®
M o d e l N o . M E- 8 5 9 8
E x p e r i m e n t
5
Setup
1.
Connect the Quad Pressure
Sensor to your PASPORT
interface (but do not connect
tubing to the pressure ports
yet). If you are using a com-
puter, start DataStudio.
2.
Calibrate the Quad Pressure
Sensor (see Appendix A).
3.
Connect each of the four pres-
sure tubes extending from the
underside of the apparatus to
the ports of the Quad Pressure
Sensor as indicated in Figure
2.
Important:
Do not allow water to enter
the sensor. Ensure that there is no
water near the sensor end of the pres-
sure tubes.
4.
Place the top plate on the
apparatus and secure it with
eight T-knob screws. Tighten
the screws no more than necessary to prevent leaking.
5.
Set up the fluid supply and flow-rate measurement as described in Appendix B.
Procedure
1.
Start fluid flow.
2.
Start data collection on the computer or interface.
3.
Continue data collection while observing the pressure measurements on a graph
display. Obtain a few seconds’ worth of good data before stopping data collection
and fluid flow.
Analysis
1.
View your data on a graph of pressure versus time.
2.
Select a time interval of about 2 seconds in which all off the pressure measure-
ments are relatively clean (though not necessarily constant or noise-free).
3.
Within this time interval, determine the average of each pressure measurement:
P
1
, P
2
, P
3
(and P
4
if you will do the Further Analysis below).
4.
Over the same 2-second interval, determine the average flow rate, R.
5.
If there were no friction or turbulence in the channel, the pressures in both wide
sections (P
1
and P
3
) would be equal; however, you will find that this is not the
case. Because the channel is symmetrical about Point 2, you can estimate the
pressure lost at Point 2 due to friction and turbulence by assuming that it is half
of the pressure lost between Point 1 and Point 3. In other words, if the tube were
Figure 2: Quad Pressure Sensor connected to apparatus
Quad Pressure Sensor
To Quad Pressure
channels:
2
3
4
Fluid flow
1