Vacuum pump CFM

[Acrisoft]

May some of you guys comment which CFM capacity vacuum pump you use and what this pump is able or not able to do. For e.g. is a 5CFM pump enough for most of commercial systems ?
If a guy buy a 3.5CFM pump what will be his limitations ?

[Brian_UK]

Here's some calculations to help (or hinder) your thoughts.

http://www.vtechonline.com/pdf/Sizing_Vacuum_Pumps.pdf

[Magoo]

Hi
vac pumps are rated on free air capacity, that is with nothing attached to it, at atmospheric pressures, add service gauges and hoses the flow rate drops dramatically. A 5 cfm pump is well suited for commercial work

[charlie patt]

i always prefer a large cfm pump twin stage at least 6cfm on commercial systems but to get the best a torr gauge and 4 line gauges are a advantage and change the vac pump oil on a regular basis it really depends on what you are doing with it/ install? repair if it has moisture the bigger the suc the better it will get in my book