)

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Temperature ƒ Absolute temperature scales are relative to absolute zero temperature ƒ Absolute zero temperature = 0 K (0°R) ƒ Kelvin = °C + 273 ƒ ° Rankin = °F + 460

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Temperature ƒ Absolute temperature is important for flow measurement

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Temperature 373 K = 100°C 273 K = 0°C

0 K = -273°C

672°R = 212°F 460°R = 0°F

0°R = -460°F

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Temperature Problem ƒ The temperature of a process increases from 20°C to 60°C. For the purposes of flow measurement, by what percentage has the temperature increased? Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Temperature ƒ It is tempting to answer that the temperature tripled (60/20), but the ratio of the absolute temperatures is important for flow measurement ƒ (60+273)/(20+273) = 1.137 ƒ 13.7% increase Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Fluid Flow Fundamentals ƒ Temperature

ƒ Pressure ƒ ƒ ƒ ƒ ƒ ƒ

Density and Fluid Expansion Types of Flow Inside Pipe Diameter Viscosity Reynolds Number and Velocity Profile Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Pressure ƒ Pressure is defined as the ratio of a force divided by the area over which it is exerted (P=F/A)

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Pressure Problem ƒ What is the pressure exerted on a table by a 2 inch cube weighing 5 pounds? ƒ (5 lb) / (4 inch2) = 1.25 lb/in2 ƒ If the cube were balanced on a 0.1 inch diameter rod, the pressure on the table would be 636 lb/in2 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Pressure ƒ Atmospheric pressure is caused by the force exerted by the atmosphere on the surface of the earth ƒ 2.31 feet WC / psi ƒ 10.2 meters WC / bar

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Pressure ƒ Removing gas from a container lowers the pressure in the container ƒ If all gas is removed, absolute zero pressure (full vacuum) is reached at approximately -1.01325 bar (-14.696 psig)

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Pressure ƒ Absolute pressure scales are relative to absolute zero pressure ƒ Absolute zero pressure ƒ Full vacuum = 0 bar abs (0 psia) ƒ bar abs = bar + 1.01325 ƒ psia = psig + 14.696

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Pressure Absolute

Gauge Differential

Atmosphere Vacuum

Absolute Zero

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Pressure ƒ Absolute pressure is important for flow measurement

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Pressure Problem ƒ The pressure of a process increases from 1 bar to 3 bar. For the purposes of flow measurement, by what percentage has the pressure increased? Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Pressure ƒ It is tempting to answer that the pressure tripled (3/1), but the ratio of the absolute pressures is important for flow measurement ƒ (3+1.01325)/(1+1.01325) = 1.993 ƒ 99.3% increase Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Fluid Flow Fundamentals ƒ Temperature ƒ Pressure

ƒ Density and Fluid Expansion ƒ ƒ ƒ ƒ ƒ

Types of Flow Inside Pipe Diameter Viscosity Reynolds Number and Velocity Profile Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ Density is defined as the ratio of the mass of a fluid divided its volume (ρ=m/V)

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Density and Fluid Expansion ƒ Specific Gravity of a liquid is the ratio of its operating density to that of water at standard conditions ƒ SG = ρ liquid / ρ water at standard conditions

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Density and Fluid Expansion Problem ƒ What is the density of air in a 3.2 ft3 filled cylinder that has a weight of 28.2 and 32.4 pounds before and after filling respectively?

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Density and Fluid Expansion ƒ The weight of the air in the empty cylinder is taken into account ƒ Mass =(32.4-28.2)+(3.2•0.075) = 4.44 lb ƒ Volume = 3.2 ft3 ƒ Density = 4.44/3.2 = 1.39 lb/ft3 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ The density of most liquids is nearly unaffected by pressure ƒ Expansion of liquids ƒ V = V0 (1 + β•ΔT) ƒ V = new volume ƒ V0 = old volume ƒ β = cubical coefficient of expansion ƒ ΔT = temperature change Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion Problem ƒ What is the change in density of a liquid caused by a 10°C temperature rise where β is 0.0009 per °C ?

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Density and Fluid Expansion ƒ Calculate the new volume ƒ V = V0 (1 + 0.0009•10) = 1.009 V0 ƒ The volume of the liquid increased to 1.009 times the old volume, so the new density is (1/1.009) or 0.991 times the old density

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Density and Fluid Expansion ƒ Expansion of solids ƒ V = V0 (1 + β•ΔT) ƒ where β = 3•α ƒ α = linear coefficient of expansion

ƒ Temperature coefficient ƒ Stainless steel temperature coefficient is approximately 0.5% per 100°C Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion Problem ƒ What is the increase in size of metal caused by a 50°C temperature rise where the metal has a temperature coefficient of 0.5% per 100°C ?

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Density and Fluid Expansion ƒ Calculate the change in size ƒ (0.5 • 50) = 0.25% ƒ Metals (such as stainless steel) can exhibit significant expansion

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Density and Fluid Expansion ƒ Boyle’s Law states the the volume of an ideal gas at constant temperature varies inversely with absolute pressure ƒV=K/P

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Density and Fluid Expansion ƒ New volume can be calculated ƒV = K / P ƒ V0 = K / P0

ƒ Dividing one equation by the other yields ƒ V/V0 = P0 / P Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion Problem ƒ How is the volume of an ideal gas at constant temperature and a pressure of 28 psig affected by a 5 psig pressure increase?

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Density and Fluid Expansion ƒ Calculate the new volume ƒ V/V0 = (28+14.7) / (28+5+14.7) = 0.895 ƒ V = 0.895 V0 ƒ Volume decreased by 10.5%

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Density and Fluid Expansion ƒ Charles’ Law states the the volume of an ideal gas at constant pressure varies directly with absolute temperature ƒV=K•T

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Density and Fluid Expansion ƒ New volume can be calculated ƒV = K • T ƒ V0 = K • T0

ƒ Dividing one equation by the other yields ƒ V/V0 = T / T0 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion Problem ƒ How is the volume of an ideal gas at constant pressure and a temperature of 15ºC affected by a 10ºC decrease in temperature?

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Density and Fluid Expansion ƒ Calculate the new volume ƒ V/V0 = (273+15-10) / (273+15) = 0.965 ƒ V = 0.965 V0 ƒ Volume decreased by 3.5%

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Density and Fluid Expansion ƒ Ideal Gas Law combines Boyle’s and Charles’ Laws ƒ PV = n R T

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Density and Fluid Expansion ƒ New volume can be calculated ƒP • V = n • R • T ƒ P0 • V0 = n • R • T0

ƒ Dividing one equation by the other yields ƒ V/V0 = (P0 /P) • (T / T0) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion Problem ƒ How is the volume of an ideal gas at affected by a 10.5% decrease in volume due to temperature and a 3.5% decrease in volume due to pressure? Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ Calculate the new volume ƒ V/V0 = 0.895 • 0.965 = 0.864 ƒ V = 0.864 V0 ƒ Volume decreased by 13.6%

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Density and Fluid Expansion ƒ Non-Ideal Gas Law takes into account non-ideal behavior ƒ PV = n R T Z

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Density and Fluid Expansion ƒ New volume can be calculated ƒP • V = n • R • T • Z ƒ P0 • V0 = n • R • T0 • Z0

ƒ Dividing one equation by the other yields ƒ V/V0 = (P0 /P) • (T / T0) • (Z / Z0) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ For liquids, specific gravity is the ratio of the density of the liquid to the density of water at standard conditions

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Density and Fluid Expansion ƒ For gases, specific gravity is the ratio of the density of the gas to the density of air at standard conditions ƒ Specific gravity is commonly used to describe the ratio of the density of the gas at standard conditions to the density of air at standard conditions Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ Standard conditions ƒ Pressure ƒ 14.696 psia, 1 atmosphere ƒ 14.7 psia ƒ 14.4 psia ƒ 1 bar absolute ƒ 4 oz. Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Density and Fluid Expansion ƒ Standard conditions ƒ Temperature ƒ 15°C (59°F) ƒ 68°F ƒ 70°F ƒ 0°C

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Fluid Flow Fundamentals ƒ Temperature ƒ Pressure ƒ Density and Fluid Expansion

ƒ Types of Flow ƒ ƒ ƒ ƒ

Inside Pipe Diameter Viscosity Reynolds Number and Velocity Profile Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Types of Flow ƒ Q=A•v ƒ Q is the volumetric flow rate ƒ A is the cross-sectional area of the pipe ƒ v is the average velocity of the fluid in the pipe

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Types of Flow ƒ Typical Volumetric Flow Units(Q = A • v) ƒ ƒ ƒ ƒ ƒ

ft2 • ft/sec = ft3/sec m2 • m/sec = m3/sec gallons per minute (gpm) liters per minute (lpm) cubic centimeters per minute (ccm)

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Types of Flow ƒ W=ρ•Q ƒ W is the mass flow rate ƒ ρ is the fluid density ƒ Q is the volumetric flow rate

