Thermodynamics Lab: Calibration of Pressure Measuring Equipment

This report details an experiment conducted to calibrate pressure measuring equipment using two methods: a Bourdon gauge sensor and a semiconductor pressure sensor. The experiment utilizes a TH2 apparatus with a deadweight calibrator to measure pressure, focusing on analyzing the linearity and accuracy of each device. The report outlines the materials and methods, including the setup and procedures for both sensors. Results are presented, comparing experimental data with theoretical values, revealing a 0.003% deviation for the Bourdon gauge and 0.05% for the semiconductor sensor. The discussion emphasizes the importance of priming the equipment for accurate measurements and highlights potential sources of error. The conclusion favors the Bourdon gauge due to its higher accuracy. The report also provides a detailed list of the parts and functions of the TH2 equipment, along with references to relevant literature.

Calibration of Pressure Measuring Equipment 1
CALIBRATION OF PRESSURE MEASURING EQUIPME
Course Name
Professor
Name of School
City
Date

Calibration of Pressure Measuring Equipment 2
Table of Contents
ABSTRACT....................................................................................................................................3
CHAPTER ONE..............................................................................................................................4
1.0 Introduction...........................................................................................................................4
CHAPTER TWO.............................................................................................................................5
2.0 STATEMENT OF THE PROBLEM....................................................................................5
2.1 Project Objectives..................................................................................................................5
CHAPTER THREE.........................................................................................................................6
3.0 Materials and Methods.........................................................................................................6
3.1 Materials............................................................................................................................6
3.2 Methods.............................................................................................................................7
CHAPTER FOUR...........................................................................................................................9
4.0 RESULTS AND DISCUSSION................................................................................................9
4.1 Bourdon gauge sensor:........................................................................................................9
4.5 Semiconductor pressure sensor........................................................................................10
4.6 Discussion............................................................................................................................11
5.0 Conclusion...............................................................................................................................12
5.0 References................................................................................................................................13

Calibration of Pressure Measuring Equipment 3
ABSTRACT
The report evaluates the two different methods utilised in measuring the pressure and calibration
in Thermodynamics. The two devises used for this experiment to measure the pressure are
connected to affixed deadweight calibrator. The objective is to analyse the linearity and accuracy
of the two set of devices that were used in performing the experiment. The report talks in detail
about the procedure used in calibration of the equipment for the purposes of improving its
accuracy.

Calibration of Pressure Measuring Equipment 4
CHAPTER ONE
1.0 Introduction
Pressure given conventionally obtained by the formula P = F / A, is defined as the force
that acts normal to an object’s surface area per unit area. The experiment involved measuring the
pressure variable by utilizing two devices- “TH2 Apparatus”. The apparatus contain two dead
weights and a calibrator that is connected to the pressure measuring devices- “Bourdon Pressure
Gauge” and the “Electronic Pressure Sensor Device”( Maul, 2005, pp. 781-782). For use of the
equipment to be effective, it is necessary for priming of the same equipment (Agrawal, 2008).
When the equipment are primed before use, their accuracy and linearity of measurement of the
experiment improves greatly. The equipment is cleaned using a special equipment in the
laboratory followed by their calibration so as to ensure that the measurement during the
experiment are taken correctly (Avison, & Barham, 2014, pp. 09007).
The figure below is an illustration of experiment setup. The TH2 equipment is used for
calibration of pressure. It compares the theoretic value of pressure to the experimental value. The
accuracy ratio should not be more than 3:1 between the equipment and the theoretic value. The
equipment utilizes weights that are put on the equipment to create pressure since
pressure=force/area. The area is the place where the weight are placed then the force is obtained
from; Force=m*a where a=gravitational acceleration. The different pressures that are known and
fixed from the weights placed on the equipment (deadweight) are generated. The characteristics
of the unit including the linearity and accuracy are then determined by use of a Bourdon pressure
gauge and an electronic pressure sensor.

Calibration of Pressure Measuring Equipment 5
Figure-1 Experimental Setup(Kamen, Kamen, 1988)
The Bourdon gauge together with the pressure sensor is mounted on the manifold block.
A separate reservoir is used to store the hydraulic fluid. The valves are used to enable priming of
the equipment. Hey enable restricted flow of the water for damping and also enable the
connection of other devices for easy calibration of the equipment. The electronic pressure sensor
on the other hand uses a semiconductor diaphragm that deflects when pressure is applied by the
fluid. A voltage output is generated that is proportional to the applied pressure.
CHAPTER TWO
2.0 STATEMENT OF THE PROBLEM
The problem presented herein is that of measuring pressure by use of two methods
that use two different tools. It is therefore a requirement that a laboratory experiment be
conducted so as to calibrate and measure pressure by use of these devices and compare the
results with the theoretical results.

