#Jameel_Academy_Fluid Mechanics_Tests

1. University of Duhok
College of Engineering
Civil Department
Fluid Mechanics – Practical
Fluid Laboratory
A Report About :
Pressure Measurement by weight and
bourdon gauge
Student Name : Jameel Masoud Jameel
Class : B
Date of Experimental : 9 / 10 / 2017
Date of Submitting : 23 / 11 / 2017
Experiment No. : 2

2. Procedure :
1) The weight of piston in each times and it's cross-sectional area must
be written (noted), And Don’t vibrate the gauge machine during
procedure.
2) Prepare some amount of water for test, and Ensure that the
indicator of gauge reading zero pressure.
3) Put some water to fill the gauge pressure testing machine.
4) then put the Piston (1kg) to hollow cylinder. and then excessive
water will be removed when its gain to the overflow level.
5) Then measure the increase pressure in gauge (kN/m2
).
6) Repeat the procedure and reading the pressure with changing in
Weight by adding (0.5 kg ) from previous Weight.
7) When we measure the pressure at 4 kg of piston's mass then
remove the weight (0.5 kg) from each times and measure again the
pressure and named it to decrease pressure. (the result will be
accuracy when decrease pressure and increase pressure of same
weight is equal).

3. Calculations and Results :
We will calculate the true pressure by using this fomula :
True Pressure =
Mass of Piston (Kg) × 9.81 × 103
Area of piston (m2)
Area of Piston is (0.315 × 10-3
m2
) , Weight = Mass × 9.81
For example :
When the mass of piston is 2 kg and area of piston is 315 𝑚𝑚2
,
the true pressure can be calculated as :
True Pressure =
2 kg × 9.81
0.315 × 10−3 m2
= 𝟔𝟐. 𝟐𝟖𝟔 𝐤𝐏𝐚
And the Error of measuring pressure can be determined by using
this formula :
Erorr (%) =
Gauge reading − True pressure
Gauge pressure
× 100
For example :
When 2 kg, gauge pressure is 61 kPa and the true pressure of 2 kg is
62.286 kPa , the error will be :
Erorr (%) =
61 − 62.286
61
× 100 = −𝟐. 𝟏𝟏 % = 𝟐. 𝟏𝟏 %
The negative sign in errors is refer which the true pressure is greater than gauge pressure

4. Detail's Table :
The relationship between True pressure and increase Gauge reading:
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
IncreaseGaugeReading(kPa)
True pressure (kPa)
Including Piston
Weight True
pressure
(kN/m2
)
Gauge Reading
Mass
(kg)
Weight
(N)
Increase
pressure
(kN/m2
)
Errors %
Decrease
pressure
(kN/m2
)
Errors %
1 9.81 31.143 29 7.39% 30 3.81%
1.5 14.715 46.714 46 1.55% 47 0.61%
2 19.62 62.286 61 2.11% 62 0.46%
2.5 24.525 77.857 76 2.44% 77 1.11%
3 29.43 93.429 92 1.55% 92 1.55%
3.5 34.335 109.000 105 3.81% 106 2.83%
4 39.24 124.571 122 2.11% 122 2.11%

5. The relationship between True pressure and decrease Gauge reading:
0
20
40
60
80
100
120
140
0 20 40 60 80 100 120 140
DecreaseGaugeReading(kPa)
True pressure (kPa)

6. Discussion and Conclusion :
In this test we determine the Pressure by using weight and bourdon gauge
and relationship between them, finally we got a result after doing all
procedure accurate which is increasing and decreasing pressure and then
comparing it with true pressure by using the formula and then calculating
the errors from increasing and decreasing pressure, the percentage of
errors in decreasing pressure is smaller than increasing pressure as
shown in detail's table because we have some Deficiencies in test one of
them is the wrongly reading pressure, another one is the pressure
measurement indicator is not in zero reading, its 22 kPa before piston
placed on hollow cylinder therefore after measure each pressure we need
to Subtract 22 kPa , but it doesn’t mean that our test is wrong, because
in every test have some errors but the result will approximately or nearly
to the right value, we know that if we do many tests we will get the right
result.
In conclusion the purpose of this test is to determine the relationship and
calculate the true pressure and gauge pressure, and then determining the
errors that maybe we do, finally we will get and determine the main goal
of this test which is how to use pressure gauge, calculate the pressure
and do the procedure without errors.