AL Maaref University

Faculty of Engineering

Course Code: MEE280L

Course Title: Fluid Lab

Experiment 4
Losses in a Pipe System
Part 3

Instructor:

Group Number:
Students Name: Yehya L Roz

Date of Testing: 22/3/2024

Date of submission: 2/4/2024
AL Maaref University
Faculty of Engineering

Table of Contents
1 Objective: ....................................................................................................................... 3

2 Theoretical Background: ................................................................................................ 3

a) Pressure loss through pipe .......................................................................................... 3

b) Shutoff Devices .......................................................................................................... 4

3 Test Procedure ................................................................................................................ 5

a) Apparatus: ................................................................................................................... 5

b) Procedure .................................................................................................................... 7

c) Tasks: .......................................................................................................................... 7

4 Results and Discussion ................................................................................................... 8

a) Part A: Coefficient of resistance for pipe shutoff valves............................................ 8

b) Part B: Opening characteristics of shut off valves ..................................................... 9

5 Conclusion .................................................................................................................... 10

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1 Objective:

• Measuring pressure/head losses in pipe shutoff valves.

• Compare theoretical and experimental results.

2 Theoretical Background:
a) Pressure loss through pipe

For turbulent pipe flow, the flow is considered steady at Reynolds’ numbers of Re > 2320.
The pressure loss 𝑃𝑣 (Pa) is calculated as follows:

𝜆. 𝑙 𝜌. 𝑉 2
𝑃𝑉 =
𝑑 2
Where, 𝑙 (m) is the pipe length, 𝜆 is the coefficient of pipe friction, d (m) is the pipe’s
internal diameter, V (m/s) is the flow speed, ρ (kg/m3) is the water density which is a
function of water temperature (At 20˚C water temperature, ρ = 998,2 kg/m3 ) and 𝑔 (m/s2)
is the gravitational acceleration 𝑔 = 9.8 m/s2.

The head loss ℎ𝑣 (m) is calculated as follows:

𝜆. 𝑙 𝑉 2
ℎ𝑉 =
𝑑 2. 𝑔

The Reynolds’ number (Re) is calculated as:

𝑉𝑑
𝑅𝑒 =
𝜈

Where, d (m) is the pipe internal diameter, V (m/s) is the flow speed and ν (m2/s) is the
kinematic viscosity of water which is a function of water temperature (At 20˚C water
temperature, ν= 1.004x10–6 m2/s.

For laminar flows where Re<2320, 𝜆 is calculated as:

64
𝜆=
𝑅𝑒
For turbulent pipe flow (Re > 2320) the pipe friction coefficient (λ) depends on the pipe
wall roughness (k) (k=0.001mm for smooth PVC pipe) and the Reynolds’ number (Re).

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For hydraulically smooth pipes (Re < 65d/k) and Reynolds’ number in the range of 2320
< Re < 105000, the pipe friction coefficient is determined using the Blasius formula:
0.3164
𝜆= 4
√𝑅𝑒
For rough pipes (65d/k < Re < 1300d/k) the pipe friction coefficient is read from Moody
diagram or evaluated using Colebrook formula:
2.51 0.27𝑘 −2
𝜆 = [2 × log⁡( + )]
𝑅𝑒√𝜆 𝑑
The flow speed V (m/s) is calculated from the volumetric flow V̇(m3/s) and the pipe cross-
section d (m).
4V̇
𝑉=
𝜋𝑑 2
Where, ℎ𝑣 (m) is the head loss through the system (pipe and fitting), g (m/s2) is the
gravitational acceleration g=9.8 m/s2, V (m/s) is the total flow speed, λ is the coefficient
of pipe friction, 𝑙 is the pipe length between the measuring connections, and d (m) is the
pipe internal diameter
b) Shutoff Devices

The coefficient of resistance (𝜁) is given by:

2. ℎ𝑉 . 𝑔 𝑙
𝜁= 2
−𝜆
𝑉 𝑑
Where, ℎ𝑣 (m) is the head loss through the system (pipe and valve), g (m/s2) is the
gravitational acceleration g=9.8 m/s2, V (m/s) is the flow speed, λ is the coefficient of pipe
friction, 𝑙 is the pipe length between the measuring connections, and d (m) is the pipe
internal diameter.

The slanted seat valve has a significantly high coefficient of resistance in the range of 𝜁 =
1.5-2.
The socket shut-off gate valve has a coefficient of resistance in the range of 𝜁 = 1-1.5.