Calibration of Pressure Measuring Equipment 6
2.1 Project Objectives
1. To measure and compare pressure using two devices.
2. To analyse the linearity and accuracy of the two set of devices that were used in performing
the experiment.
CHAPTER THREE

Calibration of Pressure Measuring Equipment 7
3.0 Materials and Methods
3.1 Materials
TH2 Pressure equipment:
Parts and Functions of the TH2
Parts Function (s)
1 Base
plate
Supporting the equipment as a stand so that it is in an upright operational
position.
2 Manifold
block Offering support for the pressure gauge
3 The
Storage Storage of data that is obtained during the calibration process.
4 Priming
vessel Minimizes errors by clearing the system off any blockage
5 The
Bourdon
gauge Used to take the readings for measured pressure
6 The
Pressure
sensor Sensors and indicates the pressure as read by the equipment
7 The
Priming
valve releases all the blockage in the system
8 The
Damping
valve Used to let in air into the system

Calibration of Pressure Measuring Equipment 8
9 An
additional
isolating
valve Isolation of air for purifying
10 The
Precision
ground
piston Used to hold weights
11
Matching
cylinder Used for comparing
12 Weights Create force/pressure
13 Pressure
sensor cable sensing and transmitting of pressure
14 support Offers support for the stand of the equipment
15
Electrical
console Isolation of air for purifying
16 Mains
on/off
switch Switching the equipment on/off
17 Digital
meter used to give the output reading
18 Selector
switch used to witch between Pressure and voltage readings
19 I/O port For connecting to other outside sources
20 Socket For power connection for the equipment
21 Zero
control Adjusting to zero before the readings are taken
22 Span
control Adjusting for the span of measurements to be taken
23
Electrical
output
(OUTPUT) Used to give output
24 Power
input Used to provide power for the equipment
25 CONT Used to protect the equipment from excess power supply
26 O/P Used to protect the electrical output
27 Mains
lead Supply power to the equipment
28 Quick Used to quickly release the valve coupling
Table 1: List of parts and functions (Selvik, et al., 1983, pp. 343-352)

Calibration of Pressure Measuring Equipment 9
A= d2/4
Figure 3.1 : mechanism of dead weight calibrator (Balling Jr, & Cerveny)
3.2 Methods
The procedure for the experiment involved the use of two equipment. The process followed is
thus outlined as below:
A) For the Bourdon gauge sensor :
1) Calibrate the Bourdon gauge
2) Decrease friction loss achieved by spinning the piston (Bonnar, 1956, pp. 351-359)
3) Take the readings and or measurements of angle in degrees and pressure for piston I
Newtons
4) Slowly add 0.5 kg weights to the piston, afterwards take readings
5) Calculate the theoretical force and pressure for each of the reading. Compare with
the experimental results
6) Take off all the weights, repeat experiment for accuracy (Edmund, 1968).
B) For the Semiconductor pressure sensor:
1) Remove all the weights from the piston
2) Calibrate the semiconductor, do this until the optimum zero pressure can be read.
3) Repeat steps 1 and 2 taking readings of voltage and pressure at an increment of 0.5
kg.
4) Repeat the experiment to obtain average readings (Parr, 2011).

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CHAPTER FOUR
4.0 RESULTS AND DISCUSSION
4.1 Bourdon gauge sensor:
The results of the first method, the Bourdon gauge sensor as a device to measuring pressure are
indicated as below and the graph shown. From the results, it is evident that there is a linear
increase in both the pressure at is applied on the device and the pressure indicated by the device.
On average, the rate of increase is 40 by increase in 0.5 kg of applied pressure. Comparing the
results with theoretic results, the percentage difference is 0.003% (Hay, 1999).
Table 2: pressure results to applied masses

Calibration of Pressure Measuring Equipment 11
Graph 1: Pressure vs Applied Mass
4.5 Semiconductor pressure sensor
From the table below, the results indicate an increase in the equipment pressure with increase in
the pressure applied. The semiconductor pressure Ps however deviates at a certain point and the
linearity is withdrawn as indicated by the graph 2. As more mass is applied the deviation from
linearity of the results and the graph increases. The percentage difference for this equipment in
terms of the comparison of applied pressure and equipment pressure Ps is 0.05%. The
semiconductor pressure on average becomes more than the applied pressure. To cater for this
difference, a formula is applied (Mizuno, 1992):
%difference = 100% x theoretical – experimental / theoretical value

Calibration of Pressure Measuring Equipment 12
Table 3: semiconductor pressure vs voltage results (Webster, 1998)
Graph 2: Pressure against Applied Mass
4.6 Discussion
1. Priming of the equipment is necessary to ensure that any blockage in the system is
removed for effective functioning of the equipment. It should be done before
commencing of the experiment so as to avoid recording errors.
2. The pressure gauge and pressure sensor need to calibrate in order to determine the
accuracy of the equipment. Essentially calibration enables the comparison of the