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If a gas other than the calibration gas is used then the adjusted maximum
(full scale) flow for the unit should be calculated using the K Factor for
that gas (see section C3 above).
A zero or negative set-point voltage will cause the solenoid valve to close
fully. Whilst closed, the valve is configured to withstand pressures up to 60
psig (higher pressures on request).
Caution: The flow controller valve will open if the pressure
exceeds 60psig. For safety it is recommended that a separate
positive shut-off valve is installed upstream of the controller.
5.
Changing The Flow Rate Set-Point – FMA3400/3400ST Series
Only
On the FMA 3400/3400ST Series the set-point may be input from an
external source or be supplied internally.
For an external set-point, dip switch 1 should be OFF and dip switch 2
ON. See section C4 above for details of how to adjust the set-point using
an external voltage source.
For an internal set-point, dip switch 1 should be ON and dipswitch 2 OFF.
Adjustment of the internal set-point is made by turning the coarse and fine
set-point potentiometers on the front panel of the display, with the gas is
flowing, until the desired flow rate is achieved.
FMA 3400/3400ST Series Set-Point Potentiometers
6.
Power Save Mode.
To improve valve performance and reliability over time, the FMA
3200/3400 Series features a Power Save Mode. This is activated after a
prolonged application of a zero or negative set-point. When a control
voltage greater than 0 VDC is applied after the Power Save Mode has been
initiated there may be a short delay (1-2 secs) before the valve actuates.
M-4271/0707, pg. 16 of 26
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