EKS-SP High Speed Injection Machine Eks-Sp High Speed Iinj Mach,High Speed Injection Moulding Machine,Fast Injection Mouding Machine,Servo Injection Molding Machine Ningbo Jietan Machinery Equipment Trading Co., Ltd. , https://www.jietanmachinery.com
Control valve type of choice
Selection of control valve type 1 Valve body type selection Valve body selection is the most important part of the control valve selection. There are many types of regulating valve body, commonly used through a single seat, through two-seater, angular, diaphragm, small flow, tee, eccentric rotation, butterfly, sleeve, spherical and other 10 species. Before selecting a valve, carefully analyze the medium, process conditions, and parameters of the control process, collect enough data to understand the system requirements for the regulator, and determine the type of valve to be used based on the data collected. In the specific choice, the following aspects can be considered: (1) spool shape and structure based on the selected flow characteristics and unbalanced forces and other factors to consider. (2) Wear resistance When the fluid medium is a suspension containing high concentration of abrasive particles, the valve core, the valve seat joint surface will be severely rubbed each time it is closed. Therefore, the flow of the valve should be smooth, the valve's internal material to be hard. (3) Corrosion resistance Due to the corrosive medium, try to choose a simple structure of the valve in the case of regulatory function. (4) Medium temperature, pressure When the medium temperature, high pressure and changes, should use the valve core and valve seat material by temperature, pressure changes in small valves. (5) to prevent flash and cavitation flash and cavitation only produce liquid medium. In the actual production process, flash and cavitation not only affect the calculation of flow coefficient, but also the formation of vibration and noise, so that the valve life is shorter, so the valve should be selected to prevent flash and cavitation. 2 control valve actuator selection 2.1 Output Force Consideration Regardless of the type of actuator, the output force is used to overcome the effective load (mainly refers to unbalanced and unbalanced torque plus friction, sealing force , Gravity and other related forces). Therefore, in order for the regulating valve to work normally, the matched actuator should be able to generate enough output force to overcome various resistances and ensure a high degree of sealing and valve opening. For double-acting pneumatic, hydraulic, electric actuator, there is usually no return spring. The size of the force has nothing to do with its direction of operation, so the key to choosing an actuator lies in knowing the maximum output force and the torque of the motor. For single-acting pneumatic actuators, the output force is related to the opening of the valve, and the presence of force on the regulating valve will also affect the kinematic behavior, thus requiring a force balance across the opening of the regulating valve. 2.2 Determination of the type of implementing agencies After determining the output of the implementing agencies, according to process requirements of the use of the environment, select the appropriate implementing agencies. For on-site explosion-proof requirements, pneumatic actuators should be used, and the junction box for the explosion-proof, you can not choose the electric actuator. If there is no explosion-proof requirements, the pneumatic and electric actuators can be used, but from the energy-saving aspects, should try to use electric actuators. For the hydraulic actuator, its use is not as good as the pneumatic, electric actuators a wide range, but with high precision, fast speed and smooth characteristics, therefore, in some cases, in order to achieve better regulation effect, you must use hydraulic actuator Institutions, such as power plant transparent speed control, refinery catalytic reactor temperature control and so on.