Experiment 5 - Calibration Of Bourdon Tube Pressure Gauge (1).doc

FACULT FACULTY Y OF CHEMICAL CHEM ICAL ENGINEERING ENGINEE RING CHE MICAL UNIVERSITI TEKNOLOGI MALAYSIA

FLUID MECHANICS LABORATORY TITLE OF EXPERIMENT

CALIBRATION OF BOURDON TUBE PRESSURE GAUGE   (EXPERIMENT 5) Name Matr! N"# Gr"$% & Se't" S$%er*"r Date "+ E!%ermet Date "+ S$,m**" Mar-* ",tae. (/)

O,0e'te

The objective of this experiment is to perform pressure calibration on a Bourdon tube  pressure gage using a dead weight tester.

INTRODUCTION

The pressure intensity at any point in static or moving fluid can be measured using various types of pressure measuring instrument. One of these devices is the Bourdon tube  pressure gage. Bourdon-tube pressure gages are most widely used now-a-days because of  their reliability, compactness, low cost and ease of use. t consists of a curved tube of  elliptical cross-section bent into a circular arc as shown in !ig. 1. "hen pressure is applied to the tube, it tends to straighten out, and the deflection of the end of the tube is communicated through a system of levers to a recording pointer. This gauge is widely used for steam and compressed gases. The pressure indicated is the difference between the system pressure and to the external #ambient$ pressure, and is usually referred to as the gauge pressure

!ig. 1% &chematic of a bourdon-tube pressure gage 's the Bourdon tube pressure gage is used extensively, the stiffness of the internal components change from factory setup and therefore calibration is necessary to give correct pressure readings. (alibration means chec)ing the pressure gage readings against a very accurate device. One of the calibration devices that is available in our lab is the socalled *+ead "eight Tester

A%%arat$*

This dead weight pressure gauge calibrator consists of a precision machined piston and cylinder assembly mounted on levelling screws. ' Bourdon gauge is supplied for calibration. The weights supplied are added to the upper end of the piston rod which is rotated to minimise friction effects. The gauge is thus subject to )nown pressures which may be compared with the gauge readings and an error curve drawn.

E!%ermeta1 Pr"'e.$re*

1.

!ill up a cylinder and a connecting hose with water

.

nsert the piston into the cylinder and remove as much air bubble as possible from cylinder and hose

.

/oad weights on the piston in an increment of 0. )g so as to cover the Bourdontube pressure range from 2ero to maximum pressure on the scale

3.

4ead the indicated Bourdon-tube pressure gauge reading. 5rior to ta)ing a reading for each weight rotate the piston to minimi2e friction effect on the reading.

.

'fter the maximum pressure reading is obtained, unload weights from the piston  by the same increment and repeat step 3.

6.

Obtain the calibration curve by plotting the True 5ressure against the Bourdon-tube  pressure gauge reading.

Data aa12**

7ass of the piston % 1 )g (ross sectional area of the piston% 88888888888888 m

7ass of the piston x #9.:1 x 10-$ True 5ressure exerted by piston

; ------------------------------------------------ )<=m  (ross sectional area of piston

 Total mass #weight > piston$ x #9.:1 x 10-$ True pressure exerted by total mass ; ----------------------------------------------------)<=m  (ross sectional area of piston

EXPERIMENTAL DATA

7ass #)g$

True pressure #)<=m$

#1$ 7ass 'dded #)g$

#$ Total mass #)g$

0

1 #piston$

#$ 5ressure exerted by total mass

(alibrated pressure #Bourdon gauge$ #)<=m$ #3$ ncreasing order  of weight

#$ +ecreasing order  of weight

5ercentage of error 

   ? =  

#3$ or #$ − #.$ #.$

     

x100  

#6$ #@$ ncreasing order of  +ecreasing order of  weight weight



La,"rat"r2 re%"rt

1. &how sample calculations . 5lot a graph of bourdon pressure #calibrated $ for increasing and decreasing orders of weight versus true pressure. Axtend the graphs and chec) if they intercept a point of origin. (omment on the difference in the graph profiles and explain the possible reason for the graphs #if so$ not intercepting the origin  point. . 5lot a graph of percentage of error versus true pressure. (ompare and comment on the difference in the percentage of error with respect to true pressure and

La,"rat"r2 re%"rt

1. &how sample calculations . 5lot a graph of bourdon pressure #calibrated $ for increasing and decreasing orders of weight versus true pressure. Axtend the graphs and chec) if they intercept a point of origin. (omment on the difference in the graph profiles and explain the possible reason for the graphs #if so$ not intercepting the origin  point. . 5lot a graph of percentage of error versus true pressure. (ompare and comment on the difference in the percentage of error with respect to true pressure and  briefly discuss factors contributing to such error. 3. 5ropose recommendation to improve the results . Briefly discuss safety measures ta)en during the experiment 6. (onclusions @. 4eferences