Faster Vacuum, multiple pumps

[marctech]

Anyone had success with using multiple pumps for dealing with shorter pot-life resins?

I have a pretty decent dual-stage robinar 1hp vacuum pump (8cfm) which is pretty quick for my 5gal chamber but it is painfully slow for my 15gal (which i put entire molds into).

When vacuuming the whole mold i suppose i don't need to get to -29inHg, i really just need to get past 25, quickly, so i can lift the cover and pour more resin, etc.

I suppose there are other practical considerations, my current pump is 9A which means i have at most another 6A pump on the same circuit. I could use another circuit if it was necessary.

Is this whole idea silly? Should i bother getting another dual-stage? Single is cheaper and has higher cfm/$ but lower ultimate vacuum strength. Do i need to get a similarly sized pump or will anything i get be additive?

[mangozac]

The only potential problem I can see is that the pump speeds won't be closely matched and this could cause more stress on one of the pumps. I'd be inclined to just find a single, suitably sized pump.

[Fleafa]

I think you'll just get a tug of war between them.

[marctech]

It does appear to work, though it makes the most difference once a strong vacuum is being pulled.

The speed from 0-25inHg is maybe 15% faster, but the speed after that seems to be improved quite a bit.

I'll measure the time to various pressures and in various chambers to paint a more complete picture.

The gain is not strictly additive, there is significant loss as I assumed possible.