Calculating flow conductance through an orifice.
Posted: Sat Oct 16, 2010 1:33 pm
This is a pretty straight question; what is the equation of molecular flow conductance through a circular orifice?
Due to convenience and availability, I am aiming to use an NW40 right angle valve as a gate valve. It has a rated flow conductance of 45l/s, which is prob good enough for my 60l/s turbo system but will, obviously, be the limiting pumping factor. However, there are other restrictions in the system so if these are all sub 45l/s then I need not worry about this valve at all.
One other smally point - my pump (Varian V60) is rated 60l/s for N2 and 45 l/s for H2. Where such valves as I am looking to use here have a manufacturer's rating of 45l/s, is that in some way for all gases, as it is just a plain orifice, or does even a plain orifice also vary according to gas type?... I'm guessing I'll see the answer to that in the answer to my question!
I've had a look but not seen anything specific to this question. I could spend a lot more time looking, but if you chaps already know the answer then I would be grateful for you jotting down the answer or directing me accordingly. In fact, a secondary question might be even more interesting for 'archival' value; what is the flow conductance through various length and diameters of bellow pipe?
thanks,
Chris MB.
Due to convenience and availability, I am aiming to use an NW40 right angle valve as a gate valve. It has a rated flow conductance of 45l/s, which is prob good enough for my 60l/s turbo system but will, obviously, be the limiting pumping factor. However, there are other restrictions in the system so if these are all sub 45l/s then I need not worry about this valve at all.
One other smally point - my pump (Varian V60) is rated 60l/s for N2 and 45 l/s for H2. Where such valves as I am looking to use here have a manufacturer's rating of 45l/s, is that in some way for all gases, as it is just a plain orifice, or does even a plain orifice also vary according to gas type?... I'm guessing I'll see the answer to that in the answer to my question!
I've had a look but not seen anything specific to this question. I could spend a lot more time looking, but if you chaps already know the answer then I would be grateful for you jotting down the answer or directing me accordingly. In fact, a secondary question might be even more interesting for 'archival' value; what is the flow conductance through various length and diameters of bellow pipe?
thanks,
Chris MB.