How can a double-acting cylinder valve function as a fault switch?
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Are there any other ways besides using a gas storage tank?
For double-acting actuators, to implement a fault position switch, air tanks are basically used in all cases, whether it’s domestic or imported valves; I have not seen any other methods.
The actuator of the valve is controlled by a solenoid valve, and the opening/closing position of the valve is achieved through the solenoid valve being powered or de-energized. The instrument air supply is used to drive the valves; typically, the air circuit can be controlled over a certain period of time. But electricity is uncontrollable. The state of the valve in the event of a power loss is usually designed based on the safe position of the valve within the process.
For double-acting actuators, to return to a safe position in the event of a failure, a gas reservoir and one or more pneumatically controlled valves (retention valves) are required.
If it is a pneumatic ball valve, a manual switching device can be added to the pneumatic valve, allowing manual operation of the switch in the event of a loss of air or power supply
Manual operation on-site is unreliable and may not be timely; its use is not recommended.