Testing flow meter cables, Important – Raven Industries SCS 450 User Manual
Page 48
Chapter 7
44
SCS 450 Serial Interface Installation & Service Manual
d.
Spin the turbine to confirm that it spins freely with very little drag inside the turbine hub.
4.
Adjust the turbine hub if necessary. This should be done whenever the transducer assembly is replaced or
the turbine stud is adjusted or replaced.
a.
Hold the turbine hub with the turbine on the transducer.
b.
Spin the turbine by blowing on it.
c.
Tighten the turbine stud until the turbine stalls.
d.
Loosen the turbine stud 1/3 of a turn. The turbine should spin freely.
5.
Reassemble the flow meter.
6.
Use a low pressure (5 psi/34.5 kPa) burst of air to verify that the turbine spins freely. If there is a drag,
loosen the hex stud on the bottom of the turbine hub 1/16 of a turn until the turbine spins freely.
7.
Store the flow meter in an area that prevents it from freezing.
Testing Flow Meter Cables
1.
Disconnect the cable from the flow sensor.
FIGURE 1.
Flow Sensor Connector Cable Connection
Note:
If a +5 VDC voltage reading is not present, disconnect the speed sensor cable. If the flow reading
is restored, refer to the Testing Speed Sensor Extension Cables section on page 46
to test the
speed sensor extension cables.
1.
Enter a METER CAL value of 1 into the console.
2.
Press the TOTAL VOLUME button.
3.
Place the RATE 1/RATE 2/MAN switch in the MAN position.
4.
Turn the boom switches ON.
5.
Create a short between the ground and signal sockets by inserting a small jumper wire or paper clip into
both sockets simultaneously. Each time contact is made, the TOTAL VOLUME reading should increase in
increments of 1 or more. If the TOTAL VOLUME does not increase:
a.
Remove the section of cable closest to the console.
b.
Repeat the ground-signal short test.
•
If the TOTAL VOLUME does not increase, replace the defective cable and repeat the ground-
signal short test.
•
If the TOTAL VOLUME increases, replace the flow sensor.
6.
Perform voltage checks as illustrated in the figure above.
Important:
Re-enter the original METER CAL figure after testing is complete.
Ground
Signal
Power
+5 VDC
+5 VDC