Pneumatic valve accessories collocation function and principle
Pneumatic valve is a kind of have the aid of compressed air to drive the operation of valve actuators, the opening and closing speed is relatively fast, two used to quickly cut off to use, can also be used to adjust flow is used, because its mainly depends on gas source to perform operations, gu in inflammable and explosive occasions, has high practicability, can be used to control gas, liquid, oil, and all kinds of corrosive medium.And pneumatic valve accessories change, with different accessories, can not reach a variety of different control mode, users can according to the different work needs of the valve, to the corresponding configuration.
1, pneumatic triplex is the most common accessory in pneumatic valve, its role can be summarized as: filtration + decompression + oil mist.One of the pressure relief valve is a necessary accessory, no matter what kind of function of the pneumatic valve must be configured, its role is to give the pneumatic valve a standard power air source pressure, the standard value is 0.4-0.7mpa.
Pressure reducing valve is through regulation, will import pressure to a need to export pressure, and rely on the energy of the medium itself, so that the export pressure automatically maintain stability of the valve.
A. Function of the two parts (filter, pressure reducing valve) : to complete the filtration and decompression function of the compressed air in the instrument
B. Functions of triplets (filter, pressure reducing valve, oil mist) : complete the air filtration and pressure reduction function of the compression instrument, and lubricate the air.
2, pneumatic solenoid valve, also known as directional control valve, for only need to open and close two valves, solenoid valve is necessary configuration, solenoid valve through excitation/degaussing to achieve the control of pneumatic valve on/off.Solenoid valve is often used to switch valves, through the voltage signal control air source air circuit on and off, to control the valve switch.Definition: the valve with the moving spool controlled by an electromagnet is generally realized by controlling the movement process of pneumatic actuator to open and close the valve.
3, valve limit switch, also known as travel switch, can also be called reply.It is a kind of field instrument for detecting valve state in automatic control system, which is used to output the open or closed position of the valve with the signal of switching quantity (contact), which is accepted by the program controller or sampled by the computer. After confirmation, the next procedure is executed.The product can also be used for interlock protection and remote alarm indication of important valves in the system.The valve limit switch is an effective configuration to indicate and feedback the movement limit position of the mechanical equipment if the valve position of the two-valve is to be mastered.
4, valve positioner, it is the necessary configuration, pneumatic control valve can be controlled by the valve positioner of the opening of the valve in any position, it will stem the displacement feedback signal as the input signals, as set in the controller output signal, comparing, when there is deviation, change of its output signal to the actuator, the actuator movement, the valve stem is established between the displacement of The Times and the controller output signal
One to one correspondence.
Note: : if there is a safe condition control valve must also be equipped with solenoid valve, through the solenoid valve to force the control valve in the safe valve position under unexpected circumstances.
For large capacity of the cylinder valve, in order to speed up the action of the valve, pilot valve is also must be configured, the role of the pilot valve is driven by a small volume of gas signal to pilot valve to switch large gas pipe line, make the cylinder valve has fast charge/discharge gas gas path, there are many types of pilot valve type, it is optional according to the specific needs of pneumatic valve.
If the valve position to be controlled is the regulator, the valve opening transmitter must be installed, which can feedback the valve opening signal at any position.Due to the requirements of equipment technology, the valve may be normally open, slowly close, or slowly open, normally close, so it needs to be equipped with pneumatic damper, damper is to control the size of air volume through, through adjustment to achieve the required valve action speed.
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