James Johnson ) writes:

Maybe he means 25 inches of vacuum, now is it inches of water or mercury (big
difference between the two)? Since atmospheric pressure at sea level is 14.7
psi there is know way he is pulling 25 psi vacuum unless he has it in a tank
pressurized to 10 psi above atmospheric.

yes, that would 25 inches of mercury. that is what is measured by the car
engine vacuum guage. if you car engine vacuum guage is 14.7 you have some
expensive engine work in your immediate future.

still the vacuum on the suction side of a vacuum pump is not limited by
atmospheric pressure, even when connected to a vacuum bag set up for resin
curing. all it means is the pump is creating a vacuum greater than
atmospheric pressure and could be run at a lower speed. imagine a vacuum
pump strong enough to suck the resin, hull, and all right into the pump.
can't do that at atmopheric prssure.


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