failure modes of pneumatic actuators = spurious valve release on fire suppressant cylinder bottle

[pdobro10]

Hi

Seeking tips on Root Cause Failure Analysis technique and failure modes (manner of failure)

Case in piont: 50+ year old pneumatic actuator that spuriously released fire suppressant from a cylinder

 

[MikeHalloran]

You probably should have replaced the whole system before it got that old.
Ask your insurance company what they would consider a reasonable design lifetime.


Mike Halloran
Pembroke Pines, FL, USA

 

[pdobro10]

Good point, and I agree. but owners believe in band-aid sustainment beyond normal business practices so they've held on until this failure raised concerns that the life safety eqpt is in fact the safety hazard.

 

[MikeHalloran]

Said owners should count themselves damn lucky that the valve didn't fail to open the cylinder when it was needed, and the triggering event didn't happen.

Or maybe such an event did happen, and the system worked exactly as designed, but your post-mortem didn't detect the triggering event.

We can't tell anything from the information given so far, but maybe your time would be better spent reviewing the design of the system, especially w.r.t. changes to applicable standards and products evolved over the past five decades.



Mike Halloran
Pembroke Pines, FL, USA

 

[gerhardl]

In industries and in countries that require certification of quality (for the complete factory), written procedures is obligatory, including rules for operational and quality check of all equipment. This will of course include all safety equipment!

Regulations and rules will vary, but a 'common sense procedure' is to check all equipment periodically, periode length according to consequence of failure.

If the factory's top management does not understand that this is one of the main tasks of a good leadership, the factory is as far as it is possible to come from proper practice of, and/or getting a certificate of quality.

Apart from this: a pneumatic actuator to operate a fire protecting device will most certainly have a failsafe operation: fail of air and/or el. or mechanical device (or any other possible position holding device) will release the cylinder action.

For the actuator itself: The most possible cause is failure over time of sealing, causing air leakage. Most common construction is air holding position, spring failsafe closing.

For solenoid valve (if any): same as above, plus el. failure.