To explore the pneumatic - valve type how to choose

Pneumatic control valve from fluid mechanics point of view, pneumatic control valve is a throttling element of local resistance to change. For incompressible fluids, flow only change with drag coefficient. Pneumatic control valve of the change of drag coefficient is achieved by changing the stroke of valve core. General pneumatic control valve and actuator work together. Such as pneumatic control valve and actuator combined into a whole, is a pneumatic actuator, is the most widely used in modern industrial control system is a kind of actuators. Pneumatic - valve to match the electric actuators, and can be used as a control system of the various actuators ( See pneumatic actuators, electric actuators) 。 Pneumatic control valve of pneumatic control valve and classification is also called the control valve, is the main type of actuator, by accepting conditioning control unit of the output control signal, from engine operation to change fluid flow. Pneumatic valve and valve general, the executing agency. If by their ticket enforcement agencies use the power, pneumatic control valve can be divided into pneumatic, electrical, fluid movement three, namely to compressed air to power sources pneumatic pneumatic control valve, based on electric power sources of electric pneumatic regulator, as a liquid medium ( Such as oil, etc. ) Pressure as the power of electric hydraulic pneumatic control valve, in addition, according to its function and feature points, and electromagnetic valves, electronic style, smart, on-site total linear pneumatic control valve, etc. Pneumatic - valve structure types of products is also varied, but also in constant updates and changes. In general valve is common, can match with pneumatic operation organ, also can match with electric actuators or other actuators. Pneumatic - valve type selection of pneumatic control valve body is a lot of more phyletic, commonly used is through single-seat, pass-through two-seater, angular, diaphragm, small flow rate, tee, eccentric rotating, butterfly, sleeve, spherical, etc. 10. Before you choose the valve, the control process of medium, the careful analysis of process conditions and parameters, collect enough data to understand the system requirements for pneumatic control valve, according to the collected data to determine the valve type to be used. In specific choices, can consider from the following aspects: ( 1) Mainly based on the selected valve core shape of flow characteristic and factors such as unbalanced force. ( 2) Wear resistance when fluid medium is suspending liquid containing high concentrations of wear particles, the valve core and valve seat joint friction surface every time shut down severely. So the valve flow to smooth, internal material is hard. ( 3) Corrosion resistance due to the corrosive medium, in the case of can satisfy regulating function, try to choose structure simple valves. ( 4) Medium temperature, pressure, when the medium temperature, high pressure and large, should choose the valve core and valve seat materials by temperature, pressure changes small valves. ( 5) Prevent flash flash and cavitation and cavitation produced only in a liquid medium. In the process of practical production, flash and cavitation effect not only the calculation of flow coefficient, still can form the vibration and noise, make the valve life is short, so when choosing the valve should prevent the valve from flash and cavitation. Pneumatic control valve actuator consider 1 output force actuator regardless of type, the output power is used to overcome the effective of load ( Mainly refers to the unbalanced force and unbalanced torque and friction, the role of the sealing force, gravity and related force) 。 Therefore, in order to make the pneumatic - valve to work properly, with the implementation of the mechanism to produce enough output force to overcome all kinds of resistance, ensure high seal and valve opening. For double-acting pneumatic, hydraulic, electric actuators, are generally not reset spring. The size of the force has nothing to do with its direction, therefore, the selection of the actuator is the key to find out the biggest output force and rotational torque of the motor. For single acting pneumatic actuators, the output power is associated with the opening of the valve, pneumatic control valve on the emergence of the force will also affect the movement characteristics, therefore needs to be established in the pneumatic - valve opening range force balance. 2 determine the type of actuator on the actuator output force is determined, according to the process using the environment requirements, choose the corresponding actuator. For the scene with explosion-proof requirements, should choose pneumatic actuators, and junction box for explosion-proof type, cannot choose electric actuators. If there is no explosion-proof requirements, pneumatic, electric actuators are optional, but consider from the aspects of energy saving, should try to choose electric actuators. For hydraulic actuator, the as pneumatic, electric actuators are widely used, but have the characteristics of high precision, fast action and smooth, therefore, in some cases, in order to achieve better control effect, must choose hydraulic actuators, such as power plants transparent machine speed regulation, the refinery catalytic device reactor temperature regulation control and so on.