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Types of Flow ƒ Typical Mass Flow Units (W = ρ • Q) ƒ ƒ ƒ ƒ ƒ

lb/ft3 • ft3/sec = lb/sec kg/m3 • m3/sec = kg/sec standard cubic feet per minute (scfm) standard liters per minute (slpm) standard cubic centimeters per minute(sccm)

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Types of Flow ƒ Q=A•v ƒ W=ρ•Q ƒ ƒ ƒ ƒ

Q W v ½ ρv2

volumetric flow rate mass flow rate fluid velocity inferential flow rate

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Fluid Flow Fundamentals ƒ ƒ ƒ ƒ

Temperature Pressure Density and Fluid Expansion Types of Flow

ƒ Inside Pipe Diameter ƒ Viscosity ƒ Reynolds Number and Velocity Profile ƒ Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Inside Pipe Diameter ƒ The inside pipe diameter (ID) is important for flow measurement ƒ Pipes of the same size have the same outside diameter (OD) ƒ Welding considerations

ƒ Pipe wall thickness, and hence its ID, is determined by its schedule Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Inside Pipe Diameter ƒ Pipe wall thickness increases with increasing pipe schedule ƒ Schedule 40 pipes are considered “standard” wall thickness ƒ Schedule 5 pipes have thin walls ƒ Schedule 160 pipes have thick walls Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Inside Pipe Diameter ƒ Nominal pipe size ƒ For pipe sizes 12-inch and smaller, the nominal pipe size is the approximate ID of a Schedule 40 pipe ƒ For pipe sizes 14-inch and larger, the nominal pipe size is the OD of the pipe

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Fluid Flow Fundamentals ƒ ƒ ƒ ƒ ƒ

Temperature Pressure Density and Fluid Expansion Types of Flow Inside Pipe Diameter

ƒ Viscosity ƒ Reynolds Number and Velocity Profile ƒ Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Viscosity ƒ Viscosity is the ability of the fluid to flow over itself ƒ Units ƒ cP, cSt ƒ Saybolt Universal (at 100ºF, 210 ºF) ƒ Saybolt Furol (at 122ºF, 210 ºF) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Viscosity ƒ Viscosity can be highly temperature dependent ƒ Water ƒ Honey at 40°F, 80°F, and 120°F ƒ Peanut butter

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Viscosity ƒ At a given temperature: ƒ Newtonian fluids have constant viscosity ƒ the viscosity of a Non-Newtonian fluid varies when different amounts of sheer stress is applied

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Viscosity ƒ Stress versus Flow Curves Ideal Plastic

Thixotropic

Newtonian

Inverted Plastic

Stress

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Fluid Flow Fundamentals ƒ ƒ ƒ ƒ ƒ ƒ

Temperature Pressure Density and Fluid Expansion Types of Flow Inside Pipe Diameter Viscosity

ƒ Reynolds Number and Velocity Profile ƒ Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Velocity Profile and Reynolds Number ƒ Reynolds number is the ratio of inertial forces to viscous forces in the flowing stream ƒ RD = 3160 • Q gpm • SG / (μcP • Din)

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Velocity Profile and Reynolds Number ƒ Reynolds number can be used as an indication of how the fluid is flowing in the pipe ƒ Flow regimes based on RD ƒ Laminar ƒ Transitional ƒ Turbulent

< 2000 2000 - 4000 > 4000

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Velocity Profile and Reynolds Number ƒ Not all molecules in the pipe flow at the same velocity ƒ Molecules near the pipe wall move slower; molecules in the center of the pipe move faster

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Velocity Profile and Reynolds Number ƒ Laminar Flow Regime ƒ Molecules move straight down pipe

Velocity Profile Flow

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Velocity Profile and Reynolds Number ƒ Turbulent Flow Regime ƒ Molecules migrate throughout pipe

Velocity Profile Flow

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Velocity Profile and Reynolds Number ƒ Transitional Flow Regime ƒ Molecules exhibit both laminar and turbulent behavior

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Velocity Profile and Reynolds Number ƒ Many flowmeters require a good velocity profile to operate accurately ƒ Obstructions in the piping system can distort the velocity profile ƒ Elbows, tees, fittings, valves

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Velocity Profile and Reynolds Number ƒA distorted velocity profile can introduce significant errors into the measurement of most flowmeters Velocity Profile (distorted)

Flow

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Velocity Profile and Reynolds Number ƒ Good velocity profiles can be developed ƒ Straight run upstream and downstream ƒ No fittings or valves ƒ Upstream is usually longer and more important

ƒ Flow conditioner

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Velocity Profile and Reynolds Number ƒ Good velocity profiles can be developed ƒ Locate control valve downstream of flowmeter ƒ Upstream control valve should be a warning that all aspects of the flow measurement system should be checked carefully

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Velocity Profile and Reynolds Number

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Velocity Profile and Reynolds Number

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Velocity Profile and Reynolds Number

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Fluid Flow Fundamentals ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Temperature Pressure Density and Fluid Expansion Types of Flow Inside Pipe Diameter Viscosity Reynolds Number and Velocity Profile

ƒ Hydraulic Phenomena Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Hydraulic Phenomena ƒ Vapor pressure is defined as the pressure at which a liquid and its vapor can exist in equilibrium ƒ The vapor pressure of water at 100°C is atmospheric pressure (1.01325 bar abs) because water and steam can coexist

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Hydraulic Phenomena ƒ A saturated vapor is in equilibrium with its liquid at its vapor pressure ƒ Saturated steam at atmospheric pressure is at a temperature of 100°C

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Hydraulic Phenomena ƒ A superheated vapor is a saturated vapor that is at a higher temperature than its saturation temperature ƒ Steam at atmospheric pressure that is at 150°C is a superheated vapor with 50°C of superheat

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Hydraulic Phenomena ƒ Flashing is the formation of gas (bubbles) in a liquid after the pressure of the liquid falls below its vapor pressure ƒ Reducing the pressure of water at 100°C below atmospheric pressure (say 0.7 bar abs) will cause the water to boil

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92

Hydraulic Phenomena ƒ Cavitation is the formation and subsequent collapse of gas (bubbles) in a liquid after the pressure of the liquid falls below and then rises above its vapor pressure ƒ Can cause severe damage in pumps and valves

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31

Hydraulic Phenomena Vapor Pressure (typical)

Pressure

Flashing Cavitation

Distance Piping Obstruction Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

94

Hydraulic Phenomena ƒ Energy Considerations ƒ Claims are sometimes made that flowmeters with a lower pressure drop will save energy

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95

Hydraulic Phenomena ƒ Energy Considerations Centrifugal Pump Curve

Pressure

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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32

Hydraulic Phenomena ƒ Energy Considerations

System Curve (without flowmeter)

Pressure

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Hydraulic Phenomena ƒ Energy Considerations

Pressure

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

98

Hydraulic Phenomena ƒ Energy Considerations

System and Flowmeter

System, Flowmeter and Control Valve System

P Pressure

Flowmeter and Control Valve Pressure Drop

Q

Flow

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99

33

Hydraulic Phenomena ƒ Energy Considerations

System and Flowmeter (Low Pressure Drop)

System, Flowmeter and Control Valve System

P Pressure

Flowmeter and Control Valve Pressure Drop

Q

Flow

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100

Hydraulic Phenomena ƒ Energy Considerations ƒ The pump operates at the same flow and pressure, so no energy savings are achieved by installing a flowmeter with a lower pressure drop

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101

Hydraulic Phenomena ƒ Energy Considerations Full Speed

System and Flowmeter

System

P Pressure

Reduced Speed

Q

Flow

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34

Hydraulic Phenomena ƒ Energy Considerations ƒ Operating the pump at a reduced speed generates the same flow but requires a lower pump discharge pressure ƒ Hydraulic energy generated by the pump better matches the load ƒ Energy savings are proportional to the cube of the speed

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103

Seminar Outline ƒ Introduction ƒ Fluid Flow Fundamentals

ƒ Performance Measures ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

104

Performance Measures ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Performance Criteria Performance Statements Repeatability Linearity Accuracy Composite Accuracy Turndown Rangeability Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

105

35

Performance Criteria ƒ ƒ ƒ ƒ ƒ

Installation complexity and cost Maintenance Accuracy Linearity Repeatability

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106

Performance Criteria ƒ Dependence on fluid properties ƒ Hydraulic considerations of flowmeter ƒ Hydraulic considerations of fluid ƒ Operating Costs ƒ Reliability ƒ Safety Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

107

Performance Statements ƒ Percent of rate ƒ Percent of full scale ƒ Percent of meter capacity (upper range limit) ƒ Percent of calibrated span

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108

36

Performance Statements ƒ 1% of rate performance at different flow rates with a 0-100 unit flow range ƒ ƒ ƒ ƒ

