Friction Loss in Pipes and Fitting Lab
Friction Loss in Pipes and Fitting Lab
Overview:
In these experiments you will calibrate a rotometer, calibrate an orifice plate meter and determine
the orifice coefficient, and determine friction factors for a number of pipes and fittings.
The apparatus consists of a mobile centrifugal pump/ feed tank unit that can double as a mixing
tank and a network of pipes and fittings to which pressure taps have been fitted. Flow rate is
principally determined by a rotometer that you must calibrate using the “bucket and stopwatch”
method. An orifice flow meter is also present on a ½ inch stainless steel pipe. A differential
pressure cell (DP cell) is used to measure the pressure difference between taps. The pipes on the
apparatus are listed below:
A- 1” schedule 80 PVC (feed pipe to manifold)
B- ¾” schedule 80 PVC
C- ½” schedule 80 PVC
D- ½” schedule 80 stainless steel (D1- straight pipe, D2- pipe with orifice meter that
connects to pipe F)
E- 3/8” schedule 80 PVC
F- ½” schedule 80 clear PVC (connects to pipe D2)
Standard Operating Procedures and Precautions:
Precautions:
1) Beware of any electrical or trip hazards posed by the cord for the centrifugal pump.
2) You should not operate the mixer for this experiment. However, beware that when
operating equipment exposed rotating shafts, you should not wear loose fitting clothing or
neck ties, and should keep long hair tied back.
3) Wear rubber soled shoes to prevent slipping on the potentially wet floor.
4) The centrifugal pump must not be operated dry or the shaft seals may be damaged
(however the pump may be operated at downstream shutoff for short periods of time).
SOP:
1) Connect the pump to the pipe and fitting apparatus with the connector union if not
already attached.
2) Fill tank approximately 2/3- ¾ full of water from hose.
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Friction Loss in Pipes and Fitting Lab
3) Make sure the return hose is directed into the top of the feed tank.
4) Make sure the valve feeding the centrifugal pump is open.
5) Close all ball valves on the feed manifold except for the valves on pipes A and B.
6) Close the globe valve upstream from the rotometer.
7) Use the motor starter switch (located on tank support frame) to start the pump motor.
8) Open the globe valve until the rotometer shows the maximum possible flow (globe
valve all the way open).
Assignment: (write detailed procedures before lab, and go over with TA or instructor)
1) Measure water temperature (you will want to repeat frequently as temperature may
change throughout the experiment- why?)
2) Calibrate the rotometer at about 10 different points from max flow to zero flow (large
beakers, buckets and graduated cylinders are available for use). Use linear regression in
Excel to determine the relationship between flow rate and % reading on the rotometer
before proceeding further.
3) Calibrate the orifice meter using the DP cell and rotometer (note: be sure to choose
“high” and “low” pressure taps correctly).
4) Measure pressure drop across pipes A, B, C and D1 at enough flow rates to construct
plots similar to the “Moody” of “Darcy” plots- be sure to include both laminar and
turbulent flow. Be sure to use the proper pipe diameter based on schedule number in your
calculations, and estimate surface roughness from an appropriate reference.
5) Measure pressure drop for the 90 degree and 45 degree bends in pipe F in the turbulent
flow regime.
6) Measure pressure drop for the globe valve in pipe D2 for the valve in the fully open
and half open positions.
7) Measure pressure drop in the piping network configuration given to you by the
instructor. (check with the instructor for specific instructions as this part of the assignment
will vary from week to week)
Minimum Report Requirements:
1) Use the “regression” feature of Excel to determine the calibration curves for both the
rotometer and the orifice plate (Note, you will have to make a transformation of the data to
use linear regression on the orifice plate data. . . why?, what is the expected function for DP
vs Q?). Use 95% confidence intervals to determine uncertainty in your calibrations.
2) Determine the “orifice coefficient” from (1).
3) Determine the “valve coefficient” for the globe valve in pipe D2.
4) Determine friction factors for pipes A, B, C and D1. Compare to expected values.
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Friction Loss in Pipes and Fitting Lab
Construct the best graphs you can make (consider carefully how best to do this) to show the
relationships between diameter and pressure drop, diameter and friction factor, and material
of construction and friction factor, expected and experimental values, etc. Discuss fully
and use evidence and your best engineering judgment to explain discrepancies.
5) Any other aspects you think are interesting and important.
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