Solenoid Valves

Can you explain more about your solenoid valve (SV)? The SVs I am familiar with are fully closed or fully open, but there might be 2-stage SVs with intermediate positions.

Other types of actuators such as motors, diaphragms, and pistons can be arranged for modulating service.

Your question is not clear. Please elaborate

The reason your question is so confusing is that' like others have stated, solenoid operated valves are open or closed. In most control schemes, 100% output calls for an open valve, 0% output calls for a closed valve.

The only exception I can think of is a 'modulated' solenoid, where a signal conditioner box pulses the solenoid's coil with power at a varying high speed rate, with the result that the solenoid and valve 'hang' at some intermediate position between open and closed. Even ASCO, a major US solenoid valve manufacturer calls this a 'proportional' valve (2/2 series, 8260), not a solenoid valve.

So more information is needed from you, specifically,

What is at 50%? Controller output? Positioner output? How do you know whatever it is is at 50%?

What form does 50% take? control air at 12psi? electrical voltage at 50% duty cycle ? 12mA?

What is the format/protocol/procedure for your "solenoid test". What does it read like?

What 'valve stem' are you talking about? The solenoid valves' stem? Which model solenoid are you using that you can view the solenoids' valve stem?

Or is the 'valve stem' on an air operated modulating control valve to which the solenoid controls the air supply?

Is the solenoid a 2 way or 3 way?

Sir,

We call it as an SOV test which is done in the bypass mode keeping the valve in fully open condition, the solenoid used is ASCO -3 way operated solenoid , these test r done on ESD valves.i wanted to know rather y does this test is applicable in gas industries and how does the setting done for the valve not to move when the condition is fully open 100%

Why not ask the individual that approved the test protocol document?

Motorised valves that operate at variable openings, i.e. at other positions than fully closed or fully open, are not normally controlled by solenoids as these are not usually capable of providing the varying signal needed to operate what is a high-investment valve properly. Solenoids operate a lower-value valve to provide an on/off signal, in the main.

With a variable valve at 50% open, its pressure drop vs. flowrate property is used to provide a value that is labelled Cv, which is an inherent property of the valve's behaviour and enables its correct selection during the sizing operation at process mechanical design stage.

Why the Cv is being checked is not clear, for if the plug or the seat wears, the valve will simply move to a position that the actuator considers is less than 50%. Or, another way, 50% on the control signal will give a valve that is passing more fluid than its design intent. This condition can be compensated by putting a little integral action in the 3-term controller that is driving the valve, or by changing-out the worn components for replacements that will give the required performance at 50% open. The purpose of carrying out any testing might be to establish the state of wear before making a decision to strip and replace, or it might be for something else. However, if it is for this operation, it can be determined by looking at process parameters with the valve still installed in the process line. So it must be for something else. Any chance of looking at this conundrum, please, and reporting back?