On Tue, 23 Aug 2011 22:17:49 -0700 (PDT), Robert Macy
wrote:

The pumps look like perfect form factor, pricing is good, but they all
use 12Vdc
I'll check about their ability to operate against head pressure.

Numbers for pressure and flow rate would be nice. The landlubbers
version of the bilge pump is called a "Submersible Sump Pump" which is
usually used to drain flooded basements. I have one of these:
http://www.acehardware.com/product/index.jsp?productId=1272836
Works great pumping water, but not so great pumping thin sludge and
gravel.

Regardless of type, you'll need to compromise between: flow rate,
pressure, back pressure (head), and power drain. Sump and bilge pumps
are made to move volumes of water, at fairly low power drain.
Therefore, you're not going to get much pressure out of them. Worse,
if you try to lift the water too high, the flow rate will decrease
until the pump can no longer lift the head of water. If you want
plenty of pressure, but little flow rate, look into a garden pond or
fountain pump, which will launch water to quite an altitude.

Your vague specifications also included something about "liquid,
mainly water based". All the aformented are for pumping water, not
sand, rocks, gravel, sludge, sewage, etc. If you cannot filter out
the debris at the intake, you're going to need a specialized pump that
can eat rocks and not destroy itself. For that, you'll need a sludge
or slurry pump, which uses a flap valve pump mechanism instead of
gears or a vane pump. For example:
http://legacy.shurflo.com/pages/new_industrial/industrial/gen_industrial/subcategories/2088_ADP_12DVC.html
These also have the advantage of being able to run without any water.

As for noise, good luck. If you shove too much water through the pump
to quickly, the pressure behind the impeller will drop sufficiently
low for the water to literally boil. That's called cavitation and
it's a major source of noise, inefficiency, and self destruction. If
you don't want noise, you'll need to carefully match your pump to your
application. (Unlike my former neighbors mis-sized hot tub pump that
made more noise than a diesel truck up to the day that the pump
literally exploded). In general, fountain pumps are made to be rather
quiet if that's an issue.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558