Selection of pneumatic actuators

Before selecting the pneumatic actuator, check the valve torque. And increase the safety factors on the torque, water vapor or non-lubricating liquid medium to increase the safety factors of 25%; non-lubricating slurry liquid medium to increase the safety factors of 30%.

Double acting pneumatic actuator selection example:

The choice of valve torque 210NM, air pressure is only 5bar, the medium is non-lubricating water vapor, taking into account the safety factors, an increase of 25% of the safety factors of 262NM, according to double-acting output torque table to find the gas source pressure at 5bar the corresponding torque value.

Double acting pneumatic actuators working picture:

When the air pressure from the air inlet (2) into the cylinder between the two pistons in the cavity, so that the separation of the two pistons to move the direction of the cylinder at both ends of the air chamber through the air port (4), while the two piston rack synchronization Drive the output shaft (gear) counter-clockwise. (4) into the air chamber at both ends of the cylinder, so that the two pistons to move the middle of the cylinder, the middle of the air chamber through the air port (2) discharge, while the two piston rack synchronous drive output shaft (gear ) Clockwise rotation. (If the piston is installed in the opposite direction, the output shaft becomes  rotation)

Pneumatic actuator performance characteristics are:

1, pneumatic device rated output force or torque should be consistent with the provisions of GB / T12222 and GB / T12223 above the film-type actuator;

2, Without loading situation, the cylinder input pressure required by the law, its action should be smooth, no jamming and creeping phenomenon;

3, When the air pressure in the 0.6MPa, the pneumatic device to open and close the output torque or thrust in both directions, the value should be not less than the pneumatic device signs marked with the value, and the action should be flexible, does not allow permanent deformation of the parts and Other anomalies;

4, The seal test with the maximum working pressure of the test, from their back pressure side of the air leakage is not allowed to exceed (3 +0.15 D) cm3 / min (standard state); from the cover, the output shaft leakage Air volume is not allowed to exceed (3 + 0.15d) cm3 / min;

5, The strength test with 1.5 times the maximum working pressure to test, to maintain the test pressure 3min, the cylinder end cover and static sealing parts are not allowed to leak and structural deformation;

6, The number of action life, pneumatic devices to simulate the action of pneumatic valves, in both directions to maintain the output torque or thrust capacity of the case, the opening and closing operation of the opening and closing times should be not less than 50,000 times (open - closed cycle);

7, With a buffer mechanism of the pneumatic device, when the piston movement to the stroke end position, does not allow the phenomenon of impact;

Valve torque required to determine the opening and closing of the electric actuator to choose how much the output torque, the general proposed by the user or the valve manufacturers own matching, as the actuator manufacturer is only responsible for the output torque of the actuator, the valve normally open and close required Of the torque by the valve caliber size, working pressure and other factors, but the valve manufacturers processing accuracy, the assembly process is different, so different manufacturers with the specifications of the valve torque required is also different, even with the same valve manufacturers produce the same Specifications Valve torque is also different, when the selection of the actuator torque is too small to select can not normally open and close the valve, so the pneumatic actuator must choose a reasonable torque range.

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