100% flow Æ 0.01•100 50% flow Æ 0.01•50 25% flow Æ 0.01•25 10% flow Æ 0.01•10

1.00 unit 0.50 unit 0.25 unit 0.10 unit

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109

Performance Statements 10 %Rate 0 Error

1% Rate Performance Flow

-10

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110

Performance Statements ƒ 1% of full scale performance at different flow rates with a 0-100 unit flow range ƒ ƒ ƒ ƒ

100% flow Æ 0.01•100 50% flow Æ 0.01•100 25% flow Æ 0.01•100 10% flow Æ 0.01•100

1 unit = 1% rate 1 unit = 2% rate 1 unit = 4% rate 1 unit = 10% rate

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111

37

Performance Statements 1% Full Scale Performance

10 %Rate 0 Error

Flow

-10

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

Performance Statements ƒ 1% of meter capacity (or upper range limit) performance at different flow rates with a 0-100 unit flow range (URL=400) ƒ ƒ ƒ ƒ

100% flow Æ 0.01•400 50% flow Æ 0.01•400 25% flow Æ 0.01•400 10% flow Æ 0.01•400

4 units = 4% rate 4 units = 8% rate 4 units = 16% rate 4 units = 40% rate

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113

Performance Statements 10

0

1% Meter Capacity Performance

Flow

-10

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38

Performance Statements ƒ Performance expressed as a percent of calibrated span is similar to full scale and meter capacity statements where the absolute error is a percentage of the calibrated span

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115

Performance Statements ƒ 1% of calibrated span performance at different flow rates with a 0-100 unit flow range (URL=400, calibrated span=200) ƒ ƒ ƒ ƒ

100% flow Æ 0.01•200 50% flow Æ 0.01•200 25% flow Æ 0.01•200 10% flow Æ 0.01•200

2 units = 2% rate 2 units = 4% rate 2 units = 8% rate 2 units = 20% rate

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116

Performance Statements 10

0

1% of Calibrated Span Performance (assuming 50% URL) Flow

-10

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39

Performance Statements ƒ A calibrated span statement becomes a full scale statement when the instrument is calibrated to full scale ƒ A calibrated span statement becomes a meter capacity statement when the instrument is calibrated at URL Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

118

Performance Statements ƒ Performance specified as a percent of rate, percent of full scale, percent of meter capacity, and percent of calibrated span are different

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119

Performance Statements 1% Calibrated Span (50%URL)

1% Rate

10

%Rate 0 Error

Flow

-10 1% Full Scale

1% Meter Capacity

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40

Performance Statements ƒ Performance statements can be manipulated because their meaning may not be clearly understood ƒ Technical assistance may be needed to analyze the statements

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121

Repeatability ƒ Repeatability is the ability of the flowmeter to reproduce a measurement each time a set of conditions is repeated

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122

Repeatability Repeatability Error 0

Flow

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41

Linearity ƒ Linearity is the ability of the relationship between flow and flowmeter output (often called the characteristic curve or signature of the flowmeter) to approximate a linear relationship

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124

Linearity Linearity Flow

Error 0

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Accuracy ƒ Accuracy is the ability of the flowmeter to produce a measurement that corresponds to its characteristic curve

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Accuracy Accuracy Flow

Error 0

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Composite Accuracy ƒ Flowmeter suppliers often specify the composite accuracy that represents the combined effects of repeatability, linearity and accuracy

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128

Composite Accuracy Composite Accuracy (in Flow Range) Flow

Error 0

Flow Range

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43

Composite Accuracy

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Composite Accuracy

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Turndown ƒ Performance statements apply over a range of operation ƒ Turndown is the ratio of the maximum flow that the flowmeter will measure within the stated accuracy to the minimum flow that can be measured within the stated accuracy Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Rangeability ƒ Rangeability is a measure of how much the range (full scale) can be adjusted

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133

Seminar Outline ƒ Introduction ƒ Fluid Flow Fundamentals ƒ Performance Measures

ƒ Linearization and Compensation ƒ ƒ ƒ ƒ ƒ ƒ

Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

134

Linearization and Compensation ƒ Linear and nonlinear flowmeters ƒ Gas density compensation ƒ Pressure ƒ Temperature ƒ Tap location

ƒ Liquid temperature compensation ƒ Flow computers Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Linear Flowmeters

% Flow Signal

Linear Output Signal

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Nonlinear Flowmeters

% Flow Signal

Squared Output Signal

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Linear and Nonlinear Flowmeters Output 1% 10 % 25 % 50 % 100 %

Linear Flowmeter 1% 10 % 25 % 50 % 100 %

Nonlinear Flowmeter 10 % 31.6 % 50 % 70.7 % 100 %

* Note the large gain at low flows for nonlinear flowmeters Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

138

46

Gas Density Compensation Range of Operation Pressure

Nominal Conditions

Standard Conditions Temperature Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

139

Gas Density Compensation Flowmeter Factors Pressure

Nominal Conditions

Standard Conditions Temperature Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

140

Gas Density Compensation Compensation Pressure

Actual Conditions Nominal Conditions

Standard Conditions Temperature Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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47

Gas Density Compensation ƒ ƒ ƒ ƒ

Gas Laws Laboratory data Handbook information Mathematical relationship ƒ Typically a function of pressure, temperature, and composition)

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142

Gas Density Compensation ƒ Gas Laws

V nom =

(P • T nom • Z nom) • V ------------------(Pnom • T • Z)

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143

Gas Density Compensation ƒ Gas Laws

P V nom = constant • -------- • V (T • Z)

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Gas Density Compensation ƒ Effects can be large (see table in text) ƒ Temperature ƒ 1% per 3°C

at 300K

ƒ Pressure ƒ 10% per bar ƒ 1% per psi

at 9 bar (gauge) at 85 psig

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145

Gas Density Compensation ƒ Density affects the output of squared output flowmeters approximately half as much as linear output flowmeters ƒ Pressure effects are lower for squared output flowmeters ƒ Temperature effects are lower for squared output flowmeters

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146

Liquid Density Compensation ƒ Typically temperature correction

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147

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Pressure Tap Location ƒ Pressure tap ƒ Usually upstream ƒ May be in the flowmeter body ƒ Some flowmeters allow downstream

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148

Pressure Tap Location ƒ Temperature tap ƒ Usually downstream to reduce turbulence ƒ Upstream temperature tap should be a warning that all aspects of the flow measurement system should be checked carefully

ƒ May be within the flowmeter body

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149

Flow Computers ƒ Density compensation ƒ Pressure, temperature, and compressibility

ƒ Reynolds number compensation ƒ Flowmeter expansion ƒ Other…

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150

50

Seminar Outline ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation

ƒ Totalization ƒ ƒ ƒ ƒ ƒ

Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

151

Analog Flowmeter (Linear)

% Flow Signal

Output Proportional to Flow

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

152

Analog Flowmeter (Nonlinear)

% Flow Signal

Output Proportional to Square of Flow

Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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51

Digital Flowmeter (Linear)

% Flow Signal

Output Proportional to Flow Flowmeter may turn off at low flows Flow

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154

Totalization ƒ Analog flowmeter ƒ Integrator (0.5% rate performance) ƒ Indicator (optional)

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155

Totalization ƒ Digital flowmeter ƒ Count pulses (±1 pulse) ƒ f/I converter (0.5% rate) and indicator (optional)

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156

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Totalization ƒ Digital flowmeter with analog output ƒ Inherent flowmeter performance ƒ Analog output circuit ƒ Add approximately 0.06% of full scale

ƒ f/I converter (0.5% rate) and indicator

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157

Totalization ƒ Digital flowmeters seem to be superior to analog flowmeter ƒ Inherent performance may not be equal ƒ Digital flowmeters generally turn off at flow flow rates ƒ Analog output circuit ƒ Add approximately 0.06% of full scale

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158

Seminar Outline ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization

ƒ Flowmeter Calibration ƒ ƒ ƒ ƒ

Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

159

53

Calibration ƒ Calibration is performing adjustments to the instrument so that it measures within accuracy constraints ƒ Comparison of measurement with “true” value

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160

Flowmeter Calibration ƒ Calibration of many variables is static ƒ Level – tape, ruler ƒ Pressure – force and area ƒ Temperature – freezing/boiling water

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161

Flowmeter Calibration ƒ Calibration of flowmeters is dynamic ƒ Primary standard uses time and weight

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162

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Flowmeter Calibration ƒ Ideally, flowmeter calibration should be performed under operating conditions ƒ Usually not practical and often impossible ƒ Use another calibration technique as a surrogate

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163

Flowmeter Calibration ƒ Wet calibration ƒ Primary flow laboratory ƒ Flow calibration facility

ƒ Dry calibration ƒ Physical dimensions ƒ Electronic techniques

ƒ Verification of operation Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

164

Primary Flowmeter Laboratory Meter Under Test

Diverter Valve

Water Tank

Weigh Tank Load Cells

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Primary Flowmeter Laboratory Diverter Valve Meter Under Test

