Updated 3/13/2008

Flowmeter Comparison:Procedure

Use the attached illustration of the Flowmeter Demonstration Rig to aid in your set-up.

Figure 1: Flowmeter Demonstration Rig Diagram

Materials

Hydraulics Bench, Flowmeter Demonstration Rig, bicycle pump, purge tube, stopwatch

Setup and Priming the System

  1. Locate the Hydraulics Benchon the 2B level of the ITL near the door of the Machining Studio and place the Flowmeter Demonstration Rig from the 2B60 module storage bay on top of it.
  2. Secure the quick release connector on the inlet pipe to the quick release connector in the top of section of the hydraulics bench by pushing down on the ring, inserting the hose, and releasing the ring. Be sure the connection has locked and the ball bearings are not visible (it may take some force to ensure the connection is secure).
  3. Place the outlet tube from the rig in the volumetric tank of the Hydraulics Bench and secure it so as to ensure water doesn’t spray everywhere during the experiment. This can be easily done by pinning the tube to the wall of the tank using the black ramp.
  4. Turn the flow control valve of BOTH the Hydraulics Bench and the Flowmeter Demonstration Rig completely off (clockwise rotation).Be careful not to apply too much pressure or the pipe fittings could be damaged.
  5. With the motor switch in the OFF position,make sure that the air bleed screw located at the top of the manometer board is fully closed.
  6. Check that the Hydraulics Bench is plugged in and turn the motor switch ON. Confirm pump operation by listening to the motor.
  7. Slowly open the flow valve on the Hydraulics Bench about one and a half turns.The rig should begin filling with water.
  8. Open the flow control on the rig until the top of the rig on both sides of the orifice plate are completely full of water. If this does not happen, try opening the flow control on the Hydraulics Bench a little more (counter-clockwise).
  9. Purge the air out of the system. It is imperative that all bubbles be removed from the manometers for accurate readings.
  10. Place one end of the purge hose (found on the hook on the back of the apparatus)over the air connector (just below the air bleed screw) and point the other end into the bench’s tank.
  11. With one hand holding the tube around the air connector, slowly open the air bleed screw on the Flowmeter Demonstration Rig. Water should drain through the tube and push all the air out of the manometer board.
  12. Once the system is purged of air, completely close the air bleed screw and the flow control valve on the rig. The flow control valve on the Hydraulics Bench should remain open for the rest of the experiment. Remove the hose from the air connector and return it to its hook.
  13. Change the static pressure of the system usingthe hand pump and air bleed screw. This will enable readings of the manometers during high flow rates not to drift off the board as some readings will increase while others will decrease.
  14. Attach the bicycle hand pump on the air connector. To do this, the locking flap on the bicycle pump should be parallel to the pump hose when pushing the pump onto the air connector. Flip the flap down (away from the pump hose) to lock the bicycle pump into place.
  15. Slowly open the air bleed screw and then give about two pumps of air into the system.The goal is to get the eight manometer readings set at approximately 220 to 240 mm H2O.
  16. Once the static pressure reading has been reached, close the air bleed screw.
  17. Disconnect the hand pump and remount it behind the Flowmeter DemonstrationRig.The system is now primed.

Experiment

  1. To aid in data acquisition, construct a table similar to that shown below:

Manometer Readings(mm H2O)
#1#2#3#4#5#6#7#8 / Variable Area
Meter (L/min) / Volume
(L) / Time
(min) / Flow Rate
Q(L/min)
  1. With the system primed, slowly open the flow control valve on the rig.Set the flowrate to a value near 20 L/min as read off the top of the float in the variable area meter.
  2. When the system stabilizes, record the eight different manometer readings in your table as well as the variable area meter reading taken from the top of the float.The units of the manometer board are in mm H20 relative to your datum line.
  3. Measure the flow rate by timing the volume collection.
  4. Close the dump valve via the dump valve handle on the Hydraulics Bench.The fluid will start to rise in the volume measuring tank.
  5. Using the sight tube scale(near the pump ON/OFF switch) and a stopwatch, measure the volume change as a function of time (at least 30 seconds to obtain an accurate flowrate measurement).You will want to use the upper scale. To do this, wait for the water level to reach zero on the upper scale before starting your measurement.
  6. Once you have obtained your timed volume collection – reopen the dump valve.
  7. Lower the flowrate via the flow control valve on the rig.Repeat step 15 &16 to get measurements of each flowmeter for a total of 3 different flowrates (i.e.20, 12, 5 L/min).
  8. For at least one of the flowrates you experimented with in step 17 above, repeat your measurements to get an estimate of random uncertainty in your experiment.
  9. Using your recorded measurements from the manometer, obtain the following at each flowrate:

Venturi reading:Man. 1 - Man. 2

Loss in Venturi:Man. 1 - Man. 3

Loss in variable area meter:Man. 4 - Man. 5

Orifice plate reading:Man. 6 - Man. 7

Loss in orifice plate:Man. 6 - Man. 8

Figure 2: Manometer Setup

*** Remember that units are in mm H2O.Units should be properly converted prior to using any equations.

Clean-up

  1. At the end of your experiment, completely close both the flow control valve on the rig and on the bench and turn the pump motor OFF.
  2. If the Flowmeter Demonstration Rig is being returned to the module storage bay, drain all water possible from the rig first by opening both the flow control valve and the air bleed screw and disconnecting the inlet tube from the Hydraulics Bench. Tilt the rig from side to side to help drain as much water as possible before retuning it to the module storage bay.
  3. If any water was spilled on the floor, please clean it up using a mop and bucket. Thanks!

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