Where to get: pump for recirculating liquid - need high flow rate against high back pressure

Electric bilge pump.

If you need pressure, not just flow.. a peristaltic pump will work well. This pump uses rollers to continuously compress a loop of tubing to act as piston-like motion for positive pressure flow.

Eventually the tubing loop needs to be replaced.. how often depends upon the type of tubing used.

In choosing a pump suitable for your application, you'll need a fairly acurate "guess" of the flow rate. The flow rate is related to the nozzle size, which can usually be adjusted/replaced.

-- Cheers, WB .............

You could check with Grainger. Look for a soda machine pump. These are bronze gear pumps and can be bought with a motor attached. Eric

Home Depot - garden section, submersible water pumps for fountains...

John :-#)#

call Depco pump, they'll figure something out. I had goofy request and they found the pump I needed.

Thank you for the URL.

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:

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:

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.

Is the flow rate critical? You can generate 40-60 psi head with a properly-sized centrifugal pump. But the flow might vary significantly as the back pressure builds up.

For a flatter flow characteristic, a positive displacement pump plus a pressure relief valve will give you a more constant flow right up to where the valve opens. But this is more of a specialty setup and a pump expert may need to be consulted.

Also, what's in the 'mainly water' that you'll be pumping? Pump resistance to chemicals and/or abrasives might be an issue.