The airlock valve is used to keep the operating air inside the actuator chamber so that when there is any defect in the air source in the air process control line, there is no disturbance in the opening of the valve. An airlock is shown in the figure.
Whether the valve is set for direct or reverse operation is determined by maintaining the position even in the event of air failure to maintain process safety by opening or closing the control valve. Air valve airlock is used when it is necessary to keep the air pressure to the actuator at the same pressure automatically. When the power supply pressure drops to less than the preset value, the air lock relay automatically locks the air pipes between the device and the control valve, causing the control valve to maintain its position until the air failure is rectified. Slowly
The principle of work
To understand the principle of work, the Airlock valve diagram is shown below:
The air pressure signal enters the upper diaphragm chamber to generate force. When this force is greater than the force exerted by squeezing the adjusting spring, the upper diaphragm is pushed up, the exhaust port closes, and the air pressure signal enters the lower diaphragm chamber, affecting the lower diaphragm. . This pushes the piston down to open the valve. Thus the flow path opens between IN and OUT. If for some reason the signal air pressure drops to a level below the set pressure, the upper diaphragm is pushed down, the pressure inside the lower diaphragm is discharged from the exhaust port, and the valve is closed by a spring force. At this time, the IN and OUT lock relays are switched off. Here the adjusted pressure is adjusted using the adjusting screw.
There are three types of configurations in the relay / airlock valve:
- Single or single port airlock (for single actuator)
- Double or double port airlock (for double actuator)
- Irlock three-port valve (changes the power supply in case of failure)
Single or single port airlock
Airlock valve single is a tool used in pneumatic actuators (spring return) and power cylinders to maintain their position (to stay in a stable position), in case of air failure or if the air pressure drops below the set limit. Pressure. The airlock is automatically reset to restore air pressure. Connected between positioner and actuator.
Airlock even double or dual port
Airlock Double Double is a tool used in pneumatic actuators and power cylinders to maintain its position by locking the pressure of both ports (to stay in constant condition) in case of air failure or air pressure reduction. Under pre-set pressure, the airlock is connected between the positioner and the actuator.
Irlock even three ports
When a three-port air lock relay is used, if the signal air pressure is set below the pressure for some reason, IN1 and OUT turn off and the current path between IN2 and OUT opens.
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