PASCO ME-8598 Venturi Apparatus User Manual
Page 11
®
M o d e l N o . M E- 8 5 9 8
A p p e n d i x B : F lu i d S u p p l y a n d F l o w R a t e M e a s u r e m e n t O p t io n s
11
Open the clamp to let some water through the apparatus; then close it. Initially, there
will be air in the apparatus; tilt it so that the air moves to the outflow port. Let some
more water through to flush out the air. Repeat this process until all air has been
removed from the apparatus and inflow tubing. Do not let the reservoir run empty, or
new bubbles will enter. Close the clamp. Refill the reservoir.
Water-flow Measurement Method 1: Motion Sensor
In this method a motion sensor measures the velocity of the descending water surface in the res-
ervoir.
1.
Set the switch on the motion sensor to the near-range setting.
2.
Clamp the motion sensor above the reservoir. Position the sensor very close to
the top of the reservoir so it will measure the distance to the surface of the water
(see Figure 9). The water surface should be at least 15 cm from the sensor.
3.
Test the setup: Start data collection and start the water flow. Look at velocity ver-
sus time data on a graph display. Adjust the position and angle of the sensor so
that you get good velocity data as the water drains. (It is not necessary to get
good data over the entire range of water level, since you will only need about 2
seconds’ worth of data.) Stop water flow and refill the reservoir. Delete your test
data.
4.
Create a flow-rate calculation: In the DataStudio Calculator window (or GLX
Calculator screen) enter the following definition:
R = v * A
Define the variable v as the velocity measurement. Define A as a constant equal
to the horizontal cross-sectional area of the inside of the reservoir. Measure the
area in units of m
2
. In this way, R is calculated in units of m
3
/s.
Water-flow Measurement Method 2: Rotary Motion Sensor
In this method a rotary motion sensor measures the velocity of the descending water surface in
the reservoir.
Parts Required or Recommended
Part Number
Motion Sensor
PS-2103
Water Reservoir (or other narrow, straight-sided container)
ME-8594
Equipment for mounting sensor:
Multi clamp
SE-9492
Mounting rod
SA-9242
Parts Required or Recommended
Part Number
Rotary Motion Sensor
PS-2120
Water Reservoir (or other narrow, straight-sided container)
ME-8594
Float (such as a piece of wood)
Small weight (weighing less than the float)
Equipment for mounting sensor:
Multi clamp
SE-9492
Mounting rod
SA-9242
Figure 9: Motion
sensor and water
reservoir
Rotary
motion
sensor
Float
Weight
Figure 10: Rotary
motion sensor and
water reservoir