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4.2
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 "speed"and "direction" control signals) can be accom-
plished by connecting pin 3 of the 9-pin "D" connector to COMMON ( power
ground). The Motorized valve will be given the command to close indicated by
a green light on top of the unit).
Conversely, when the connection is left open or pin 3 remains unconnected
the valve remains active (executes "speed"and "direction" control signals).
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 SMV
valve.
4.3
Valve Purge
At times, it may be necessary to purge the flow system with a neutralizing gas
such as pure dry nitrogen. The SMV valve is capable of a full open condition
for the valve, regardless of setpoint conditions. Connecting the PURGE pin
(pin 7 on 9 pin "D" connector) to ground will fully open the valve.
A red light on top of the valve will indicate an OPEN valve condition, normal
for flow conditions.
Please note that the valve stays OPEN even if power is no longer
applied. To CLOSE the Motorized Control Valve, connect pins 3
and 2.
7
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