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2)
3)
Cycle purge. This is done by alternately evacuating
and purging the device for two to four hours with
clean, dry nitrogen or argon.
Purge the device with clean, dry nitrogen or argon for
eight to twenty-four hours.
Evacuate the device for eight to twenty-four hours.
1)
-
Purge reactive gases from the FMA-1900 using one of the
following methods:
3.13.1 Purging Non-reactive Gases
Purge non-reactive gases from the FMA-1900 with clean,
dry nitrogen or argon for a minimum of two hours.
3.13.2 Purging Reactive Gases
“D”
connec-
tor to common through either a mechanical switch or an
open-collector transistor or logic output capable of sinking
at least 4mA (See Appendix B). The maximum voltage
appearing on this pin is 5.0 VDC.
15-pin
setpoint command signal must be above 2% of full
scale or DIP switch 5 must be in the OFF position).
The activation of either the Valve OFF switch or the
Auto-Shutoff function will override the purge command.
To activate purge, connect pin 4 of the
3.13
Purging of FMA-1900 Products
The purge function opens the controller valve completely
for the purpose of purging the meter and for quickly
flushing unwanted gas from the flow path. When the
valve is opened for purging, it allows flows far in excess of
the rated full scale of the controller. Because of the
uncontrolled nature of the purge function, two conditions
must be met before a controller can be purged.
1)
The Valve OFF switch, if it is used, must be in the ON
or open state.
2)
The Auto-Shutoff function cannot be active (the