How quickly does air return to a vacuum chamber?

Question

I know there are a lot of variables that affect how quickly this would occur. Any information on the topic would be highly appreciated. For sake of argument, lets say 1 square foot chamber, lets say medium vacuum, and a 1/16 square inch opening. If you could provide me with any formulas or thoughts on the topic that would be very helpful.

Also, how would the speed change with a different gas, say hydrogen? Or even, a liquid such as water?

Thanks

Maybe I don't understand, but can you explain the relevance? — Ryan Sinclair, Mar 27 '14 at 04:44
A chamber with a vacuum in it would have a volume, not an area - 1 cubic foot. Why don't you state your pressure, say 1/10 atm. Is your opening round or square? — LDC3, Mar 27 '14 at 03:33
LDC3 - yeah mistake on area/volume. Square opening and it would be 1/100 (.01) atm. Thanks — Ryan Sinclair, Mar 27 '14 at 23:12
Martin, can you explain how I can apply that thread to a situation with a vacuum? — Ryan Sinclair, Mar 27 '14 at 23:17
The pressure difference is just 1 atm in the case of vacuum and depends on the height of the water in the other case — Martin Beckett, Mar 28 '14 at 08:06

score 2 · Accepted Answer · answered Mar 27 '14 at 20:30

2

I depends on the pressure ratio between the chamber and ambient . As long as the ratio is critical, the ambient air will flow through the orifice at the speed of sound (with respect to the state in the chamber). For undercritical pressure ratio the flow can basically be found by the Bernoulli Equation.

answered Mar 27 '14 at 20:30

Mirc Breitschuh

307

How would I know if it were critical? I'm assuming that under most circumstances it would not be critical. – Ryan Sinclair Mar 27 '14 at 23:13
A short introduction is given for example here http://www.thermopedia.com/content/267/?tid=104&sn=1297 – Mirc Breitschuh Mar 28 '14 at 09:38

How quickly does air return to a vacuum chamber?

1 Answers1