Vacuum Pump Sizing – Evacuating A Chamber

We’ve previously talked about some of the tools we’ve made available to help select the right vacuum pump for your work.  Our pump selection guide is a great choice if you have a strong sense of your operating parameters.  And for drying processes, we’ve put together tools that help estimate the process time or pumping speed (flow rate) required.

Another common application for vacuum pumps is to simply pump down a chamber in order to establish a vacuum level, where there are no vapors being generated.  This process sounds like a relatively simple calculation would be sufficient – where the flow rate would simply equal the volume that needs to be pumped out divided by time.

But it turns out that, because the volume of gas varies with pressure, the math is a little more complicated.  It turns out you have to modify the flow rate = volume/time equation by multiplying by the natural log of the pressure ratio.  To help, we have developed a new calculator intended to help estimate the pumping speed needed to evacuate a vacuum chamber.  Based on the volume of the vessel that is to be evacuated, the desired pump down time, and the vacuum level you want to get down to, it will calculate the pumping speed required.  If you know the leakage rate of your system, you can also factor that in.

Or you can always email us to get help in sizing a pump.