Fluid Components International FLT Series - Manual (Page 60)

FLUID COMPONENTS INTL APPENDIX D - TEMP COMP
FLTÔ Series FlexSwitchÔ D - 2 Doc. No. 06EN003286 Rev. -
Procedure
1. Turn off the instrument power. Remove the control circuit form the socket.
2. Write down where the heater wattage control jumper is located in the area of the upper left hand side of the
control circuit. Remove the heater wattage control jumper and set it aside. Refer to Figure 3-1 for the jumper
location.
3. Remove jumpers J10 and J11 at the lower side of the control circuit and set them aside.
4. Connect the DMM from TP1 (by J10), to the left jumper post of J10. Set the DMM to ohms. See Figure 3-2
for component placement.
5. Adjust potentiometer R5 (bottom center of the control circuit) until the DMM reads the ohm value for R5 as
shown on the Temp Comp calibration sheet that is in the plastic page protector in the back of this manual.
6. Remove the DMM, and reconnect it between TP2 (by J11), and the right jumper post of J11. Figure 3-1 shows
jumper post location.
7. Adjust pot R8 (below the yellow LED) until the ohm value for R8 is as shown on the Temp Comp Cal sheet.
8. Remove the DMM and reinstall jumpers J10 and J11. (Leave the heater jumper removed.)
Note: Steps 10 through 13 are the flow element balance procedure required to complete the Temp Comp
restoration.
9. Connect the DMM to P1 (the adapter cable on older control circuits) with the positive lead connected to
position 2 (red wire on older control circuits) and the negative lead connected to position 2 (blue wire on older
control circuits). Re-install the control circuit on the socket. Set the DMM to volts DC.
10. Turn on the instrument power and wait fifteen minutes for the instrument to stabilize. During this time make
sure that the process media is flowing or the sensing elements are submerged. Do not make the following
adjustment in still gas.
11. Adjust potentiometer R13 (next to R8) until the DMM reads 0 volts ±5mV.
12. Turn off the instrument power and remove the DMM. Re-install the heater jumper in its original position.
The Temp Comp adjustments are now restored. Turn on the power and make sure the instrument is functioning
properly. Make adjustments to the alarm set points if needed.
Field Temp Comp Calibration
If the application of the instrument changes the Temp Comp may need to be re-calibrated. An example of when
the Temp Comp needs to be re-calibrated is as follows: The process media is gas, the factory set Temp Comp is 40
to 140 °F. The instrument is then placed in an application that varies in temperature from 300 to 400 °F. In this
case the instrument's accuracy would be greater with a new Temp Comp calibration performed.
Another example of where the accuracy will be affected and a Temp Comp calibration would need to be done is
when the process media is changed, i.e. from water to heavy oil.
Temp Comp calibration is possible to do in the field if the test conditions are met and the data is measured
correctly. However, in many applications it is difficult to achieve these parameters and it is easier to have the
switch factory calibrated. To do the procedure the following parameters are required:
• The maximum temperature range does not exceed 100 °F.
• The maximum temperature does not exceed the instruments rated maximum temperature.
• The velocity at which the switch will alarm needs to be known.