Power is required to operate the machine. Part of it is external fuel, and the other part is powered by energy conversion. A valve on a machine is the tool that uses this energy conversion to operate the machine. Pneumatic valve is a device that uses compressed air to drive machinery, and its principle is very delicate.

The pneumatic flow valve in the cylinder accessories is the pneumatic control element in the pneumatic system. The correct selection of the control valve is an important part of the pneumatic system design. A reasonable selection can simplify the circuit, reduce the type and quantity, reduce the consumption of compressed air, and reduce the cost. Improve system reliability.

 

 

Pneumatic flow valve refers to the air source as the power, the cylinder as the actuator, and the 4 ~ 20 mA signal as the driving signal, through the electric valve positioner, converter, solenoid valve, guard valve and other accessories to drive the valve, the pneumatic flow valve has It has the advantages of simple control, fast response, and intrinsic safety. In the case of strong flammability and explosion, no further explosion-proof measures are required. Pneumatic flow valve is generally composed of pneumatic actuator and regulating valve connection, installation and debugging. Pneumatic actuator can be divided into single-acting and double-acting. There is a return spring in the single-acting machine, and there is no return spring in the double-acting machine. Among them, single-acting actuators can automatically return to the open or closed state of the valve's initial setting in the event of a loss or failure of the air source.

Pneumatic flow valve has two types of air separation type and air closed type according to the movement form: the so-called no type and NC type, the air opening or air closing of the pneumatic control valve, generally through the positive and negative effects of the actuator and the different assembly methods of the valve structure to fulfill.

The structure of pneumatic flow valve

Pneumatic flow valve is mainly composed of pneumatic actuator, valve body and accessories. The actuator is powered by clean compressed air, receives 4~20 mA signal or 20~100KPa gas signal, drives the valve movement, changes the flow area between the valve core and the valve, and plays the role of regulating flow. In order to improve the linearity of the valve and overcome the influence of the friction of the valve stem and the change of the adjustment medium conditions (temperature, pressure), the valve positioner is used together with the adjustment valve, so that the valve position can be accurately positioned according to the adjustment signal.

The actuator is composed of diaphragm/piston, spring, handwheel, pneumatic rod, coupling and other main components. For the safe operation of the machine, some important valves are designed with solenoid valves, guard valves, quick relief valves and other accessories to ensure the safety of the machine. The regulating valve realizes quick opening (closing) or guarding function (three-level self-locking protection function) in the event of loss, signal loss or gas loss to meet the safe operation requirements of the process system.

The three-level protection of the regulating valve: energy saving protection, power-off protection and signal source cut-off protection.