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In a message dated 5/19/2010 1:57:03 P.M. Pacific Daylight Time,
hc.fulton@gmail.com writes:
I am using an electric driven pump I tend to agree. A hand pump or peddle pump would be slow and very tiring
to pump that much air.
As Hugh said, it's much better to pump water that doesn't compress.
If I was going to add a pump to the inside of my sub, I think I'd go with a
piston type pump that could pump at high pressures. Now, the higher the pressure
the slower it would pump and the more electricity it would use, but it may be
needed to pump water at depth like maybe to pump out the hard VBT tank if your
HP air was depleted.
A "low pressure/high volume" air pump would be useful once the boat
reached the surface and a "snorkel tube" was able to suck in fresh air, but most
likely only suited to a fairly large boat where lots of battery power, air
ducting, and room for the required equipment existed.
On a little psub, an extra scuba tank takes up little space, uses no
electrical energy, has no moving parts, and can be refilled for 4 bucks. Pretty
simple insurance to have an extra one on-board. And it is charged at 2400 psi so
using it at depth is possible.
Frank D.
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