The torque characteristics analysis of all kinds of pneumatic valve

pneumatic valve electric actuator are important actuators in the industrial automation control system, with the development of microelectronics technology and sensor technology, its intelligent level enhances unceasingly. Through installing additional sensors in the pneumatic valve body, by the continuous monitoring system in the operation of the microprocessor in operation parameters, makes the pneumatic valve electric actuator since diagnosis possible. Fault diagnosis is dependent on the information acquisition, for pneumatic valve electric actuator, the information such as torque is important basis of fault judging.
brake pneumatic valve in the closed and open, the torque characteristics of a special. When pneumatic valve closing, disc by fluid pressure increasing, when the gate wedge into the pneumatic valve seat, disc and the friction between the pneumatic valve seat to soar and fluid pressure form resultant force, make the required torque increasing until the pneumatic valve is closed. When the pneumatic valve opens, fluid pressure helps to pneumatic valve open, pneumatic valve motor output torque decreases. In the process of part open to fully open, the torque is mainly by the friction between the worm screw and packing on the friction of torque is relatively stable. If the sealing filler of the pneumatic seat performance degradation, torque characteristic curve will be a slight concussion near the closed area. If the base of the pneumatic valve wear deformation or deterioration of lubrication condition, then close the pneumatic valve required torque increase obviously.
main factors affecting the pneumatic ball valve torque with the friction between the worm gear and worm, O ring, pneumatic valve stem seal friction and closed or open in the process of the spherical sealing element on the base of friction, etc. The friction between the worm gear and worm is usually constant value, because in the trip, it is a sphere in the pneumatic friction on the seat, but in the process of closing and opening, the sphere in the pneumatic friction significantly increased on the seat, this is because under the action of fluid pressure, prompting a sphere and pneumatic seat together, provide the seal. If a sphere or pneumatic seat have scratches or dents, shut down the required torque will be increased.
butterfly pneumatic valve torque of the main bearing friction, pneumatic valve stem seal friction ( General is a constant value, pneumatic seat sealing packing friction and fluid pressure of butterfly plate in the process of running. Because of the pneumatic valve butterfly butterfly plate in the middle of the liquid flow, the effect of fluid pressure is more obvious. When the butterfly pneumatic valve of the whole trip transfer torque increases, bearing the problem. If the pneumatic seat or the body is damaged, pneumatic valve is closed and open when the torque is abnormal. Fluid flow velocity, viscosity and temperature changes will affect the schedule of dynamic torque, the torque change does not mean the pneumatic valve itself has a problem.
can be seen from the analysis of characteristics of all kinds of pneumatic valve torque, each torque characteristic curve corresponds to the corresponding fault types, by monitoring the torque characteristic curve, we can determine not only the common electrical failure, pneumatic valve motor itself and can diagnose mechanical structure of the pneumatic valve actuator injury, lubrication condition and state of packing, aspects of pneumatic valve electric actuator working condition to provide the overall assessment.