Lock Up Valve, YT-400 sense the main supply pressure and shuts down the air flow when the pressure is lower than setting.
The lock-up valve detects the plant's main pneumatic pressure as a signal pressure, and when the signal pressure drops below the set pressure, it blocks the flow path inside the lock-up valve to completely block the flow of pneumatic pressure. For general use, it is installed on the control valve, and when the main pneumatic pressure from the plant compressor is lower than the required pressure due to power failure or pipe breakage. It basically senses and blocks the flow path between the actuator and the positioner to maintain the current valve opening.
