It is recommended that a potentiometer between 5K to 100K ohm and capable of
at least 10-turns or more for adjustment be used. Use the control potentiometer
to command the percentage of flow desired.
Alternatively, a variable 0 to 5VDC or 4 to 20 mA analog signal may be applied directly
to the SETPOINT and COMMON connections of the FMA 5400A/5500A transducer
(see Figure 2-1). Be sure to apply the appropriate signal for the designated jumper set-
tings.
5.5
Valve OFF Control
(Open Collector NPN Compatible)
It may be necessary or desirable to set the flow and maintain that setting while
being able to turn the flow control valve off and on again. Closing of the valve
(without changing the setpoint adjustment) can be accomplished by connecting
pin [12] of the 15-pin “D” connector to COMMON pin [3]. When pin [12] is con-
nected to COMMON, the solenoid valve is not powered and therefore will
remain normally closed regardless of the setpoint. The Motorized valve will be
given the command to close indicated by a green light on top of the unit).
14
Conversely, when the connection is left open or pin [12] remains unconnected the
valve remains active. The valve will remain active when the VALVE OFF pin remains
“floating”. This feature is compatible with open collector NPN transistor switches, as
found in DC output ports of programmable controllers and similar devices.
The simplest means for utilizing the VALVE OFF control feature, is to connect a
toggle switch between the COMMON and VALVE OFF pins of the FMA
5400A/5500A transducer. Toggling the switch on and off will allow for activating
and deactivating the solenoid valve.
5.6
Valve Test/Purge
At times, it may be necessary to purge the flow system with a neutralizing gas such
as pure dry nitrogen. The FMA 5400A/5500A transducer is capable of a full open
condition for the valve, regardless of setpoint conditions. Connecting the OPEN
(PURGE) pin (pin [4] on 15-pin “D” connector) to ground will fully open the valve.
The Motorized Valve: Connect pins [3] and [4] to OPEN the motorized control
valve A red light on top of the valve will indicated an OPEN valve condition,
normal for flow conditions.
NOTE: The motorized control valve stays OPEN even if power is no
longer applied. To CLOSE the Motorized Control Valve, connect
pins [3] and [12].
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