regulator middle pressure

[aquageorge]

A Swidish regulator manufacturer claims that lower middle pressure (about 5 bar) is better than a pressure of about 10 because the air in the LP is less dense so that breathing effort is less. Does anyone know if that is a fact? If that is the case, why don't other manufacturers follow the same design. Is it so difficult to achieve?

 

[Stone]

I don't buy the "air density" claim. The air you breath from your second stage is delivered at ambient pressure, regardless of your IP.

 

[MikeFerrara]

In the laminar flow range (when flow has a linear relationship to presure) the flow accross a restriction (the valve) is depenant on the presure accross it and the resistance to flow in the restriction. The greater the presure the greater the flow. The interstage area also acts as a resivoir. The higher the presure the more gas is in the resivoir. There are other consideration, otherwise they would raise the presure. I do not know what the perfect value would be and it would depend on the specific design. Their statement. however sounds like pure bs to me.

 

[Ari]

Are we talking laminar flow here? I am not so sure that it behaves tshis way throughout the whole system.

Ari

 

[Rick Murchison]

Originally posted by aquageorge
A Swidish regulator manufacturer claims that lower middle pressure (about 5 bar) is better than a pressure of about 10 because the air in the LP is less dense so that breathing effort is less. Does anyone know if that is a fact? If that is the case, why don't other manufacturers follow the same design. Is it so difficult to achieve?

Could you cite the claim? As you've presented it it is pure bull.
Rick

 

[MikeFerrara]

Ari,
Yes, the statement I made refered to laminar flow. However even if flow is turbulant increased presure should mean increased flow but the increase is no longer linear. Also some geometries might result in a decrease in flow with an increase in presure. I don,t think you will find that situation in a reg at the presures we are dealing with. Been away from fluid flow for a while but I believe my statement is esentially correct.

 

[Ari]

Last time I dealt with flow issues was 1986. Didn't go there since.

I believe that some of the flow, especially aroud the second stage is turbolant, but still at the stage where higher pressure will result in higher flow speeds and flow rates.

So before we have to go back to our fluid mechnics text books, I will lay this to rest.

Ari ;-0

 

[Norm]

As the others have said, 'BS'.