Calculating the Resisting Torque from an Exhaust Reducer

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Depends on the amount of leakage, through out the system.

You can use a needle valve & have very good control [ see above ]

Mechanically/electrically control the needle for small actuators, or ball or globe valve for larger size units to improve speed control. However, to answer the original question, the restrictor could readily slow the retraction time to months.

Does it need to be "calculated"? Maybe not:

To slow it down during retraction, fit a needle valve in the exhaust line at the solenoid valve and adjust it until the retracting speed is acceptable.

To speed it up during retraction, fit a quick-release valve at the actuator.

To slow it down both ways, fit the needle valve in the supply line from the solenoid valve to the actuator.

To speed it up both ways, fit an air reservoir at the actuator, move the solenoid valve down there downstream of the reservoir and fit the aforementioned quick-release valve at the actuator.

Anything more elaborate requires a change to the style of the system; perhaps a valve with positioning feedback and analog control of the air signal pressure to the actuator?

Sounds like a merry afternoon twiddling with things. Good luck!

These exhaust reducers use a screw to control or limit air exhausting out of the pneumatic actuator. In a way they are infinitely adjustable. What is in the pipeline? Are you trying to prevent water hammer in the system from the valve closing too quickly? A lot depends on what decree of control you need in this valve closing. A local actuation shop should be able to give you a bleed rate of these exhaust reducers.

We set ours up by trial and error. It took about twenty minutes to set the parameters. Got it close enough to program the PLC. The PLC controls the airflow via a PWM driven MOOG type valve much like the fuel injectors on your car. It works great and we can fine tune the retract speed using the load (product weight) sensor. A big plus is the system yields the same retraction speeds regardless of plant air pressure fluctuations.