Conductance, gas flow and pressure question

[leoflc]

Hi there,

I have been doing some research about vacuum system setup and I've seen the setup shown in the attachment.

Pressure: P1a, P1b, P2a, P2b
Throughput/gas flow: Q1, Qs
Pump speed: Sp (pumping speed of the pump)
Conductance:Ca, Cb, C

Some papers have assumed that P2a = P2b, but it seems to me that will only work if Ca = Cb = 0.

If Ca and Cb exist:
P2a=(Q1+Qs)/Sa
1/Sa=(C+Ca)+1/Sp

and

P2b=(Q1+Qs)/Sb
1/Sb=1/(C+Cb)+1/Sp

So to make P2a = P2b, Ca = 1 - Cb.

Is that right? Or am I missing something?

Thank you very much!

 

[eljose79]

Hi there,

Thank you for your question. Your calculations are correct. In order for P2a and P2b to be equal, the conductance values Ca and Cb must be equal to each other. This is because the conductance represents the ease with which gas can flow through a certain pathway. If Ca and Cb are not equal, then the gas flow will differ and P2a and P2b will not be equal. It is important to consider all factors, including conductance, when setting up a vacuum system to ensure accurate and consistent results. Keep up the good work with your research!