Pneumatic emergency shut-off valve principle knowledge

Oct 18, 2019

The pneumatic emergency shut-off valve is a processing industry for chemical raw materials, and is widely used in the processing, storage and transportation of high-risk gases. It is usually operated by the control room/control center or it can be operated safely on site. Therefore, the Emergencycut-offvalve usually consists of a valve body and an actuator.

Pneumatic emergency shut-off valve working principle:

Cut-offvalve has a distinction between normally closed and normally open:

A. Normally closed pneumatic emergency shut-off valves are usually used in ammonia tanks, gas spherical tanks, and weakly corrosive gas storage tanks. The vehicle is unloaded at a long distance and the gas source switch is used to open the shut-off valve to prevent accidental injury to personnel.

Pneumatic emergency shut-off valve in the case of no air pressure, the valve flap is in the normally closed state, when the air pump inputs the pressure gas into the cylinder of the shut-off valve, the valve flap is opened. When the emergency shut-off valve needs to be closed or in case of emergency, the pressure is released. Automatically shut down. 2. The pneumatic emergency shut-off valve is fixed on the valve seat by the plunger. When the pressurized gas (compressed air, nitrogen) is injected into the cylinder through the valve seat, the valve flap leaves the valve seat. When the pressure is released, the valve flap is due to the spring force. Function, close quickly.

B, normally open pneumatic emergency shut-off valve installed in the factory production workshop pipeline, explosion-proof shut-off valve (pneumatic components) power supply and distribution control system (DCS), programmable controller (PLC) and other switching signals or leakage detection instruments, pressure control Instrument connection. When the detector finds a leak, the pressure control instrument (pressure too high/low) is energized to close, and the gas source is cut off by * time to avoid the occurrence of the situation and affect normal production. Ensure the safety of the staff.

Pneumatic actuators are divided into single-acting and double-acting types: the actuator's switching action is driven by the air source, called DOUBLEACTING. The switching action of SPRINGRETURN is only the air source drive when the opening action, and the spring action is the closing action.

Pneumaticcut-offvalve uses a pneumatic actuator. The first thing to look at is the function you need to implement. If the actuator is to be reset after a power failure, a single-acting spring-return type pneumatic actuator should be used. If the power is maintained after the power is off, then The double-acting pneumatic actuator is selected. At the same time, if equipped with a gas storage tank, it is more convenient to use a double-acting pneumatic actuator, and one cycle control can be completed after the power is cut off.