putting vacuum pumps in series?

[pmg804]

I was wondering if it would be OK to put two old, weak two-stage vacuum pumps in series as a replacement (supplement) for a single-quad MS.

[thohry]

I have not tried for GC/MS, but for a vacuum evaporator and it helped.

This is my post: http://chromforum.org/viewtopic.php?f=19&t=30511

[James_Ball]

Is it in series or in parallel? Not sure if in series where the second pump would be pulling on the exhaust of the first pump it would be good. With a Y connector and both pulling in parallel I think it would work ok.