Omega fma 1400 User Manual
7.3.2 ZERO Adjustment
Shut off the flow of gas into the Mass Flow Meter. To ensure that no seepage or
leak occurs into the meter, it is good practice to temporarily disconnect the gas
source. Using the multimeter and the insulated screwdriver, adjust the ZERO
potentiometer [R29] through the access window for 0 VDC (or 4 mA respectively)
at zero flow.
leak occurs into the meter, it is good practice to temporarily disconnect the gas
source. Using the multimeter and the insulated screwdriver, adjust the ZERO
potentiometer [R29] through the access window for 0 VDC (or 4 mA respectively)
at zero flow.
7.3.3 25% Flow Adjustment
Reconnect the gas source. Using the flow regulator, adjust the flow rate to 25% of
full scale flow. Check the flow rate indicated against the flow calibrator. Adjust the set-
ting for potentiometer [R21] by using the insulated screwdriver through the access
window, until the output of the flowmeter reads 1.25VDC
full scale flow. Check the flow rate indicated against the flow calibrator. Adjust the set-
ting for potentiometer [R21] by using the insulated screwdriver through the access
window, until the output of the flowmeter reads 1.25VDC
+
37mV (or 8mA
+
0.12mA).
7.3.4 50% Flow Adjustment
Using the flow regulator, increase the flow rate to 50% of full scale flow. Check the
flow rate indicated against the flow calibrator. Adjust the setting for potentiometer
[R45] by using the insulated screwdriver through the access window, until the out-
put of the flowmeter reads 2.50VDC
flow rate indicated against the flow calibrator. Adjust the setting for potentiometer
[R45] by using the insulated screwdriver through the access window, until the out-
put of the flowmeter reads 2.50VDC
+
37mV (or 12mA
+
0.12mA).
7.3.5 75% Flow Adjustment
Increase the flow rate to 75% of full scale flow. Check the flow rate indicated
against the flow calibrator. Adjust the setting for potentiometer [R44] by using the
insulated screwdriver through the access window, until the output of the flowme-
ter reads 3.75VDC
against the flow calibrator. Adjust the setting for potentiometer [R44] by using the
insulated screwdriver through the access window, until the output of the flowme-
ter reads 3.75VDC
+
37mV (or 16mA
+
0.12mA).
7.3.6 100% Flow Adjustment
Increase the flow rate to 100% of full scale flow. Check the flow rate indicated
against the flow calibrator. Adjust the setting for potentiometer [R43] by using the
insulated screwdriver through the access window, until the output of the flowme-
ter reads 5.00VDC
against the flow calibrator. Adjust the setting for potentiometer [R43] by using the
insulated screwdriver through the access window, until the output of the flowme-
ter reads 5.00VDC
+
37mV (or 20mA
+
0.12mA).
Repeat steps 7.3.3 to 7.3.6 at least once more.
7.4
Calibration of FMA 1400 Mass Flow Controllers
All adjustments in this section are made from the outside of the meter, there is no
need to disassemble any part of the instrument.
need to disassemble any part of the instrument.
FMA 1400 Mass Flow Controllers may be field recalibrated/checked for the same
range they were originally factory calibrated for.
range they were originally factory calibrated for.
7.4.1
Disable Solenoid Valve
Remove the round plastic cap on top of the solenoid valve. Turn the set screw on
top of the valve counterclockwise until it stops, to open the valve. Set the valve
into PURGE mode. This step essentially bypasses the flow control properties of
top of the valve counterclockwise until it stops, to open the valve. Set the valve
into PURGE mode. This step essentially bypasses the flow control properties of
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