Marc Wiese wrote:

The 1996 corvette GM 12v electric motor driven air pump I have weighs
just 2 lbs, 4 oz. I have no idea what amount of air it will supply

yet.

Marc Wiese

snips..

Also, what exactly are the airflow requirements for the vacuum system in
an airplane?

I've wondered that since my electric pump pulls almost 25 pounds, if
that wouldn't overwhelm the regulator and damage the instruments.  The
only data points I have for it are the few folks who are using it and
have used it for several years without problem.  I never bothered to try
to quantify it before.

AI Nut

Depends on if you have both a directional gyro and an attitude gyro.
I don't know what either one requires in cubic feet per minute.
I do know that this smog pump  flow rate (see chart) is reported to be
more than enough.  A smog pump has far more displacement than a aircraft

vacuum

pump. I would guess about ten times as much just from looking at the size
of them. A bar is 15 psi and most AC instruments as I recall need
5 psi or about .33 bar.

Paul Lamar

Actually, it's 5 inches of mercury, and since 30 inches of Hg is approx

15 psi,

we'll call 5 inches approx 2.5 psi.

Bill Freeman

Thanks Bill. That correlates better with my estimate of ten times the
displacement of an aircraft vacuum pump.

Paul Lamar

Seems like a good reliable source of vacuum.

Too bad they are so heavy because the are WAY better built than AC
vacuum pumps.  I pulled apart and fixed the frozen one on my old
Blazer.  Lots of needle bearings and well put together.  Frozen due to
rust, but freed it up and it has run for about 10K miles with no problems.
Unfortunately the housing is cast iron.  If it was thinwall aluminum it
would start getting pretty near the wt of an "real" vac pump.

Bill Freeman

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