To determine minor losses due to a pipe bend by using fluid friction apparatus.

MINOR LOSSES IN THE PIPE SYSTEM

Object: To determine minor losses due to a pipe bend.

Apparatus:

fluid friction apparatus; hydraulic bench; and stopwatch.

Fig. Fluid friction apparatus

Theory:

The minor loss due to a pipe bend is a function of the velocity head and is written as

V 2

where

h  K

(1)

hl = loss of head due to pipe bend

V = velocity of flow = Q/A

2

3.1422

where,Area of flow =

A d

(1.7)

 2.27 cm

(since d = 17 mm = 1.7 cm)

Putting values in Eq.(1),

K  2g V 2

.hl

2  981

(Q / 2.27)2

.hl

 10108.2 hl

(2)

But the loss coefficient in the case of pipe bend is a function of bend radius (r) and inside diameter of the bend (d), as shown below

In the Fluid friction apparatus, r = 3.0 cm and d = 1.7 cm, i.e. r/d = 1.76, hence Kb = 0.2.

Procedure:

Fill the tank of the hydraulic bench with clean water.
Connect the fluid friction apparatus with the hydraulic bench.
Open the valve(s) that allow flow to the section under consideration and close all the irrelevant valves of the pipe friction apparatus.
Connect the two ends of the tubes to the pressure-tapping nipples at either side of the pair of pipe bends and manometer.
Slightly open the flow control valve on the hydraulic bench.
Remove air bubbles from the tubes by opening the vent valve and drain valves of the differential manometer.
Read the heads in the monometers corresponding to the pressure along the entry and exit of the elbows.
Collect water in the volumetric measuring section of the hydraulic bench. Read the volume collected as well as the time taken to collect that volume of water.
Open the flow control valve at the hydraulic bench slightly more to take new readings.
Repeat steps 7 and 8 to observe new readings.
Carry out computations as per the table below and compare the average value of Kb for the pipe bend with that given in the literature, i.e., Kb = 0.2.

Observations and Calculations:

Comments:

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