Pneumatic Valves - Open Center/Closed center??

JesperMP · Oct 31, 2018

If after venting compressed air energy, there is a risk of movement or dropping because the pneumatic energy isnt holding things in place, there must be manually inserted safety pins or jigs, or automatically actuating clamps/brakes integrated into the cylinder.
However, for the integrated clamps I have seen that such clamps are not accepted in certain industries, but I dont know the exact reasoning.

Timeismoney08 · Oct 31, 2018

Thanks for the feedback.

I guess where I was confused, was if I remove the air via an air dump, the potential for harm is still there if something were to fall or move. So I wasn't sure if by dumping the air, did I also need to assure the valves were locked in place with the same regard. I guess the simple answer is "of course".

Thanks for the clarification.

JesperMP · Oct 31, 2018

It is not the valves that must be locked in place.
It is the mechanical parts that could start to move that should be locked in place.

GaryS · Oct 31, 2018

I see some of you are concerned about dumping the air on both sides of the cylinder
An option would be to revere the action of the solenoids energize to vent pressure o both sides with solenoids off. this would give you the results you are looking for.

wes.s · Oct 31, 2018

The proper spool with a double pilot check valve will stop a cylinder mid stroke.

Example.
https://www.aladco.com/dual-check-pneumatic-check-valve/

roxusa · Nov 1, 2018

I have an application like this that vents both sides for ZES but like Seth350 points out once the device is enabled it will slam back into position. The OEM requires you to push back by hand if out of home position before energizing to prevent this. Thoe no operators do and it takes quite a beating.

jstolaruk · Nov 1, 2018

JesperMP said:
However, for the integrated clamps I have seen that such clamps are not accepted in certain industries, but I dont know the exact reasoning.

True, Ford and GM are now telling us that rod-locks are no longer considered adequate for safe stopping; citing rod-lock wear as one reason. If the cylinder is actuating a slide, a safety rated slide clamp is required. And without some kind of safe clamping to inhibit motion, the mechanical designer has to go back to the drawing board.

Pneumatic Valves - Open Center/Closed center??

JesperMP

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