Elective 2 Pipings.pdf

PIPING, TUBING, FITTINGS, AND CONTROLS

Piping, Tubing, and Fittings

Piping, Tubing, and Fittings   



efficiently fulfill its purpose, easily maintained, and interfere as little as possible with the interior architectural form water supply piping is subject to corrosion over time when pipe materials corrode, they first lose some carrying capacity and ultimately fail

 sediments from corrosion can adversely affect plumbing fixtures as well  for nonferrous piping materials, the following are effective in corrosion resistance

 red brass  copper tubing  For aggressive waters, plastic is often a good choice

Connections  ferrous

pipes and “iron pipe size” brass – threaded connections  copper tubes – solder–joint connection  large ferrous pipes –welded or connected by bolted flanges

Plastic Pipe  most

of the plastic pipes and fittings now produced are synthetic resin

 most

of the materials used for piping are thermoplastics

Water Supply Piping Materials

Water Service Only Material

Connections

ABS (Acrylonitrile butadiene styrene) plastic pipe

Mechanical with elastomeric seal (normally underground only); solvent cement; threaded joints

Asbestos – cement

Sleeve couplings of same material as pipe, sealed with elastomeric ring

Ductile iron water pipe

Depth of lead depends upon pipe size

PE (polyethylene) plastic pipe and tubing

Flared joints (see manufacturer), heatfusion, mechanical joints (see manufacturer)

PE–AL–PE (Polyethylene/aluminium/poly ethylene) pipe PVC (Polyvinyl chloride) plastic pipe

Mechanical with elastomeric seal (normally underground only); solvent cement; threaded joints (may reduce pressure rating)

Water Service and Distribution Material

Connections

Brass pipe CPVC (Chlorinated polyvinyl chloride) plastic pipe (and tubing, indoors)

Copper copper-alloy pipe and tubing Galvanized iron pipe

d

PB (Polybutylene) plastic pipe and tubing PEX (Cross-linked polyethylene) plastic tubing PEX-AL-PEX (Cross-linked polyethylene/cross-linked aluminium/polyethylene) pipe

Brazed, mechanical, threaded, or welded joints Mechanical (see manufacturer), solvent cement, threaded joints (may reduce pressure rating) Brazed, mechanical, soldered, threaded, or welded joints Threaded, or elastomeric seal

mechanical

joints

with

Flared joints, heat-fusion, or mechanical joints (see manufacturer)

Valves and Controls  it

is desirable to valve every  riser  branches

serving bathrooms or kitchens

 runouts

to individual fixtures

 water treatment equipment will have a bypass valved  pumps and other devices that may need repairs should be disconnected by unions after valves are closed

Gate Valve

Globe Valve

Angle Valve

Check Valve

Ball Valve

Pipe Support  water

piping systems are heavy due to their water content

 vertical

runs of piping should be supported at every story

 horizontal

pipes should be supported at intervals of: 6

ft (1.829 m) for ½-in. (12-mm) pipe

8

ft (2.438 m) for ¾-in. or 1-in. (19- or 25-mm) pipe

10

ft (3.048 m) for 1¼-in. (32-mm) or larger pipe

 horizontal

copper tubing should be supported at closer spacing than steel

 adequate

positioning of horizontal runs is important to ensure correct pitch and drainage



hangers purpose

are

adjustable

for

this

SIZING OF WATER PIPES  there

must be sufficient pressure at fixtures to assure the user of a prompt and adequate flow of water  minimum fixture pressures vary from 5 to 20 psi for fixtures other than hose bibbs

 excessive

too

friction results from

long piping

too

many fittings (such as elbows and tees)

too

small in diameter

 developed

length – the actual

distance of water flow

Minimum fixture flow pressure

A

Pressure lost because of height

+B

Pressure lost by friction in piping

+C

Pressure lost by flow through meter + D

Total required street main pressure = E

minimum fixture flow pressure

A

 use

the highest, most remote fixture from the main  the value of A is usually taken from table Table 21.14 Flow and Pressure to Typical Plumbing Fixtures,

Mechanical and Electrical Equipment for Buildings, 11th ed., Stein and Reynolds

pressure lost because of height, B this usually refers to the static height at which water will be delivered

pressure lost by flow through meter, D dependent on the size of meter and the flow

street main pressure, E 

characteristic of the local water supply and is obtained from the water utility

Figure 21.63 Pressure losses in disktype water meters. (a) I-P units. (b) SI units. Mechanical and Electrical

Equipment for Buildings, 11th ed., Stein and Reynolds

to select a pipe size  probable

flow (gpm/Lps)

 unit-friction

loss in the pipe and fittings (psi/100 ft)(Pa/m)

 noise

created by water flow

above

noisy

above

10 fps (3.1 m/s) is usually too

6 fps (1.8 m/s) may be too noisy for acoustical-critical locations

to establish the desired friction loss

the value of C (pressure lost by friction in piping) by the total equivalent length (TEL) of the piping

 divide

 TEL

= developed length + length equivalent to the fittings

DOMESTIC WATER SYSTEM LOAD  The amount of water required is referred to as

water load

 provide the consumers with enough hot and cold water  water demand for plumbing facilities depends on the number and type of fixtures actually installed  Each plumbing fixture is assigned a water supply fixture unit (wsfu) rating

 The water supply fixture unit rating represents the relative water demand for its intended operating functions

step-by-step approach 1.

List the plumbing fixtures required on the project.

2.

The demand for each fixture will be listed.

3.

Calculate the total wsfu of the project.

4.

Determine the total water demand

Table 10.15 Water Supply Fixture Units (Stein and Reynolds . Mechanical and Electrical

Equipment for Buildings, 9th ed., p. 661)

EXAMPLE  Using

the following data, find the proper size for metered water supply main. Street main pressure - 50 psi Height of topmost fixture – 30 ft Fixture type – water closet with flush valve (1.6 gal per flush) Fixture units in the system – 85 wsfu Developed length of the piping – 100 ft Developed length of fittings – 50 ft