Pressure Gauge

16 � MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION

Experiment No. 4 Industrial Measurements

Experiment No.4

1.0 TITLE:To calibrate pressure gauge by using dead weight pressure gauge tester.

2.0 PRIOR CONCEPTS:Pressure, pressure measurement using bourdon tube, construction and working principle of bourdontube.

3.0 NEW CONCEPTS:Proposition 1: Calibration

It is defined as the process of comparison of specific values of input and output of instrument withthe corresponding reference standards.

Concept Structure:

Proposition 2:

Calibration must be performed periodically to test the validity of performance of device or system.

4.0 LEARNING OBJECTIVES:Intellectual Skills

1. To understand the construction and working of bourdon’s tube pressure gauge.

2. To understand the process of calibration.

3. To interpret from the graph and comment on the calibration of the instrument.

Motor skills

1. Ability to note down (measure) the pressure in kg/cm2.

2. Ability to plot graph between o/p pressure of bourdon’s gauge on y axis with input pressureon dead weight gauge on x axis.

MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION � 17

Industrial Measurements Experiment No. 4

5.0 APPARATUS:Bourdon gauge, dead weight tester.

(If the above apparatus is not available, mention the available set up in the laboratory in the followingFormat-)

6.0 DIAGRAM:

Dead weight tester and Bourdon tube pressure gauge



Construction Dead weight tester

7.0 STEPWISE PROCEDURE:Theory: Pressure gauge, especially Bourdon’s gauge is calibrated by means of dead weight tester.The essential components of such a tester is reservoir ‘R’, cylinder ‘C’, barrel ‘B’ and passage up to‘C’ to hold up clean dry oil. A spindle ‘S’ with highly finished surface and precise cross-sectionalarea slides vertically in the barrel ‘B’ through close fitting, highly polished bearing ‘b’ and carries thetable ‘T’ at its upper end. Its lower end rests on ‘HP’ piston.

Screws ‘Ls1’ and ‘Ls

2’ lock the passage of oil when required. The tester is mounted on a stand ‘ST’.

It is provided with special precise weights marked in terms of pressure. A double piston ‘DP’ can bemoved forward and backward by rotating the handle ‘H’. The double acting piston works both waysand does not allow the oil to leak. The gauge under calibration can be connected at ‘D’ such that theconnection is leak tight.

With ‘Ls1’ and ‘Ls

2’ open, the handle is rotated such that the oil is just in level with the gauge

connecting points ‘D’, and ‘Ls2’ is now locked. The gauge ‘G’ is mounted carefully. ‘H’ is rotated until

the table ‘T’ is at raised position in line with the upper edge of colour band. ‘Ls1’ is then locked. ‘Ls

2’

is opened and the handle H is rotated such that the gauge needle just moves and reads someminimum pressure characteristics of the tester because of the weight of the unloaded table actingthrough the piston’ LP’. A weight is placed on the table increasing the pressure on the oil in thetester.

The gauge pressure reading should give a reading corresponding to the amount scribed on theweight if it is operating correctly. If not, the dial is rotated so that the needle points to be correctpressure. Another weight is added and another gauge reading is noted and so on.

A combination of weights can be used with thinner piston ‘HP’, with a multiplying factor given by themanufacturer, Say 20. Such a tester can give pressure values accurate up to + 0.05% of thepressure being measured. The range of pressure is typically 0.5 to 10000 kg / cm2 using dualspindles. The pressure range that dead weight tester can measure is limited by the area of cross –section of the spindle S and the number of weights that can be safely placed on the table.

In order to increase the range, another spindle of smaller cross section can be provided increasingthe pressure range for the same weight placed on the table by a factor equal to the ratio of the crosssectional area of the two spindles.

The weights are typically for 0.05,0.1,0.5,1,2,5,9,10 kg / cm2 .With thinner spindle and factor of 20these can give 1,2,10,20,40,100,130,200 kg / cm2.



1. Assemble Bourdon’s pressure gauge with dead weight tester.

2. Apply pressure in terms of weights on table and measure the value of it on pressure gauge.

3. Repeat the procedure for ascending and descending weights on table and correspondingmeasurement on Bourdon pressure gauge.

4. Plot the graph of applied weights (x-axis) versus pressure on gauge (y-axis)

8.0 OBSERVATIONS:Table of measured pressure on gauge against applied weights.

9.0 CONCLUSION:(Teacher shall guide the students to write conclusion keeping in view the skills acquired and theresult of experiment).

10.0 REFERENCE:1. Refer books given as per curriculum.

2 . Site:www.armfieldco.uk

11.0 QUESTIONS:Write answers to Q…, Q…, Q..., Q…, Q…(Teacher shall allot at least 5 questions to each student)1. What is Calibration? Describe in brief.2. What is Calibration of pressure transducer using dead weight tester?3. Describe Bourdon’s tube as a pressure gauge.4. Define

1. Absolute pressure 2. Atmospheric pressure.5. Give different industrial units of pressure.6. Explain electrical pressure transducers strain gauge.7. With experimental setup, explain how pressure can be measured by using LVDT?8. How piezoelectric transducer can be used for pressure measurement?9. Give principle, construction and working of a U tube Manometer.10. Describe how bellows can be used for pressure measurement.11. Describe how variable capacitor transducer can be used for pressure measurement.12. What is Dead weight pressure gauge?13. Describe the principle, construction and working of any of Elastic pressure transducer.14. Explain how load cell can be used for pressure measurement?15. Describe the Calibration procedure for any of pressure gauge other than Bourdon tube

pressure gauge.



(Space for answers)

Signature of Teacher



GRAPH

Pressure Gauge

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Transcript of Pressure Gauge