small electric pressure washer pump for watermaker

[tonejunkie99]

I was wondering if anyone has tried to incorporate parts from a small electric pressure washer into a reverse osmosis watermaker... The amperage draw factors out to being around 6 amps and I calculated with the pump's 2000psi, and 2 gal per minute delivery to harvest almost 40 gallons in an hour through a 2 membrane system, so basicly one of our 240 watt solar panels should run this system, and at 1 hour a day should keep our water tank full and then some... I dont expect the pump materials will resist salt corosion for very long, but the pump is supposedly stainless steel lined... at the very least, with the motor and pump being together it seems like it could be a good start-up system, and be swapped out at a later date for a heavier duty engine mounted CAT pump... Our boat has a very easily accessed engine compartment (all 4 sides)... I am a welding contractor and fabricating the brackets and getting it mounted to the engine are not the issue... the problem with my boat is that there is not much room inside the compartment when the compartment panels are in place, so It's possible I may not have enough room for mounting one to the engine...

[Omatako]

Given that the average membrane requires only about 850psi to produce fresh water, you'd have to regulate the pressure down (but then you already know that).

I'm busy building a watermaker myself at the moment so your pump is of considerable interest to me.

I have a 3 cyl CAT pump that I plan on using on the main engine but also multi-tasking it with an electric motor with a magnetic clutch to seperate the drives as required. The electric motor I have been advised to use is a half-horsepower AC motor that takes quite a lot of juice from the battery bank via the inverter. I would not have thought there was a 2000psi pump that delivers 2 gallons a minute that could run on a 240w solar array. But I'm very happy to be educated.

So I'd be most keen to know the identity of the pump/motor combination and given that it is able to run off your 240w solar array I assume the motor is 12v. If it is a 110v motor (if it comes from a domestic pressure washer then it probably is) then your solar array will only provide about 2 amps not counting losses due to inversion.

And what size membranes are you planning on using that deliver 20 gallons an hour each? I have two membranes that admittedly are quite small but they only deliver about 35 litres (less than US 10 gallons) an hour each at 850psi.

[Hartley18]

Originally Posted by tonejunkie99

I dont expect the pump materials will resist salt corosion for very long, but the pump is supposedly stainless steel lined...

Have you thought about fitting a back-flush system??

Even if it's only a hose connection for use dock-side, you will need one to get rid of the salt...

[mitiempo]

I'm not sure if this will help but it is probably worth a look at least.
http://www.westward-ii.com/PDF's/How...watermaker.pdf

[RachelRoberts]

Hi,
All you've said below is true, but multiple units turning water flow into electricity that run only when some one is going to use the water any way would more then offset the cost of the water itself plus feeding electricity back in to the grid. Further, the idea is to not try to get big gains, but for thousands of households to install such units obtaining a very small gain from each. Even installing such units in gutters would garner a little bit of electricity.
http://www.best-pressure-washer-revi...r-ratings.html

[tonejunkie99]

I may have over estimated the production of the membranes, it seems they only produce around 10 gal each in real life... still plenty... I upgraded to a 280 watt solar array that is charging a bank of 4 AGM batteries, and I also have another bank of 4 that i am in the process of tieing into the system with a sunforce 600 watt wind turbine. I am currently using a xantrex mppt controller to regulate the charging, and using a xantrex true signwave converter to power a small refrigerator, and intermittent use of a tv, microwave and laptop computer... I do also have an additional 280 watt solar panel, but I really hope the addition of the wind generator will kill the need of a 2nd solar panel because these 280 watt giants are 33" x 77" in length. there is room behind the split backstay for one panel across the rear of the bimini, but there is only 33" of room between the back stay and end of the boom which leaves no clearance...