Fluid Components International RF83 Manual Operation - Manual (Page 3)

Doc. No. 003147 Rev. B 3 - 3 Model RF83 Flow Switch
CHAPTER 3 - OPERATION FLUID COMPONENTS INTL
Alarm B Set Point Procedure
1. Flow the pipeline at the desired reverse rate of flow.
2. Apply power to the instrument and allow 15 minutes for the sensing element to become active and stabilize.
3. Locate the potentiometer (R20) and the green LED on the control circuit. See Figure 3-1 for the potentiometer
location.
4. Choose A or B.
A. Detecting Reverse No Flow or Reverse Decreasing Flow Rate
If the LED is off, turn the potentiometer clockwise until the LED turns on. If the LED is on, turn the potentiometer
counterclockwise until the LED turns off, then turn the potentiometer clockwise until the LED just turns on. With
the LED on, turn the potentiometer slowly counterclockwise until the LED just turns off. Turn the potentiometer
one-half turn past the point at which the LED just turns off. Be aware that the potentiometer may have up to one
quarter turn of hysteresis. If the mark is overshot, the procedure should be repeated. See Figures 3-1 and 3-2 for
potentiometer position and curve results.
B. Detecting Maximum Flow or Increasing Flow Rate
If the LED is on, turn the potentiometer counterclockwise until the LED turns off. If the LED is off, turn the
potentiometer clockwise until the LED turns on, then turn the potentiometer counter clockwise until the LED just
turns off. With the LED off, turn the potentiometer slowly, clockwise until the LED just turns on. Turn the
potentiometer one-half turn past the point at which the LED just turns on. Be aware that the potentiometer may have
up to one quarter turn of hysteresis. If the mark is overshot, the procedure should be repeated. See Figure 3-1 and
3-2 for potentiometer position and curve results.
BALANCING
The balance number is the resistance difference between the two RTDs (A and B) when the heaters are disconnected.
The balance number is recorded on the edge of the control circuit on a white block with the lettering "BALANCE
NO." written above it.
Generally it is not necessary to obtain the balance number for an application which requires only a switch. However,
for detecting flow direction a precise balance is required since either a small positive or negative voltage output is
used as the indicator.
Balancing is usefull to obtain a calibration curve for the instrument, it is essential to balance the control cirucit. The
accuracy of the calibration is dependent on an accurate balance number. Balancing is also needed if the instrument
switch points are going to be adjusted by numerical values.
Balance the instrument when the balance number can not be found or if the accuracy seems to be incorrect.
Delta R, the difference between the sensor A and sensor B RTDs is used for balancing. Balancing the voltage
(Ohm's law V=I x R) to zero is accomplished by making the difference between the two RTDs zero.
Determining The Balance Number:
Setup Required
FCI FM71D Calibrator
Sensor immersed in process media at zero flow
Power source to power up the switch circuit board
1. Verify the sensor mounting in the process line is correct. Insure there is a no-flow condition in the process line.
2. Verify the correct wiring configuration and then disconnect the heater circuits.
3. Connect the FM71D calibrator (terminal 7,8 and 9 which is labeled on the FM71D calibrator) to the control
circuit, apply power to the instrument.