Switch valve issue
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The control valve is a air-actuated valve; it was found that even when the air supply was cut off, the valve remained open. With it turned off, the gas supply valve remains closed – where lies the fault?
Is it confirmed that it is a pneumatically operated valve, and it remains open even when there is no air supply? How is the accident status selected: to remain as is or switch to accident mode?
Unloading valve: in case of failure, it should be turned off, not kept open
The requirement is shutdown in case of a fault, but what is actually included in the purchase? Check the accompanying documents
If it is a pneumatically operated valve, and the valve remains open even when the air supply is lost, it indicates that either the valve or its actuator is stuck
The opening and closing requirements for this pneumatic valve depend on the solenoid valve in the control air circuit in order to be implemented. The energized/de-energized state of this solenoid valve can control its on/off operation. To release the pressure of the gas at the valve head, it is necessary to eliminate all of this pressurized gas, and this can be achieved by using springs or by altering the pressure on both sides of the cylinder through solenoid valves.
This is likely not a pressure release valve; it’s a double-acting valve. The valve closes in the event of a gas supply failure, and opens when gas is supplied; it contains a spring that allows it to return to its original position in the absence of a gas source. It is a single-acting valve. A double-acting valve can only remain in place when the air supply is lost; it cannot hold its position, and there is no spring inside the cylinder.
No lockout valve? That’s when it gets stuck
1. Is there a lockout valve? 2. Is it a double-acting cylinder?
Either it’s not the pressure release valve, or it’s stuck