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3 Test Procedure
a) Apparatus:

The apparatus used in the experiment is shown in figure 1 and the basic bench is shown
in figure 2.

Figure 3.1 Components of experimental apparatus (HM 150.11)

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Figure 3.2 Basic bench (HM 150)

1. Annular chambers with pressure tapping
2. Ball valves for shutting off part sections
nipples
3. Back wall 4. Double pressure gauge
5. Inlet (concealed) 6. Tubular steel frame with suction pads
7. Flow measurement devices 8. Adjustable measuring section
9. Shut-off devices 10. Drain
11. Sump tank 12. Sliding valve
13. Remote sight gauge 14. Volumetric measuring tank with channel
15. Water supply connection for accessories
16. Diverting cap
without pump
17. Connecting piece for pump 18. Switch box
19. Flow control valve 20. Overflow pipe
21. Water supply connection for accessories
22. Submersible motor driven pump
with pump
23. Drain cock I to IV Measuring sections

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b) Procedure

1. Perform venting on the pressure gauges.

2. Set zero position on the pressure gauge
3. Adjust the desired flow using the inflow valve
4. Read off differential pressure as difference in height between the two water
columns of pressure gauge (mm wc).
c) Tasks:

i. Part A:
1. Enter the measured results into table 1.
2. Calculate flow speed, Reynold number and friction coefficient then enter the
results into tables 2 and 3.
3. Evaluate the coefficient of resistance.
4. Compare with the values in literature.
ii. Part B:
1. Enter the measured results into table 4
2. Draw characteristics curve of flow rate vs. revolutions.
3. Analyze the curves.

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4 Results and Discussion

a) Part A: Coefficient of resistance for pipe shutoff valves

Table 4.1 shows the results of the head loss of the shutoff valves.

Table 4.1. Measurement results of part A

Measured Flow Measured inlet Measured outlet Measured

Fitting
rate (L/min) head (cm) head (cm) head loss (cm)

Slanted valve 28 87 31 56

Socket valve 25 93 25 68

Table 2 shows the speed and the Reynolds number of each case:

Table 4.2. Calculation of flow speed and Reynold number

Internal Measured Flow Rate

Length Flow speed Reynolds
Fitting diameter
(mm) (L/min) (m3/s) (m/s) Number
(mm)

Slanted
17 205 28 4.66 × 10−4 2.05 34711
valve

Socket
15 280 25 4.16 × 10−4 2.35 35109
valve

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Table 3 shows the calculation of coefficient of resistance for each valve.

Table 4.3. Coefficient of resistance for each valve

Fitting Pipe friction Measured head loss Coefficient of

coefficient (m) resistance

Slanted valve 0.0231 0.56 2.33

Socket Valve 0.0231 0.68 1.9

It can be seen from table 4.3 that the socket valve has a lower coefficient of resistance
as expected. However, the coefficient of resistance for both valves fall slightly out of
the range found in literature. The reasons of the errors include:

1. Instrumental error happens when the instruments being used are inaccurate
2. Human error is due to carelessness or to the limitations of human ability
3. Estimation error can occur when reading measurements on some instruments.

b) Part B: Opening characteristics of shut off valves

Table 4.3 shows the measured results of the volumetric flow rate versus number of
revolutions.

Table 4.4. Measured results

Slanted valve Socket valve

Revolutions
Measured flow rate (L/min) Measured flow rate (L/min)

0 0 0

0.5 9.6 8

3 20 26

5 24 36

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Figure 4.1 shows the characteristics curve of each valve.

Characteristics Curve
40

35

30
FLOW RATE (L/MIN)

25

20

15

10

0
0 1 2 3 4 5 6
REVOLUTIONS
Slanted valve Socket valve

Figure 4.1.Flow rate vs. revolutions for each valve

As shown in figure 4.1, as the number of revolutions increases, the flow rate increases for
both valves.

It can also be seen that the socket valve offers a greater flow rate at the same number of
revolutions. However, the slanted valve is more suitable for applications where adjusting
the flow rate slowly is required.

5 Conclusion
It can be concluded that:

1. Slanted valve has a higher coefficient of resistance than socket valve.

2. Slanted valve has a lower flow rate than socket valve at the same number of
revolutions. Thus, it’s more suitable for applications where adjusting the flow rate
slowly is required.

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