Assignment Lab Session No.1.docx

“In the name of Allah, the most Beneficent and the most Merciful”

Assignment Lab Session No.1

November 5

2015

Submitted To: Sir Harris Husain Submitted By: M.Rehman Saghir Regd.No: 2015-ME-25 Section: A(Mechanical)

Pressure Gauge “Pressure Gauges measure the increase and reduction of pressure in a contained field.”(1)

Types of Pressure Gauges: There are many types of gauges depending upon their uses. Their names are:

1).Air Pressure Gauges: 2).Oil Pressure Gauges: 3).Differential Pressure Gauges: 4).Digital Pressure Gauges: 5).Diaphragm Pressure Gauges: Here we will explain these.

1).Air Pressure Gauges: These types of gauges are used to determine the pressure of a gas in an object to maintain it at a proper level s that the object may work properly. Commonly the objects in which the pressure of a gas is measured by these types of gauges are the tires of vehicles. And that specific gas is pressurized air in tires. This measurement is very important for the proper working of vehicles. For example if the pressure is low in the tire then it will cause the vehicle to slowdown. And if the pressure is very high then the tire may be explode. These can also check the extra air, which reduces the resistance for rolling and it also makes the tire stiff.Fig-1,2

1

Figure 1

Figure 2

2).Oil Pressure Gauges:

Figure 3

Figure 4

These types of Gauges can measure the oil pressure and usually it is fixed on the dashboard of car. There are different mobile parts of machine engines which require a proper lubrication by lubricating oils to prevent the natural friction in the motion so that the components may not

2

damage. So these gauges indicate the safe or unsafe level in time so that we may save from a serious and expensive loss of any part of engine.Fig-3,4

3).Differential Pressure Gauges: These types of gauges can show a variation in pressure between two points. As it works between two points so it has necessarily two ports for the fluids t entre. It is easy to check pressure at one point rather than using two pressure gauges and determining the pressure by them and taking the difference. This is for both gases and liquids. Aircraft gauges is the example

of differential pressure gauges.Fig-5 Figure 5

4).Digital Pressure Gauges:

3

Figure 6

Digital pressure gauges show the applied pressure into the digital and numeric values by converting it to the electrical signals. As it is easy to use and free from personal errors so they have a wide range of applications in automotive and many other industries like pharmaceutical and food processing. It has also use for checking and monitoring of hazardous materials.Fig-6

5).Diaphragm Pressure Gauges: In this pressure gauge an expandable membrane or diaphragm is used whose deformation extent gives the pressure. There are two sides of diaphragm. Diaphragm is used to divide a capsule contained in the gauge. This capsule is open to connect it with an unknown pressure and the other side is connected to the known pressure. The magnitude of the deformation of

4

membrane is directly proportional to the pressure to be measured.Fig-7

Figure 7

Calibration Methods Of Pressure Gauges There are the following methods to calibrate a pressure gauges:

1).Calibration using Deadweight tester: This apparatus is used for pressure measurements. It contains a lubricating oil used to transmit pressure applied on it by a piston and weight. It has a connecting place where a gauge is connected to be calibrated.

Procedure for Calibration:

5

Figure 8

Step 1: Connect the gauge with apparatus by connecting place and determine that whether the connected gauge is giving zero reading or not. If not then apply zero error. Step 2: Put a known weight on the piston. Step 3: Spin the plunger to ensure that the weight is completely supported by lubricating oil. Step 4: Do not be haste and wait for a few seconds to stabilize the system itself. After stabilization take the reading shown on scale of gauge. Step 5: Now repeat the same experiment by increasing weights on piston until the limit of gauge not crosses. Final work: If we are doing a 11 point calibration then the scale should be calibrated as 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100% of the full range for increasing weights.

6

2).Calibration of adjustable dial gauge: This method is only for the pressure gauges which have an adjustable dial pointer. This method is also called cross check method. In this method, first we take readings by our gauge to be calibrated by applying pressure. Then we take the readings of the same pressure by a standard pressure gauge known to be very accurate. Then the readings of gauge is compared with the readings of standard gauge. Then the gauge is calibrated by readjusting the dial of gauge. Then the experiment is again performed to check whether it is calibrated according to standard or not. In this way the gauge is calibrated.

Industrial Applications of Pressure Gauges (2) Pressure gauges have a large No. of industrial applications. Some of them we will discuss here. 1)

Automotive:

In the automotive industries, there are many processes in which pressure factor is involved and should be controlled by pressure gauges. 2)

Steam Engines:

Steam engines work with boiler in which the pressure of steam is controlled by them. 3)

Oil and gas production industries:

In these industries the pressure of oil extracted from the ground is maintained at particular level and then purify it at high pressure. So to control this high pressure we need pressure gauges. 4)

Natural Gas transmission and distributive industries:

In this industry the suction of gas, discharge and recycle pressures on compressors are the pressure processes involved in it. So to control anyone of these we need the pressure gauges. 5)

Steel Manufacturing industries: 7

There is a large NO. of hydraulic operations are involved in the processing of steel. So to control the pressure of hydraulic press, these are used. 6)

Paper and pulp industries:

In the paper and pulp industries have often their own power plants to increase their product. In these plants, steam is used whose pressure is controlled by them. Also there are many pressing processes in these, so these are very important for them. 7)

Water and Waste water treatment industries:

Water treatment plants pump a large volumes of water. Addition of treatment chemicals can create gauge problems. The pressure of water in pipe line is properly observed by the pressure gauges to pump water consistently. 8)

Tire and Rubber industries:

Tire building and rubber manufacturing industries have a large No. of it’s uses. In these, some processes like plant air system, hydraulic presses are controlled by gauges. 9)

Vehicle manufacturing industries:

In these industries the processes like motor testing, paint and coating systems and press tonnage , the pressure factor should be controlled properly for proper working and that is done by pressure gauges.

References: 1) www.ehow.com/about_5769419_different-types-of-pressure-gauges.html 2) Industrial pressure level and density measurement, 2nd edition By Donald R.Gillum Fig-8= http://2.bp.blogspot.com/-UgR9Kojuk1g/UfzYtSUT9I/AAAAAAAAAp0/tYk4SXSngKw/s1600/How+to+Calibrate+a+Pressure+Gauge+with+a+Dead+W eight+Tester.png

8

9