FLOWX Engineer 86-21-54150349
The implementation of this article is designed to help customers to select top pneumatic actuators. The actuator mounting to the valve before must take the following factors into consideration. First, safety coefficient or running torque of the valve with the manufacturers recommended according to operating conditions. Second, perform air pressure or voltage supply mechanism. Third, actuator type or spring reset and a source of the output torque and rated voltage output torque. Fifth, perform steering mechanism and failure mode (open or failure fault off). The correct choice of top pneumatic actuators is very important, such as if an actuator is too large; the valve stem of top electric actuators may be affected by the force. Instead, such actuator is too small, so the side can't produce enough torque to valve operation. Generally speaking, I think that the metal parts of top pneumatic actuators are required to operate a valve torque from the valve (such as the ball core, the valve flap) and seals (seat) of friction between. According to valve applications, the use of temperature, operating frequency, pipeline and pressure difference, flow medium (lubrication, dry, mud), many factors affect the operating torque of top pneumatic actuators. The article is going to introduce how different parts of top pneumatic actuators work.
According to the structure principle of top pneumatic actuators, ball valve basically is a polishing ball core (including channel) encapsulated in two seats (upstream and downstream). It is center of rotation on the fluid to intercept or through the ball core. The upstream and downstream pressure generated force makes the ball close to the downstream seat (floating ball structure). Valve operation in this torque case is composed of a ball with the valve seat, stem and packing friction between the decisions.
The second part of top pneumatic actuators is butterfly valve. The structure principle of butterfly valve is basically fixed on the axis according to the butterfly plate. Completely sealed in the closed position the butterfly plate and valve seat, the butterfly plate rotation (around the stem) and fluid flow in parallel, the valve is in the fully open position. On the contrary when the butterfly plate and the fluid flow are vertical, the valve is in the closed position. Operating the valve torque is determined by the friction between the butterfly plate and the valve seat, stem and packing of the institute, and pressure on the disc force also affects the operating torque as the valve is closed when the maximum torque will decrease.
Structure and principle of pneumatic actuators is basically built according to seal in the tapered plug body. There is a passage in the direction of the plug. With the plug is screwed into the valve seat, the top pneumatic actuators achieve the opening and closing of the valve. The operating torque is usually not affected by the pressure of the fluid, but is determined by the friction between open and closed valve and plug in the process. The maximum torque is in the closed. Because of the influence of the pressure, the rest of the operation always maintains high torque.