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bmiller

Help me with a term regarding air pressures

32 posts in this topic

You have a compressor/storage system with a working pressure of 6,000psi. It is used to fill cylinders to 4,500psi.

What is the term for the difference between 4,500 and 6,000? Reserve working, head space, differential, bacon?

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"Overhead" pressure comes to mind, but darned if I can find a cite or other relevant guidance to justify the opinion.

 

 

 

Looking around, though, got me wondering what the pressure of these puppies are set to -

 

 

1.jpg

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The differential pressure is 1500 psi...

 

in the boobs i dunno. I prefer mine more low pressure.

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

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Safety Factor

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Because it is faster? If your compressor topped out at 4500, jamming the last few pounds in will take forever. Someplace there's got to be a chart of air flow in CFM vs differential pressure between compressor output and flask.

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

Cascade system for breathers?

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

It's pressure differential.

 

You need the additional pressure for the pressure drop in the transfer process I would imagine. YMMV here as I have never worked with air pressure that high.

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ok, you actually have a few terms in play here. The additional pressure is simply the differential, aka "delta-P".

 

This applies to your tank-filling scenario because it's a factor in the flow coefficient (Cv) of the transfer.

 

Cv = Flow times the square root of (specific gravity / delta-P)

 

(sorry, I don't know how to get a square root symbol and other mathematical expressions to show up on a forum)

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A good source of this type of info is a Cameron Hydraulic Data book. Damn thing is my bible for Mechanical Engineering.

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

Cascade system for breathers?

Yep, trying to convince staff we need to replace a 35 year old machine.

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

 

Cascade system for breathers?
Yep, trying to convince staff we need to replace a 35 year old machine.
I'd call one of the big vendors and chat with a salesman. My experience is they have the process of explaining system capacity and performance nailed and will help for free (goodwill). The big points to make are reliability, historical and projected cost of maintain/repair, part availability, and on the operational side the capacity and speed to refill bottles expressed as a first alarm, second alarm etc. assignment. How many 15 to 20 minute cycles can the full assignment utilize before the incident is out of air relative to fill time of the cascade supported by the compressor.

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OK I'm using the term in this context.

 

Trying to explain why you need 6,000psi in storage to fill 4,500psi cylinders.

Cascade system for breathers?
Yep, trying to convince staff we need to replace a 35 year old machine.
I'd call one of the big vendors and chat with a salesman. My experience is they have the process of explaining system capacity and performance nailed and will help for free (goodwill). The big points to make are reliability, historical and projected cost of maintain/repair, part availability, and on the operational side the capacity and speed to refill bottles expressed as a first alarm, second alarm etc. assignment. How many 15 to 20 minute cycles can the full assignment utilize before the incident is out of air relative to fill time of the cascade supported by the compressor.

I'm actually trying to tie into a request to transition to the 5.5 operating system. The rest of it the have a pretty solid grasp on.

 

Our older Bauer says "Made in West Germany", that should give an idea how old it is.

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Made in West Germany is probably why it's still running.

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For conversation's sake, I'd refer to it as residual pressure. Technically differential is correct when discussing two different pressures, but the point you're trying to make is that it's practical to store 1500 PSI of residual pressure to facilitate faster jamming. That's how I'd express it.

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This thread is useless until our resident Cliff Clavin chimes in with his take on this.

Oh wait it did have tits, I take it back it is a good thread.

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Capacity is pressure times volume.

 

A 1 gallon tank at 6000psi does not have the capacity to fill a 5 gallon tank at 4500psi.

 

100 gallons at 6000psi is a whole other matter.

 

atoyot wins. Fantastic capacity.

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It's always nice to have a little left over even when you think you're done.

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