Weigh Tank

Water Tank

Load Cells Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

166

Primary Flowmeter Laboratory Meter Under Test

Diverter Valve

Weigh Tank

Water Tank

Load Cells Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

167

Flow Calibration Facility Meter Under Test Master Meter

Water Tank

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

Production Meters

168

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Dry Calibration ƒ Dry calibration ƒ Verify physical dimensions ƒ Electronic techniques ƒ Zero ƒ Span ƒ Scaling factor ƒ Analog output

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

169

Effect of Zero Calibration Ideal Calibration % Flow Signal

Effect of 1% Zero Calibration Error (1% of full scale) Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

170

Effect of Span Calibration Ideal Calibration % Flow Signal

Effect of 1% Span Calibration Error (1% of rate) Flow Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

171

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Calibration ƒ Instruments with zero and span adjustments tend to have percent of full scale accuracy ƒ Instruments with a span adjustment and no zero adjustment tend to have percent of rate accuracy ƒ There are exceptions Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

172

Seminar Outline ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration

ƒ Measurement of Flowmeter Performance ƒ Miscellaneous Considerations ƒ Flowmeter Technologies ƒ Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

173

Measurement of Flowmeter Performance ƒ Flow measurement system components ƒ Flow range ƒ Flowmeter ƒ Transmitter

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58

Measurement of Flowmeter Performance ƒ Flow measurement system components ƒ ƒ ƒ ƒ

Linearization Digital conversion Indicator Totalization

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

175

Measurement of Flowmeter Performance ƒ Overall flow measurement system performance ƒ Combine components statistically (do not add mathematically) ƒ Accuracy ƒ Uncertainty (ISO GUM)

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

176

Seminar Outline ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance

ƒ Miscellaneous Considerations ƒ Flowmeter Technologies ƒ Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Miscellaneous Considerations ƒ Materials of construction ƒ ƒ ƒ ƒ ƒ

Corrosion Abrasion/erosion Pressure and temperature Flange ratings Contamination

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178

Miscellaneous Considerations ƒ Velocity profile ƒ Straight run ƒ Reductions up/downstream of straight run ƒ Flanges are part of straight run ƒ Remove internal welding beads

ƒ Align gaskets so they do not intrude into pipe ƒ Align flowmeter so it is centered in the pipe

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179

Miscellaneous Considerations ƒ Velocity profile ƒ ƒ ƒ ƒ

Flow conditioner Control valve downstream Temperature tap downstream Pressure tap upstream

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Miscellaneous Considerations ƒ Piping considerations ƒ Orientation ƒ Full pipe ƒ Single phase flow ƒ Homogeneous flow

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181

Miscellaneous Considerations ƒ Piping considerations ƒ Support flowmeter ƒ Do not have flowmeter supporting piping

ƒ Alignment ƒ Axial ƒ Face-to-face ƒ Do not “spring” pipe

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182

Miscellaneous Considerations ƒ Piping considerations ƒ ƒ ƒ ƒ

Bypass piping Hydro-test considerations Dirt Coating

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183

61

Miscellaneous Considerations ƒ Wiring ƒ 2-wire ƒ Signal wires provide loop power

ƒ 3-wire ƒ Extra wire for power

ƒ 4-wire ƒ Separate signal and power wires (in separate conduits unless low voltage power is used) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

184

Miscellaneous Considerations ƒ Safety ƒ Grounding ƒ Required for some flowmeters ƒ Safety consideration for some services (oxygen)

ƒ Leakage ƒ Area electrical classification ƒ Lubricants and contamination Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

185

Seminar Outline ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations

ƒ Flowmeter Technologies ƒ Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

186

62

Flowmeter Technologies ƒ Introduction ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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187

Flowmeter Classes ƒ Wetted moving parts ƒ Positive displacement ƒ Turbine ƒ Variable area

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188

Flowmeter Classes ƒ Wetted with no moving parts ƒ ƒ ƒ ƒ

Differential pressure Oscillatory Target Thermal

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189

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Flowmeter Classes ƒ Obstructionless ƒ Coriolis mass ƒ Magnetic ƒ ultrasonic

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Flowmeter Classes ƒ Non-wetted (external) ƒ Ultrasonic ƒ Correlation

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191

Flowmeter Measurements ƒ Volume ƒ Positive displacement

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Flowmeter Measurements ƒ Velocity ƒ ƒ ƒ ƒ ƒ

Magnetic Oscillatory Turbine Ultrasonic correlation

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193

Flowmeter Measurements ƒ Inferential ƒ Differential pressure ƒ Target ƒ Variable area

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194

Flowmeter Measurements ƒ Mass ƒ Coriolis mass ƒ Thermal

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Flowmeter Technology Sections ƒ Technologies are in alphabetical order ƒ Technology sections have similar organization

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Flowmeter Technologies ƒ Introduction

ƒ Differential Pressure ƒ ƒ ƒ ƒ ƒ ƒ

Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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197

Principle of Operation ƒ A piping restriction is used to develop a pressure drop that is measured and used to infer fluid flow ƒ Primary Flow Element ƒ Transmitter (differential pressure)

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66

Principle of Operation ƒ Bernoulli’s equation states that energy is approximately conserved across a constriction in a pipe ƒ Static energy (pressure head) ƒ Kinetic energy (velocity head) ƒ Potential energy (elevation head)

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199

Principle of Operation ƒ Bernoulli’s equation ƒ P/(ρ•g) + ½v2/g + y = constant P = absolute pressure ρ = density g = acceleration of gravity v = fluid velocity y = elevation Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

200

Principle of Operation ƒ Equation of Continuity ƒ Q = A•v Q = flow (volumetric) A = cross-sectional area v = fluid velocity (average)

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Principle of Operation ƒ Apply the equation of continuity and Bernoulli’s equation for flow in a horizontal pipe ƒ Acceleration of gravity is constant ƒ No elevation change

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202

Principle of Operation ƒ Apply Bernoulli’s equation upstream and downstream of a restriction ƒ P1 + ½ ρ•v12 = P2 + ½ ρ•v22

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203

Principle of Operation ƒ Solve for the pressure difference and use the equation of continuity ƒ (P1 - P2) = ½ ρ•v22 - ½ ρ•v12 = ½ ρ [v22 - v12] = ½ ρ [(A1/A2)2 – 1]•v12 = ½ ρ [(A1/A2)2 – 1]•Q2/A12 = constant • ρ • Q2 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ ΔP = constant • ρ • Q2 ƒ Fluid density affects the measurement ƒ Pressure drop is proportional to the square of the flow rate ƒ Squared output flowmeter ƒ Double the flow… four times the differential

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205

Principle of Operation ƒ Q = constant • (ΔP/ρ)½ ƒ Fluid density affects the measurement ƒ Flow rate is proportional to the square root of the differential pressure produced ƒ Often called “square root flowmeter”

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206

Principle of Operation ƒ Q is proportional to 1/ρ½ ƒ Fluid density affects the measurement by approximately -1/2% per % density change

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Principle of Operation ƒ Liquid density changes are usually small ƒ Gas and vapor density changes can be large and may need compensation for accurate flow measurement ƒ Flow computers ƒ Multivariable differential pressure transmitters Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

208

Principle of Operation Problem ƒ What is the effect on a differential pressure flowmeter when the operating pressure of a gas is increased from 6 to 7 bar? ƒ To simplify calculations, assume that atmospheric pressure is 1 bar abs Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ The ratio of the densities is (7+1)/(6+1) = 1.14 ƒ The density of the gas increased 14 percent

ƒ The flow measurement is proportional to the inverse of the square root of the density which is (1/1.14)½ = 0.94 ƒ The flow measurement will be approximately 6 percent low Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Problem ƒ Calculate the differential pressures produced at various percentages of full scale flow ƒ Assume 0-100% flow corresponds to 0-100 differential pressure units

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211

Principle of Operation Differential pressure as a function of flow Flow ΔP 100 % 100 dp units 50 % 25 “ “ 20 % 4 “ “ 10 % 1 “ “ Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

212

Principle of Operation ƒ Low flow measurement can be difficult ƒ For example, only ¼ of the differential pressure is generated at 50 percent of the full scale flow rate. At 10 percent flow, the signal is only 1 percent of the differential pressure at full scale.

