Choked regulating valve
Choked regulating valve
(OP)
Hi,
I'm sizing a pneumatic test stand for the testing of aeronautical components. I have the need to use pressure regulating valves.
There is a concept i still don't understand and i would appreciate your help.
I have a P1 pressure of 30 bar and a flow of let's say 50 Kg/min.
I need to have a P2 pressure of 3.5 bar or 5 bar, for the same flow.
In this conditions a pressure regulating valve will be chocked.
My question is that if a can control the P2 pressure, the confusion is that for both conditions i have the same Kv.
Regards,
Fábio Silva
I'm sizing a pneumatic test stand for the testing of aeronautical components. I have the need to use pressure regulating valves.
There is a concept i still don't understand and i would appreciate your help.
I have a P1 pressure of 30 bar and a flow of let's say 50 Kg/min.
I need to have a P2 pressure of 3.5 bar or 5 bar, for the same flow.
In this conditions a pressure regulating valve will be chocked.
My question is that if a can control the P2 pressure, the confusion is that for both conditions i have the same Kv.
Regards,
Fábio Silva





RE: Choked regulating valve
If you don't change anything, to get a lower pressure with your main control valve means you will have less flow and hence a different Kv.
If you draw out your system and post it, it might become clearer what you are doing.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve
I've attached the test requirements and the diagram of the test facility
http://files.engineering.com/getfile.aspx?folder=1...
http://files.engineering.com/getfile.aspx?folder=e...
RE: Choked regulating valve
RE: Choked regulating valve
I'm not actually sure this is going to work as shown. E.g. your spread sheet shows test 1 and test 4 with same p2 pressure, but different flow rates (one double the other). This will simply not be possible to achieve with a single control valve. To do this sort of thing you might need two or three different control valves to mix and match OR have some sort of additional control valve downstream the equipment to be tested to create a variable back pressure (p2) which then needs to be varied along with the primary valve which could be used to vary mass flow or keep mass flow the same. Other than test 6, all your P2 pressures appear to be in the choked flow region so mass flow should stay the same if you don't change the valve opening. There is quite a large range of mass flow here so one valve might not be able to do this entire range with any accuracy.
As it stands, you could vary pressure and flow at the same time, but couldn't keep one constant and change the other.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve
RE: Choked regulating valve
RE: Choked regulating valve
This implies some sort of control over flow or pressure within the equipment under test which isn't visible and I'm not sure you've quite got this, but I could be wrong.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve
RE: Choked regulating valve
Your turbine in effect has a flow pressure curve associated with it, the key word being curve, not flat line....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve
RE: Choked regulating valve
To get one valve to provide this range of pressures and flows is not feasible, especially with differing equipment.
I would go for at least three different sized valves in parallel to even get close to your range of pressures and flows.
That's also a fairly significant sized heater for a "test" rig (max 216 kW). I'd love to see a picture of how big this is - I'm thinking about the size of a small hangar....
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve
RE: Choked regulating valve
http://www.schubert-salzer.com/en/download-cs/soft...
It's fort a type of valve with a 40:1 rangebility in Kv
RE: Choked regulating valve
Using software like you have is all well and good to get you an idea, but you really need to talk to a few vendors to get some advise on what is actually practical.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Choked regulating valve