Sounds like the piston ratio thing I was talking about can be a huge variable depending on the application?
For debate sake.....
Any thoughts if say .....you were to build a chamber sealing piston valve with a 2" seal on the chamber but a 4" diameter piston on the exhaust side?
Pro's / cons?
Where I see the problem in "choking" is in co-axial and barrel sealing piston valves.
The squared edge pipe was the problem the oil guys were dealing with.
What I don't know is at what flows and pressures the choking begins. Like I said, I got my info from the deep well drilling.
I think Freefall commented on the phenomenon of "choking". I can't remember if he said we got to those pressures and volumes spudding or not.
I learned about QEV valves in 1996 during an unintended on the job training SNAFU.
Marine weather had rotted out the old one and the company no longer existed.
We needed to replace a valve that would release pressure and volume on an adjustable dial in range from 2 PSI to about 80 psi.
It worked really cool:
You dial in 2-80 psi on a regulator and when the hand valve was activated it would dump at 2-80psi, whatever you set the psi....no more or less. If you then dialed the pressure down...the valve leaked off to the new pressure setting.
The idea was to pressurize a long clamp with a moving track.
Replacing valves long extinct and not being a pneumatics engineer, I ordered and installed a 2" QEV valve that worked like this:
You preset the activation pressure to 2-80 psi on a regulator and when that pressure was reached the valve would dump all the air at full system pressure!
The valve was connected to 5ea, 12" dia air cans that pushed down a track used to grip large power cable and push or pull it.
In action, the unit honked like a sprinkler but sounded like the T-Rex in Jurassic Park...the unit was alive and insane as we had no control over it!
It was kinda funny.
There was no taking the valve back so I disassembled it to learn it's secrets. What amazed me was how little the valve disk actually moved!
The valve that did the sealing had multiple sealing surfaces....It looked like a martian flying saucer, a frisbee or cross between an automotive exhaust valve and a spool valve. It had multiple sealing surfaces which the literature suggested guaranteed very fast opening times and little opportunity to be jammed by foreign material.
It was called an adjustable piloted QEV valve.