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Principle of Operation Problem ƒ What is the differential pressure turndown for a 10:1 flow range? ƒ 0.12 = 0.01, so at 10% flow the differential pressure is 1/100 of the differential pressure at 100% flow ƒ The differential pressure turndown is 100:1 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ Noise can create problems at low flow rates ƒ 0-10% flow corresponds to 0-1 dp units ƒ 90-100% flow corresponds to 81-100% dp units

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215

Principle of Operation ƒ Noise at low flow rates can be reduced by low flow characterization ƒ Force to zero ƒ Linear relationship at low flow rates

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Principle of Operation ƒ Square root relationship generally applies when operating above the Reynolds number constraint for the primary flow element ƒ Operating below the constraint causes the flow equation to become linear with differential pressure (and viscosity) ƒ Applying the incorrect equation will result in flow measurement error Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

217

Principle of Operation Problem ƒ If the Reynolds number at 100% flow is 10,000, what is the turndown for accurate measurement if the primary flow element must operate in the turbulent flow regime? ƒ 10,000/4000, or 2.5:1 Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

218

Principle of Operation Problem ƒ Will the flowmeter operate at 10% flow? ƒ It will create a differential pressure… however, Reynolds number will be below the constraint, so the flow measurement will not conform to the square root equation (and will not be accurate)

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Orifice Plate Primary Flow Element Orifice Plate Flow

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220

Orifice Plate Primary Flow Elements ƒ ƒ ƒ ƒ ƒ ƒ

Concentric Conical Eccentric Integral Quadrant Segmental

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221

Orifice Plate Taps ƒ ƒ ƒ ƒ ƒ

Corner Flange Full flow Radius Vena Contracta

Upstream Downstream 0D 0D 1 inch 1 inch 2.5D 8D 1D 0.5D 1D vena contracta

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Venturi Primary Flow Element Throat Flow

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Flow Nozzle Primary Flow Element Nozzle Flow

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224

V-Conetm Primary Flow Element V-Conetm Flow

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225

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Differential Pressure Multi-Valve Manifold Designs ƒ Multi-valve manifolds are used to isolate the transmitter from service for maintenance and calibration ƒ One-piece integral assembly ƒ Mounted on transmitter

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226

Differential Pressure Multi-Valve Manifold Designs Three Valve Manifold Low

Downstream Tap

High

Upstream Tap

Transmitter Impulse Tubing (typical)

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227

Differential Pressure Multi-Valve Manifold Designs Drain/Vent

Five Valve Manifold

Low

Downstream Tap

High

Upstream Tap

Transmitter Impulse Tubing (typical) Calibration

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Differential Pressure Multi-Valve Manifold Designs ƒ Removal from service ƒ ƒ ƒ ƒ

Open bypass valve (hydraulic jumper) Close block valves Be sure to close bypass valve to calibrate Use calibration and vent/drain valves (five valve manifold)

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229

Differential Pressure Multi-Valve Manifold Designs ƒ Return to service ƒ Open bypass valve (hydraulic jumper) ƒ Open block valves ƒ Close bypass valve

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230

Differential Pressure Multi-Valve Manifold Designs ƒ Removal and return to service procedure may be different when flow of fluid in tubing/transmitter is dangerous ƒ High pressure superheated steam

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Impulse Tubing No! (gas)

Orifice Plate

Liquid

L H

No! (dirt)

Transmitters

Liquid Flow

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232

Impulse Tubing Transmitters

H L

Orifice Plate

Gas

No! (dirt, condensate) Gas Flow

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233

Impulse Tubing Condensate legs (typical) Orifice Plate

Steam L H

No! (dirt, condensate)

Transmitters Steam Flow

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Impulse Tubing Same Elevation (shown offset)

Orifice Plate

Condensate legs (same height) L H

Steam Flow

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235

Impulse Tubing ƒ ƒ ƒ ƒ ƒ

Liquids Gas Vapor Hot Cold

avoid collection of gas avoid collection of liquid form condensate legs locate transmitter far from taps insulate and/or heat trace

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236

Flowmeter Technologies ƒ Introduction ƒ Differential Pressure

ƒ Magnetic ƒ ƒ ƒ ƒ

Mass Open Channel Oscillatory Positive Displacement

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

ƒ Target Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ Faraday’s Law of Electromagnetic Induction defines the magnitude of the voltage induced in a conductive medium moving at a right angle through a magnetic field ƒ Most notably applied to electrical power generation

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238

Principle of Operation ƒ Faraday’s Law E = constant • B • L • v ƒ B is the magnetic flux density ƒ L is the path length ƒ v is the velocity of the medium

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239

Principle of Operation ƒ Experiment ƒ Galvanometer with wire between terminals ƒ Horseshoe magnet ƒ Moving the wire through the magnetic field moves the galvanometer indicator ƒ Moving wire in opposite direction moves indicator in opposite direction ƒ Moving wire faster moves indicator higher Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Tube (non-magnetic) Magnet

Liner (insulating)

Flow

Electrode Magnetic Field Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

241

Principle of Operation ƒ Magnetic flowmeters direct electromagnetic energy into the flowing stream ƒ Voltage induced at the electrodes by the conductive flowing stream is used to determine the velocity of fluid passing through the flowmeter Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

242

Principle of Operation ƒ Induced voltage E = constant • B • D • v ƒ Substituting Q = A • v and assuming that A, B, and D are constant yields: E = constant • Q Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ The induced voltage at the electrodes is directly proportional to the flow rate

EαQ

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244

Principle of Operation AC Excitation ƒ Magnet is excited by an AC waveform ƒ Voltage waveform at electrode is also an AC waveform

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245

Principle of Operation AC Excitation ƒ AC excitation was subject to: ƒ Stray voltages in the process liquid ƒ Electrochemical voltage potential between the electrode and process fluid

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Principle of Operation AC Excitation ƒ AC excitation was subject to: ƒ Inductive coupling of the magnets within the flowmeter ƒ Capacitive coupling between signal and power circuits ƒ Capacitive coupling between interconnection wiring

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247

Principle of Operation AC Excitation ƒ Zero adjustments were used to compensate for these influences and the effect of electrode coating ƒ Percent of full scale accuracy

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248

Principle of Operation AC Excitation ƒ Feeding power to the primary element, then back to the transmitter reduces the possibility of inducing voltage from the power wiring ƒ Electromagnet is the large power draw ƒ Signal voltage could be induced from wiring carrying current to the magnet Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation DC Excitation ƒ Pulsed DC excitation reduces drift by turning the magnet on and off Magnet On = Signal + Noise Magnet Off = Noise

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250

Principle of Operation DC Excitation ƒ Noise is canceled by subtracting these two measurements Signal + Noise – Noise = Signal

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251

Principle of Operation DC Excitation ƒ DC magnetic flowmeters automatically self-zero ƒ Percent of rate accuracy ƒ The 4mA analog output zero adjustment is not set automatically and still maintains a percent of full scale accuracy

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Principle of Operation DC Excitation ƒ Response time can be compromised

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253

Magnetic Flowmeter Designs ƒ ƒ ƒ ƒ ƒ

Ceramic Electrodeless Low Flow Medium Flow High Flow

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254

Magnetic Flowmeter Designs ƒ ƒ ƒ ƒ ƒ ƒ

High Noise Low Conductivity Partially-full Response - Fast Sanitary Two-wire Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Magnetic Flowmeter Designs ƒ ƒ ƒ ƒ

External/Internal Coils Flanged Wafer Miniature

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256

Flowmeter Technologies ƒ Introduction ƒ Differential Pressure ƒ Magnetic

ƒ Mass ƒ ƒ ƒ ƒ

Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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257

Principle of Operation ƒ Coriolis mass flowmeters use the properties of mass to measure mass ƒ Thermal mass flowmeters assume constant thermal properties

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Principle of Operation ƒ Coriolis acceleration

Coriolis Force

r

r

ω

Man Standing Still

ω

Δr

Man Moving Outward

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259

Principle of Operation ƒ Man Standing Still ƒ Velocity in tangential plane is constant F tang = m • a tang = m • Δ v tang / Δ t = m • (r • ω – r • ω) / Δ t =m•0/Δt = 0 (no force in tangential plane) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

260

Principle of Operation ƒ Man Moving Outward ƒ Velocity in tangential plane changes F tang = m • a tang = m • Δ v tang / Δ t = m • ((r + Δ r) • ω – r • ω) / Δ t =m•Δr•ω/Δt ≠ 0 (force in tangential plane) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation ƒ Components that produce Coriolis force ƒ Rotation ƒ Motion towards/away from center of rotation ƒ Resultant Coriolis acceleration

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262

Principle of Operation ƒ U-tube Coriolis mass flowmeter ƒ Rotation ƒ Oscillation about a plane parallel to the centerline of the piping connections

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263

Principle of Operation ƒ U-tube Coriolis mass flowmeter ƒ Motion towards/away from center of rotation ƒ Mass flow through U-tube towards/away from the centerline of piping connections

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Principle of Operation ƒ U-tube Coriolis mass flowmeter ƒ Coriolis force ƒ Twist of U-tube

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265

Principle of Operation Motion Toward Centerline of Rotation Centerline of Rotation

Coriolis Forces Twist U-tube Flow

Motion Away from Centerline of Rotation

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266

Principle of Operation Experiment ƒ Hold a garden hose with both hands so it sags near the floor (like a U-tube) ƒ Turning water on/off has little affect on the position of the hose

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Principle of Operation Experiment ƒ Swing the hose toward and away from your body ƒ Turning on the water will cause the sides of the U-tube to move towards/away from you ƒ Stopping the swinging will stop the movement and relax the U-tube Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

268

Principle of Operation ƒ Coriolis acceleration is proportional to the mass flow ƒ Coriolis acceleration generates a force ƒ Coriolis force twists the U-tube

