Pneumatic valve is an actuator that uses compressed air to drive and operate the valve. Its opening and closing speed is relatively fast. It is often used for quick two-position cut-off, and can also be used to adjust flow. Because it mainly relies on air source to perform operation, In flammable and explosive situations, it has high practicability and can be used to control gas, liquid, oil, and various corrosive media. The accessories in the pneumatic valve are varied, and with different accessories, they can not achieve a variety of different control methods. Users can configure the valve according to the different work needs of the valve.
The matching function of pneumatic valve accessories
1. Pneumatic triple parts are the most common accessories in pneumatic valves, and their functions can be simply summarized as: filtration + decompression + oil mist. Among them, the pressure reducing valve is a necessary accessory. No matter what kind of function the pneumatic valve must be equipped, its function is to give the pneumatic valve a standard pressure of the power air source, and the standard value is 0.4-0.7MPa.
The pressure reducing valve is a valve that reduces the inlet pressure to a certain required outlet pressure through adjustment, and relies on the energy of the medium itself to keep the outlet pressure automatically stable.
a. The function of the two-piece (filter, pressure reducing valve): to complete the filtering and pressure reducing functions of the compressed instrument air
b. Function of triple parts (filter, pressure reducing valve, lubricator): complete the filtering and pressure reducing functions of compressed instrument air, and lubricate the air.
2. Pneumatic solenoid valve can also be called directional control valve. For two-position valves that only need to open and close, solenoid valve is a necessary configuration. The solenoid valve can control the opening/closing of pneumatic valves through excitation/demagnetization. Solenoid valves are often used for on-off valves, and control the on-off of the air source gas circuit through a voltage signal to control the on-off of the valve. Definition: A valve that uses an electromagnet to control the movement of the spool, generally by controlling the movement of the pneumatic actuator to open and close the valve.
3. The valve limit switch, also known as the travel switch, can also be called the echo device. It is a field instrument for detecting valve status in the automatic control system. It is used to output the open or closed position of the valve as a switch value (contact) signal, which is accepted by the program controller or the computer searches for sampling, and executes the next program after confirmation. The product can also be used as an important valve interlock protection and remote alarm indication in the system. If you want to grasp the valve position status of the two-position valve, the valve limit switch is an effective configuration, which is an electrical switch used to indicate and feedback the movement limit position of the mechanical equipment.
4. Valve positioner, it is a necessary configuration of pneumatic control valve. The valve positioner can control the position of the valve at any opening. It takes the valve stem displacement signal as the input feedback measurement signal and the controller output signal as the setting. When there is a deviation between the two, the output signal to the actuator is changed to make the actuator act, and a one-to-one correspondence between the valve stem displacement times and the output signal of the controller is established.
Note: If it is a control valve with safe condition control, a solenoid valve must also be configured, and the solenoid valve is used to force the control valve to be in a safe valve position in an unexpected situation.
For the large-capacity cylinder valve, in order to speed up the valve action, the pilot valve must also be configured. The function of the pilot valve is to drive the pilot valve to switch the pipeline with a small amount of air to switch the pipeline of the large amount of air, so that the cylinder valve has a relatively high capacity. There are many types of pilot valves for fast charging/deflating air paths, which should be selected according to the specific needs of pneumatic valves. If the valve position to be mastered is a regulating valve, a valve opening transmitter must be installed, which can feedback the valve opening signal at any position. Due to the needs of the equipment process, the valve may be normally opened, slowly closed, or slowly opened and normally closed, then a pneumatic damper needs to be configured. The damper is to control the size of the air flow, and adjust to achieve the required valve action speed.