MEHB221 Fluids Mechanics Lab 2015

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Experiment No. 6

HEAD LOSS DUE TO PIPE FITTING

Objectives

To obtain a series of readings of head loss due to pipe fitting at different flow rates and to

determine the Loss Coefficient for sudden contraction and sudden enlargement of pipe

fitting.

Apparatus

Fluid Friction Apparatus, FM100.

Hydraulic Bench, FM110.

Summary of theory

Most pipe systems consist of more than straight pipes. The additional components like

inlet, outlet bends valves and etc. add to the overall head loss of the system. This head loss

will lead to pressure drop. In selecting pump, it is necessary to know about the pressure

drop.

Head loss due to overall piping system is called major loss while head loss due to bends,

elbow, valve and fitting is called minor loss.

Losses can occur because of a change in pipe diameter. The loss of coefficient for a sudden

contraction, K is the function of the area ratio, A2/A1. This is shown in Figure 1. The value

of K changes gradually from one extreme of a sharp-edged entrance to the other extreme

of no area change. The loss coefficient for a sudden enlargement is the function of area

ratio of A1/A2. This is shown in Figure 2.

Procedures

This experiment is to study the effect of sudden contraction and sudden enlargement on

pipe setting towards the head loss.

For this experiment, determine:

i. Velocity head (hv). ii. Head loss (h) in mH2O.

Plot the graph:

i. Head (h) versus velocity head (hv) for sudden contraction (Graph 1). ii. Head (h) versus velocity head (hv) for sudden enlargement (Graph 2).

iii. Draw a best fit line (straight line) through Graph 1 and Graph 2 and state the slope on the graphs.

MEHB221 Fluids Mechanics Lab 2015

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From the results,

i. Explain about head loss in pipe (including head loss due to pipe fitting). ii. Discuss Graph 1 and Graph 2.

iii. Calculate the experimental value for loss coefficient, K using Graph 1 (for sudden contraction) and Graph 2 (for sudden enlargement).

iv. Find the theoretical value for loss coefficient, K (use Figure 1 and Figure 2). v. Compare and discuss the theoretical and experimental values for K.

vi. List the possible sources of errors and safety precaution.

Precautions on Handling Equipment

Study the apparatus and understand the system; direction of flow, open/closed valve, contraction and enlargement manifold, etc.

Do not operate the pump when there is no liquid in the pipeline. It will cause serious damage to the pump.

Monitor the water level in the measuring tank. Avoid any overflow of water.

MEHB221 Fluids Mechanics Lab 2015

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MEHB221 Fluids Mechanics Lab 2015

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Figure 3: Unit Construction for Fluid Friction Measurement Apparatus (Model: FM100)

1. Smooth Bore Pipes (6mm, 10mm, 17mm) 6. Outlet Control Valve

2. Artificial Roughen Pipe (17mm) 7. Inlet Isolating Valve

3. Manometer 8. Sudden Contraction (10mm)

4. Gate Valve 9. Sudden Enlargement (25mm)

5. Globe Valve 10. Differential Pressure

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