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269

Principle of Operation ƒ Mass flow is proportional to the Coriolis force that twists the U-tube ƒ Measure the twist of the U-tube

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Principle of Operation ƒ Amount of twist depends on mechanical properties of the U-tube ƒ Material ƒ Wall thickness ƒ Temperature

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271

Principle of Operation ƒ Temperature Measurement ƒ Pipe wall temperature is measured to compensate for material properties ƒ Many Coriolis mass flowmeters offer (an optional) temperature measurement output ƒ Not process temperature ƒ Outside pipe wall temperature

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272

Principle of Operation ƒ Density Measurement ƒ The frequency of oscillation is related to fluid density ƒ Many Coriolis mass flowmeters offer (an optional) density measurement output

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Principle of Operation ƒ Viscosity Measurement ƒ In the laminar flow regime, the mass flow measurement, temperature measurement, and external differential pressure measurement across the flowmeter is used to calculate viscosity

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274

Principle of Operation ƒ Viscosity Measurement ƒ To counteract the effects of pipe vibration, one Coriolis mass flowmeter uses a weight that twists the tube ƒ Measurement of the forces due this twist are used to determine the fluid viscosity

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275

Tube Geometry – Single U-tube Drive Coil

Outer Case

Flow

Sensor (attached to case)

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Tube Geometry – Single U-tube ƒ First practical design ƒ Sensors connected to case ƒ Measure movement relative to case ƒ Susceptible to pipe vibration ƒ Rigid support structures ƒ Metal plate ƒ Concrete foundation

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277

Tube Geometry – Dual U-tube Drive Coil

Outer Case Recombined Flow

Flow split between upper and lower tubes (one tube shown) Flow

Sensor Detects Movement Between the Tubes

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278

Tube Geometry – Dual U-tube ƒ Flow split between two tubes ƒ Sensors connected to case ƒ Measure relative movement of tubes ƒ Reduced susceptibility to pipe vibration ƒ Mount flowmeter in piping

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Tube Geometry – B-Tube Two Single Tubes

Flow Inlet

B-tube Design Foxboro

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280

Tube Geometry – Curved Tube Flow Splitters Flow

Dual Tubes

Curved Tube Design Endress+Hauser, Micromotion, Oval

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281

Tube Geometry – Curved Tube Flow Splitters

Flow

Dual Tubes

Curved Tube Design ABB

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Tube Geometry – Delta Flow Splitters Flow

Dual Tubes

Delta Tube Design Micromotion

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283

Tube Geometry – Diamond Flow Splitters Flow

Dual Tubes

Diamond Tube Design Kueppers

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284

Tube Geometry – Omega Flow Splitters Flow

Dual Tubes

Omega Tube Design Actaris (Schlumberger)

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Tube Geometry – Omega Flow Splitters Flow

Dual Tubes

Omega Tube Design Heinrichs

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286

Tube Geometry – Round Flow

Flow Splitters

Dual Tubes

Round Tube Design Rheonik

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287

Tube Geometry – Straight Flow Splitters Flow

Dual Tubes

Straight Dual Tube Design Endress+Hauser

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96

Tube Geometry – Straight

Flow

Single Tube

Straight Single Tube Design Brooks, Endress+Hauser, Krohne, Micromotion, Oval

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289

Tube Geometry – S-Tube Flow Splitter

Flow Splitter Flow

Dual Tubes

S-Tube Design FMC Energy Systems

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290

Tube Geometry – S-Tube Flow Splitter

Flow Splitter Flow

Dual Tubes

S-Tube Design FMC Energy Systems

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291

97

Tube Geometry – S-Tube Flow Splitter

Flow Splitter Flow

Dual Tubes

S-Tube Design Krohne

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292

Tube Geometry– U-Tube

Flow

Single Tube

Single U-Tube Design Brooks, Micromotion

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293

Tube Geometry– U-Tube Flow Splitter

Flow Splitter

Flow

Dual Tubes

Dual U-Tube Design Micromotion, Oval, Yokogawa

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294

98

Tube Geometry – U-Tube

Flow

Single Tube

U-Tube Design Danfoss

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295

Fluid Characteristics ƒ Single-phase homogeneous ƒ Liquid ƒ Gas ƒ Vapor

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296

Fluid Characteristics ƒ Two-phase ƒ Liquid/solid ƒ Liquid/gas

ƒ Avoid flashing

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297

99

Fluid Characteristics ƒ Within accurate flow range ƒ Corrosion and erosion ƒ Immiscible fluids

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298

Piping and Hydraulics ƒ For liquid applications, keep the flowmeter full of liquid ƒ Hydraulic design ƒ Vertical riser preferred ƒ Avoid inverted U-tube

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299

Piping and Hydraulics ƒ For liquid applications, orient to self-fill and self-drain ƒ Self-filling is important to ensure a full pipe ƒ If not, special precautions must be taken when zeroing the flowmeter ƒ If not, gas/vapor can accumulate, especially at low flow conditions

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300

100

Piping and Hydraulics ƒ For liquid applications, keep the flowmeter full of liquid ƒ Hydraulic design ƒ Be careful when flowing downwards ƒ Be careful when flowing by gravity

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301

Piping and Hydraulics ƒ For gas/vapor applications, keep the flowmeter full of gas/vapor ƒ Hydraulic design ƒ Self-draining ƒ Vertical preferred ƒ Avoid U-tube

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302

Piping and Hydraulics ƒ For gas/vapor applications, calculate pressure drop carefully ƒ Mass flow range of a given size flowmeter is fixed ƒ Relatively small mass occupies a relatively large volume ƒ High velocity and high pressure drop result ƒ Flowmeter will operate low in its range Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

303

101

Performance ƒ Premium ƒ Typical: 0.1% rate plus zero stability

ƒ Low cost ƒ Typical: larger of 0.5% rate or zero stability

ƒ Analog output ƒ Typical: up to 0.1% of full scale ƒ Sometimes not available Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

304

Flowmeter Technologies ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass

ƒ Open Channel ƒ Oscillatory ƒ Positive Displacement ƒ Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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305

Open Channel - Flume Primary Flow Element Level Measurement

Throat

Flow

Converging Section

Diverging Section

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306

102

Open Channel - Weir Primary Flow Element

Rectangular

Cipolletti

Level Measurement

Triangular

Weir

Flow

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307

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel

ƒ Oscillatory ƒ Positive Displacement ƒ Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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308

Principle of Operation ƒ Fluidic flowmeters are flowmeters that generate oscillations as a result of flow ƒ The number of oscillations can be related to the flow rate

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309

103

Principle of Operation ƒ Examples of fluidic phenomena ƒ Wind whistling through branches of trees ƒ Swirls downstream of a rock in a flowing stream ƒ Flag waving in breeze

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310

Principle of Operation ƒ Fluidic flowmeters ƒ Fluidic flowmeter (Coanda effect) ƒ Vortex precession flowmeter (swirl) ƒ Vortex shedding flowmeter

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311

Coanda Effect Fluidic Flowmeter ƒ Coanda Effect ƒ Flow tends to attach itself to flat surface

ƒ Fluidic oscillator ƒ Passages allow portion of flow to feed back and impinge on incoming stream ƒ Alternating attachment

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312

104

Coanda Effect Fluidic Flowmeter ƒ Frequency of alternating attachments is proportional to flow ƒ Doubling the flow doubles the number of attachments

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313

Coanda Effect Fluidic Flowmeter ƒ Reynolds number constraints ƒ Over 500

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314

Coanda Effect Fluidic Flowmeter Feedback Passage

Sensor

Flow

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315

105

Coanda Effect Fluidic Flowmeter ƒ Sensors ƒ Deflection ƒ Thermal

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316

Vortex Precession Flowmeter ƒ Often called a “swirlmeter” ƒ Inlet vanes cause the flow to spin and form a cyclone ƒ The tip of the cyclone moves around the inside pipe wall (precession) ƒ Outlet vanes remove swirl from the flow

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317

Vortex Precession Flowmeter ƒ Speed that vortex rotates around the pipe is proportional to flow ƒ Doubling the flow doubles the precession

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318

106

Vortex Precession Flowmeter Sensor

Flow

Inlet Guide Vanes

Outlet Guides

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319

Vortex Precession Flowmeter ƒ Sensors ƒ Piezoelectric

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320

Vortex Shedding Flowmeter ƒ An obstruction (bluff body or strut) is located in the flow stream ƒ Low flow - fluid flows around obstruction ƒ High flow - alternating vortices are formed ƒ Number of vortices formed is proportional to fluid velocity

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321

107

Vortex Shedding Flowmeter ƒ The sensing system detects the vortices created ƒ The frequency of the vortices passing the sensing system is proportional to fluid velocity

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322

Vortex Shedding Flowmeter Sensor Vortex

L

Flow L

L

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323

Vortex Shedding Flowmeter ƒ Bluff body is typically approximately 20% of the pipe ID ƒ Pressure drop across similar vortex shedders in the same service is similar ƒ For liquids: 5 psid at 15 ft/sec 400 mbar at 5 m/s

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324

108

Vortex Shedding Flowmeter Problem ƒ What is the approximate pressure drop across a vortex shedder at 7.5 ft/sec?

