Bungy and Surgical tubing

[Ether]

Originally Posted by boomergeek

Ether-
For the engineering rule that the maximum of 20 inches per second for piston speed, can be ignored if the piston is moving in excess of that only when powered by surgical tubing as opposed to when the movement is caused by pneumatic pressure against the piston?

I am a complete novice at pneumatics and I'm taking an educated guess that it's the seals between the piston and the cylinder that are only rated for a maximum speed of 20 inches per second, and my guess continues that it causes excessive wear is independent of whether pneumatic force or elastic force is used to drive the piston to the excessive speed.

Can anyone with knowledge of pneumatic mechanisms explain?


Thanks!

Hi Boomergeek,

We don't know at this point that 20ips is an "engineering rule". The provenance and authority of the 20ips statement is still not known. Because of the continued debate about this, I would imagine that eventually (probably sooner than later) someone will track it down and undoubtedly post what they find.

But just assuming for the moment that it IS authoritative, we still don't know the underlying reason - seal wear? or maybe end-cap impact.

If the concern is about seal wear, my best guess would be that you are correct: it doesn't matter whether the speed is caused pneumatically or by spring load. The same applies if the concern is end-cap impact loading.


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