k wastewater pump curve

Home made suction dredge

Home made suction dredge

I'm a prospector, and I have developed a new type of dredge that uses a lot less water than traditional suction dredges do, but performs far better for the same size. The system runs off a pressure washer, but I think the washer I currently have is not powerful enough. Mine is a Troy Bilt with a 190cc Briggs and a pump that has a 2800PSI rating at 2.3 GPM max(but it's more like 1.7 with the narrowest nozzle). I really want to get a commercial unit with at least a GX390 or equivalent and a better pressure pump, but I am limited mostly to used equipment since I am disabled. So we'll see what comes along. I think the guy who I got the current sprayer from damaged the carb trying to repair it. The engine pulses oddly(especially during idle) even though it's extremely clean inside and out. The bottom of the carb bowl is a little crushed, but I am not sure that explains it fully.

I have a new video I took of it in operation. It is now draining a standard container that is about 55-60 gallons in capacity(unfortunately these particular barrels do not say anywhere on them what exact size they are). It fully drains it in almost exactly 1 minute using maybe 1.7 gallons to move 55 gallons(that's a 1 to 32.35 ratio of water used to water moved). It cuts that speed in half(doubling the time needed) if I take the classifier screen off it and let it suck up gravel. I had it moving gravel up an incline after dropping down first and it started to really struggle once the line had about 100lbs of gravel in it. A bigger pump would probably help with it, but keeping those big rocks out is pretty important. This thing could perform even better than this by a lot, but I am still happy that its performing this well at this stage in development. Once I get a 3d printer I should be getting much better results that are easier to tune than a rig made of plumbing parts.

Be warned: This thing sounds a bit like a jet so don't turn the volume up. Hopefully you guys can hear what my engine on the pressure washer is doing.

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is it a venturi system, or do you have an impeller down there?

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It is a venturi design

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Pressure washers do that when no load on them....keep water going through it or you will burn out the pump

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I haven't used a pressure washer yet that would suck water per design. Most require 40 psi and a 5/8" dia hose min.

Guess I am not getting what kind of pump your feeding the pressure washer with.

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At home I use the garden hose outlet, but in the field I have an RV-type pressure pump that pumps a little bit more water than the pressure washer does. It runs on 12-14V reliably, but I really need a couple of lighter batteries when I can afford it. I have a literal ton of sealed lead-acid batteries retired from medical equipment, but what I really want are some lithium equivalents. I am trying to centralize as much stuff on the power washer as possible because it has wheels.

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Power washer should be able to pull it's own water up a small way; I've used mine that way, with the inlet tube dropped into a canal below me. I have 2 of them, both 3-phase 380v electric, 6HP.

I've also used a barrel of hot water fed from a domestic hot water heater, the pressure washer pulls faster than the boiler can deliver so I have to stop for a few minutes of every 15. Hot high pressure water degreases engines without adding anything, also works well to clean sticky bug droppings from the roof of my boat.

Pumps are available separately, but then you have to buy new. Strap it to whatever motor you find.

I also got repair kits with new seals and check valves for my pressure washers, after I figured out who the pump maker was (not the name on the side of the assembled machine).

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I just err on the side of caution and keep an electric pressure pump on the inlet. I don't imagine I'll ever be using hot water for this though. It would kill fish and I don't think it would improve the gold recovery.

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Some washer pump will bypass hot Water. If you want to use hot water make sure your pump isn't one of them.

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I don't think there will ever be hot water involved. I'm not sure why I'd need it and it would kill fish.