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325

Vortex Shedding Flowmeter ƒ (5 • 7.5/15) = 2.5 psig might be tempting, but in the turbulent flow regime, the pressure drop across a restriction varies as the square of the flow ƒ Double the flow, four times the differential ƒ The pressure drop will be 5 • (7.5/15)2 = 1.25 psig approximately Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

326

Vortex Shedding Flowmeter ƒ Strut design is like a “piano wire” ƒ Gas flow measurement ƒ Low pressure drop

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327

109

Vortex Shedding Flowmeter Strut

Ultrasonic Sensor

Vortex

L

Flow L

L

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328

Vortex Shedding Flowmeter Sensing Systems ƒ Shedder and sensing system tradeoffs are made in the design process to: ƒ operate linearly ƒ operate at low velocity ƒ operate at low Reynolds numbers

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329

Vortex Shedding Flowmeter Sensing Systems ƒ Shedder and sensing system tradeoffs are made in the design process to: ƒ reduce the effect of short straight run ƒ reduce the effects of misalignment ƒ reduce the effects of vibration

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330

110

Vortex Shedding Flowmeter Sensing Systems ƒ Shedder and sensing system tradeoffs are made in the design process to: ƒ reduce the possibility of leaks ƒ All-welded body designs

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331

Vortex Shedding Flowmeter Sensing Systems ƒ Hydraulic energy to operate the sensing system is usually provided by the fluid ƒ Flowmeter turns off at low velocity

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332

Vortex Shedding Flowmeter Sensing Systems ƒ Velocity constraint is a function of density ƒ Lower density increases low velocity limit ƒ Higher density decreases low velocity limit

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111

Vortex Shedding Flowmeter Sensing Systems ƒ Typical Velocity Constraints ƒ Water ƒ Free air ƒ Air (8 bar)

0.35 m/s 6.5 m/s 3.5 m/s

1 ft/sec 21 ft/sec 11.5 ft/sec

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334

Vortex Shedding Flowmeter Sensing Systems ƒ Reynolds Number Constraint ƒ Sufficient Reynolds number is needed to generate oscillations ƒ Flowmeter turns off at low Reynolds numbers

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335

Vortex Shedding Flowmeter Sensing Systems ƒ Reynolds number constraints ƒ ƒ ƒ ƒ

Linear operation Turn off Nonlinear Small sizes

over 10-30,000 3-10,000 between turn off / linear

ƒ Lower Reynolds number limits

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336

112

Vortex Shedding Flowmeter Sensing Systems ƒ Both Reynolds number and velocity constraints must be satisfied for vortex shedding flowmeters to operate

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337

Vortex Shedding Flowmeter Sensing Systems Problem ƒ Will a vortex shedding flowmeter measure the flow of a liquid operating at a Reynolds number of 1,000,000 at a velocity of 0.1 m/s? ƒ No --- the velocity is below the minimum velocity constraint Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

338

Vortex Shedding Flowmeter Sensing Systems Problem ƒ Will a vortex shedding flowmeter measure the flow of a liquid operating at a Reynolds number of 100 at a velocity of 10 m/s? ƒ No --- the velocity is below the minimum Reynolds number constraint Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

339

113

Vortex Shedding Sensor Deflection Sensor Vortex

L

Flow L

L

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340

Vortex Shedding Sensor Deflection Sensor Vortex

L

Flow L

L

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341

Vortex Shedding Sensor Differential Pressure Sensor Vortex

L

Flow L

L

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342

114

Vortex Shedding Sensor Differential Pressure Sensor Vortex

L

Flow L

L

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343

Vortex Shedding Sensor Shedder Twist Sensor Vortex

L

Flow L

L

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344

Vortex Shedding Sensor Thermal Thermal Sensor Vortex

L

Flow L

L

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345

115

Vortex Shedding Sensor Torque Tube Torque Tube Vortex

L

Flow L

L

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346

Vortex Shedding Sensor Ultrasonic Ultrasonic Sensor

Vortex

L

Flow L

L

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347

Vortex Shedding Flowmeter Sensing Systems ƒ Vibration effects ƒ Acceleration compensation ƒ ƒ ƒ ƒ

Fishtail design with embedded sensor Fishtail design with counterbalancing Torque tube design Shedder twist design

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348

116

Vortex Shedding Sensor Fishtail Design Embedded Sensor Vortex

L

Flow L

L

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349

Vortex Shedding Sensor Fishtail Design External Sensor Vortex

L

Flow L

L

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350

Vortex Shedding Sensor Torque Tube Torque Tube Vortex

L

Flow L

L

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351

117

Vortex Shedding Sensor Shedder Twist Center of Rotation (offset for clarity)

Vortex

L

Flow L

L

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352

Vortex Shedding Flowmeter Sensing Systems ƒ Early designs were not balanced ƒ Subsequent designs were balanced ƒ No mass designs (such as thermal and ultrasonic) do not have to be acceleration compensated

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353

Vortex Shedding Sensor Multivariable ƒ Embedded temperature sensors ƒ Embedded flow computer ƒ Pressure and temperature compensation ƒ Reynolds number compensation

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354

118

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory

ƒ Positive Displacement

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

ƒ Target Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

355

Positive Displacement Flowmeter ƒ Positive displacement flowmeters measure flow by repeatedly entrapping fluid within the flowmeter ƒ Moving parts with tight tolerances ƒ Bearings ƒ Many shapes

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356

Positive Displacement Flowmeters

Nutating Disk

Oval Gear Oscillating Piston

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357

119

Positive Displacement Flowmeter ƒ Sensing systems ƒ ƒ ƒ ƒ

Mechanical Magnetic Radio frequency Optical

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358

Positive Displacement Flowmeter ƒ Maintenance ƒ ƒ ƒ ƒ

Plugging Bearing wear Abrasion Leaks

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359

Positive Displacement Flowmeter 10

%Rate 1 Error -1

>1000 cP

0.1

10

1

100

Flow

3 cP -10

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120

Positive Displacement Flowmeter 30,000 cP 100 Pressure Drop as Percent of Maximum Rating

3 cP

0 0.1

1

10

100

Flow

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Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

ƒ Target Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

362

Target Flowmeter ƒ Target flowmeters determine flow by measuring the force exerted on a body (target) suspended in the flow stream

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363

121

Target Flowmeter

Flow

Target

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364

Target Flowmeter ƒ Dynamic balance with flowing stream ƒ Same equations as differential pressure flowmeters ƒ Affected by density (+1% specific gravity change affects flowmeter by -0.5%)

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365

Target Flowmeter ƒ Maintenance ƒ ƒ ƒ ƒ

Target wear Coating Leaks Drift

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366

122

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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367

Thermal Flowmeter ƒ Thermal flowmeters use the thermal properties of the fluid to measure flow ƒ Hot Wire Anemometer ƒ Thermal Profile

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368

Thermal Flowmeter Hot Wire Anemometer ƒ Hot wire anemometers determine flow by measuring the amount of energy needed to heat a probe whose heat loss changes with flow rate

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123

Thermal Flowmeter Hot Wire Anemometer

Flow

Thermal Sensor

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370

Thermal Flowmeter Thermal Profile ƒ Thermal profile flowmeters determine flow by measuring the temperature difference that results in a heated tube when the fluid transfers heat from the upstream portion to the downstream portion of the flowmeter

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371

Thermal Flowmeter Thermal Profile Temperature Sensors Heater

Heater Flow

Zero Flow

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372

124

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal

Turbine Ultrasonic Variable Area Correlation Insertion Bypass

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373

Turbine Flowmeter ƒ Fluid flow causes a rotor to spin whereby the rotor speed is proportional to fluid velocity ƒ Primary Flow Element ƒ Transmitter

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374

Turbine Flowmeter Sensor/Transmitter

Rotor Flow

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125

Turbine Flowmeter ƒ The sensor detects the rotor blades ƒ The frequency of the rotor blades passing the sensor is proportional to fluid velocity

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376

Turbine Flowmeter ƒ Operating constraints ƒ Turbulent flow regime ƒ 10-600mm (0.5 to 24 inch) ƒ Application-specific designs have limited temperature capability (natural gas) ƒ Minimum/maximum velocity ƒ Lubricity (often difficult to quantify) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

377

Turbine Flowmeter ƒ Maintenance ƒ Bearing wear ƒ Rotor damage ƒ Sensor failure

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126

Turbine Flowmeter ƒ Designs ƒ ƒ ƒ ƒ

Axial Paddle wheel Propeller Tangential

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379

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine

Ultrasonic Variable Area Correlation Insertion Bypass

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380

Principle of Operation ƒ Ultrasonic flowmeters direct ultrasonic energy into the flowing stream ƒ Information from the remnants of this energy is used to determine the velocity of fluid passing through the flowmeter

