How do we know the SOV is failure
How do we know the SOV is failure
(OP)
There are some critical interlock loops in our plant.
They were designed by 2 of 2 for DO TYPE point, that means
the loop have 2 solenoid valves for a device to prevent shutdown the plant if a solenoid failed.
My question is how do we know the solenoid valve is dead since the other one still work. Except to touch the solenoid to check the coil, what can I do?
thanks!!
They were designed by 2 of 2 for DO TYPE point, that means
the loop have 2 solenoid valves for a device to prevent shutdown the plant if a solenoid failed.
My question is how do we know the solenoid valve is dead since the other one still work. Except to touch the solenoid to check the coil, what can I do?
thanks!!





RE: How do we know the SOV is failure
I would look at flow meters or some similar device to check for flow out the output port rather than checking solenoid temperature or coil current since both could check fine but the valve could still stick.
RE: How do we know the SOV is failure
There are switches like that using at Magnetic Level switches, and switches used as suppliment to magnetic level indicators.
The other option is to have a position switch for the actuator the solenoid is operating or pressure or flow swich to check the flow or pressure the solenoid is causind when activated.
RE: How do we know the SOV is failure
with turbines you block the trip valve and test the ability of the solenoid to unload the throttle valve actuator. with large control valve you monitor valve position or an appropriate process variable.
There are some SOV's that are fail safe. Actually the fall in the category of motorized valves, but the inlude valve position switches etc. These are used in the valve trains for fired heaters and burners (Maxon Valves etc.).
RE: How do we know the SOV is failure
RE: How do we know the SOV is failure
These critical loops do not allow to do online test.
It means that you can not close or open pipe(process) valve
during operation. That is why we design 2 of 2 logic solenoid valve interlock loops to minimize false shutdown.
So we have to monitor the 2 solenoid valves, make sure their functions are OK.
I will install the flow and pressure measurement between the
SOV. Flow one is to detect master SOV,and pressure is monitor redundant one.
Does anyone have such installation experience, please give me advices. Are these devices avaliable in instrument line?
RE: How do we know the SOV is failure
They are not cheap but are excellent if online testing is required.
The Asco system can be supplied with its own PLC, pressure switches and extra testing solenoid. I would check Asco's website for info.
RE: How do we know the SOV is failure
John