Answer / sridhar

if the flow must be maintained in process line, we can use
the double acting control valve. for example,if there is a
purging system for any process control,even if the signal
fails and air fails, the valve should be in same poistion
to maintain the flow in the pipe line for process safety.

Answer / carl_ellis

Part of your problem is your terminology.

Valves are chunks of machined metal and elastomers, valves
are not single action or double action, the actuator that
moves the valve stem is.

So your Google search should be for double action actuator,
which will provide you an answer.

Carl Ellis
Measure First

Answer / afroz

I need answer

what is the formula for calculating milliampere at different pressure points for eg 4-20 ma = 3-15 psi but if i have to check the ma at 4.6 ma?

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Foe selecting control valve if i have the min,normal & max data of flow rate,inlet pressure& outlet pressure,inlet tem.&density than how can i assure that these data are correct,pl. let me know if therew there is any method to check it.& also how we assure that the Cv we get from this data is suitable for valve for controlling require flow.

3 Answers   HPCL,

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