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127

Principle of Operation ƒ Sensing the remnants is predicated upon a complete ultrasonic circuit ƒ ƒ ƒ ƒ ƒ

Transmitting device Entry pipe wall (and liner) Fluid (and reflections off pipe wall) Exit pipe wall (and liner) Receiving device Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

382

Principle of Operation ƒ To function properly, all parts of the ultrasonic circuit must allow sufficient energy to pass

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383

Principle of Operation ƒ Weak signals may cause the flowmeter to be erratic or cease to function ƒ ƒ ƒ ƒ ƒ

Paint Dry ultrasonic coupling compound Pipe wall coating or corrosion Poorly bonded liner Tuberculation (barnacles) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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128

Principle of Operation ƒ Ultrasonic noise may cause the flowmeter to be erratic or cease to function ƒ Nearby radio transmitter ƒ Control valve with “quiet” trim

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Principle of Operation Doppler Ultrasonic ƒ Doppler ultrasonic flowmeters reflect ultrasonic energy from particles, bubbles and/or eddies flowing in the fluid

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386

Principle of Operation Doppler Ultrasonic Transmitter

Flow

Receiver

Reflection Bubbles or Solids

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129

Principle of Operation Doppler Ultrasonic ƒ Under no flow conditions, the frequencies of the ultrasonic beam and its reflection are the same ƒ With flow in the pipe, the difference between the frequency of the beam and its reflection increases proportional to fluid velocity Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Doppler Ultrasonic ƒ Doppler Equation vf = K • Δf ƒ K = constant ƒ vf = velocity of fluid where ultrasonic energy is reflected ƒ Δf = difference between the transmitted and reflected frequencies Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Transit Time Ultrasonic ƒ Transit time (time-of-flight) ultrasonic flowmeters alternately transmit ultrasonic energy into the fluid in the direction and against the direction of flow

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Principle of Operation Transit Time Ultrasonic Sensor

Flow

Sensor

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Principle of Operation Transit Time Ultrasonic ƒ The time difference between ultrasonic energy moving upstream and downstream in the fluid is used to determine fluid velocity

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392

Principle of Operation Transit Time Ultrasonic ƒ Under no flow conditions, the time for the ultrasonic energy to travel upstream and downstream are the same Sensor

Flow

Sensor Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Transit Time Ultrasonic ƒ With flow in the pipe, the time for the ultrasonic energy to travel upstream will be greater than the downstream time Sensor

Flow

Sensor Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Transit Time Ultrasonic ƒ Transit Time Equation vp = K • (Tu – Td) Tu • Td ƒ ƒ ƒ ƒ

vp = average fluid velocity in the path K = constant Tu = upstream transit time in fluid Td = downstream transit time in fluid Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Transit Time Ultrasonic ƒ Tu and Td are dependent upon the speed of sound in the fluid ƒ Some designs use measurements and equations that are not dependent upon the speed of sound in the fluid

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Principle of Operation Pulse Repetition Ultrasonic ƒ Pulse repetition (sing-around) ultrasonic flowmeters alternately transmit ultrasonic energy into the fluid in the direction and against the direction of flow ƒ The receipt of one ultrasonic pulse triggers the sending of a new ultrasonic pulse Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Principle of Operation Pulse Repetition Ultrasonic ƒ The frequency that the pulses are repeated is used to determine fluid velocity

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Principle of Operation Pulse Repetition Ultrasonic ƒ Pulse Repetition Equation vp = K • (fu – fd) ƒ ƒ ƒ ƒ

vp = average fluid velocity in the path K = constant fu = frequency of upstream transit time period fd = frequency of downstream transit time period Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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133

Single Path Geometry Sensor

Flow

Sensor

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400

Single Path Geometry Sensor

Flow

Sensor

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401

Single Path Geometry Sensor

Flow

Sensor One Reflection

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Single Path Geometry Sensor

Two Reflections

Flow

Sensor

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403

Single Path Geometry Sensor

Sensor

Flow

Three Reflections

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404

Single Path Geometry In

Out

Sensor Sensor

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Multiple Path Geometry Sensor

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406

Chordal Path Geometry Sensor

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407

Ultrasonic Flowmeters ƒ Applications (general) ƒ ƒ ƒ ƒ

Large pipes Flashing fluids Corrosive fluids Hazardous fluids

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Ultrasonic Flowmeters ƒ Applications (specific) ƒ Custody transfer ƒ Natural gas ƒ Petroleum products

ƒ Stack gas ƒ Flare gas

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Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic

Variable Area Correlation Insertion Bypass

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Principle of Operation Metering Float

Metering Tube

Flow

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Principle of Operation Weight of float minus weight of fluid it displaces

Dynamic Balance

Pressure due to fluid velocity Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area

Correlation Insertion Bypass

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Correlation Flowmeters Principle of Operation ƒ Correlation flowmeters determine fluid velocity by measuring parameters associated with the flowing stream at different places in the piping

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Correlation Flowmeters Ultrasonic Sensor

Flow

Distance

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415

Correlation Flowmeters Pressure Sensor Array

Flow

Sensor Array (wraps around pipe) Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

416

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation

Insertion Bypass

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Insertion Flowmeter ƒ Insertion flowmeter infer the flow in the entire pipe by measuring flow at one or more strategic locations in the pipe

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418

Insertion Flowmeter Theoretical Velocity Profile Average velocity

Rd = 4,000,000

Flow

Rd = 4000

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Insertion Flowmeter Sensor Flow

Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Insertion Flowmeter ƒ Technologies ƒ ƒ ƒ ƒ ƒ ƒ

Differential Pressure Magnetic Target Thermal Turbine Vortex Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

421

Flowmeter Technologies ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Differential Pressure Magnetic Mass Open Channel Oscillatory Positive Displacement Target

Thermal Turbine Ultrasonic Variable Area Correlation Insertion

Bypass

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422

Principle of Operation ƒ Divide the flowing fluid into a large and small flowing stream ƒ It is important to ensure a known ratio between these flows

ƒ Measure the flow of the small stream to infer the total flow of the fluid

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141

Bypass Flowmeter Orifice Plate Bypass Flowmeter

Flow

Orifice Plate

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Seminar Outline ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies

ƒ Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Factors in Flowmeter Selection ƒ Flowmeter classes ƒ ƒ ƒ ƒ

Wetted moving parts No wetted moving parts Obstructionless Non-wetted (external)

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Factors in Flowmeter Selection ƒ Flowmeter measurements ƒ ƒ ƒ ƒ

Volume Velocity Mass Inferential

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427

Factors in Flowmeter Selection ƒ Performance ƒ Accuracy

ƒ End use ƒ ƒ ƒ ƒ

Indication Control Totalization Alarm Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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Factors in Flowmeter Selection ƒ ƒ ƒ ƒ ƒ

Power requirements Safety Rangeability Materials of construction Maintainability

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Factors in Flowmeter Selection ƒ ƒ ƒ ƒ ƒ

Ease of application Ease of installation Installed cost Operating cost Maintenance cost

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430

Data for Flowmeter Selection ƒ Performance ƒ Fluid properties ƒ ƒ ƒ ƒ

Fluid name Fluid state(s) Compatibility of materials Pressure and temperature

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431

Data for Flowmeter Selection ƒ Fluid properties ƒ ƒ ƒ ƒ

Specific gravity and density Fluid viscosity Operating range Other (conductivity, thermal capacity, vapor pressure…)

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Data for Flowmeter Selection ƒ Installation ƒ ƒ ƒ ƒ ƒ ƒ

Pipe size Differential pressure Pipe vibration Pulsating flow Straight run Ambient conditions Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

433

Data for Flowmeter Selection ƒ Operation ƒ ƒ ƒ ƒ

Maintenance Availability of parts and service Installed cost Operating cost

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434

Data for Flowmeter Selection ƒ Future considerations ƒ Plant expansion

ƒ Risk

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Flowmeter Selection ƒ Typical selection process ƒ Trial and error until one “works” ƒ Potential lost opportunity

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436

Flowmeter Selection ƒ Proposed selection process ƒ Disqualify inappropriate technologies using technical and non-technical criteria ƒ Select the best flowmeter from the remaining technologies

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437

Flowmeter Selection ƒ Technical criteria ƒ Items or issues that absolutely disqualify a technology

ƒ Non-technical criteria ƒ Preferences

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Review and Questions ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ

Introduction Fluid Flow Fundamentals Performance Measures Linearization and Compensation Totalization Flowmeter Calibration Measurement of Flowmeter Performance Miscellaneous Considerations Flowmeter Technologies Flowmeter Selection Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

439

Industrial Flow Measurement Seminar Presented by David W. Spitzer Spitzer and Boyes, LLC Copyright Copperhill and Pointer, Inc., 2004 (All Rights Reserved) www.spitzerandboyes.com +1.845.623.1830

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