Pressure washer watermaker

[beau]

I was planning to build the watermaker system in index which uses a Cat pump, but after listening to you guys it does seem that big is not always better, and that it may be better (and cheaper) to have a smaller unit that you run more often.

I have an electric high pressure washer that I could use. It is rated at 360 liters /hour (100gallons/hour) and has a maximum of 1,250 psi. I plan to set it up for test purposes and run it at the 800-900 psi and measure the flow rate at that pressure.

I don't expect the flow to be much more than 150 gallons and hour which will only give be 12-15 gallons and hour of fresh water, but I could probably live with that.

Anyone out there with experience or referral information that would be of benefit.

[northerncat]

check here for soem info from someone whos been there and done that
Easytalking :: View Forum - Galley
sean

[Brent Swain]

Bigger is better. You only have to run it for a few minutes twice a week. Smaller units have to be run for an hour or two to make enough to flush them properly, which rarely gets done, which is why they have so many breakdowns.
It takes under a thousand dollars to make a 540 gallon a day unit. Why would you pay three times that for a smaller one.
Brent

[northerncat]

where do you source your pumps to get them for that money louis
sean

[Brent Swain]

Any pressure washer pump with more that 3gpm output and ceramic plungers will do. I bought mine, a general TT911 for $325 CDN from Mancorp in New Wesminster, but I have seen them on sale at Princess auto for cheaper.Pressure washer pumps are a lot more robust than the pumps they make for watermakers, especially Italian made pressure washer pumps.
The membrane fits perfectly in standard 2 1/2 inch sch 40 stainless pipe . All you have to make up is the ends. My book tells you how to do that. Thus its easy to make your own membrane housing. The rest is just hose, valves and v belt parts.
Brent

[beau]

Sean,
I have ordered a petrol 6.5 hp pressure washer from ebay for AUD$ 399.00 it has over 3 gallons a minute and 2600psi I doubt that you get 3 gal at 2600 psi. I will run it at 800-900 psi and test the gallons per minute when I get it.
I have also ordered 2X 2.5 by 40 inch membranes form the USA plus pressure cyclinders.
I will let you know how I go.

[bill good]

Add me to that list You are ahead of me.
All ears for now.

Sean I'am off to look at lites today Ths

Regards Bill Goodward "GoldRush" BNE

[northerncat]

i must admit im very interested as to whether you will get slightly more flow by running the pump at a lower pressure setting, sounds like an interesting setup beau
sean

[InezWashington]

Hi everyone,

What is the ideal brand of pressure washer that is best to use?

[Pizzazz]

Pressure washers are not a good way to start for a DIY watermaker. The pumps (even with ceramic plungers) do not work with salt water well, corrode and need to be replaced often. They are incredibly noisy. The AC motors are low cost and inefficient and mounting the pump on a standard heavy duty motor is not straightforward. Search the web, the topic has been discussed at length. I advise against it.

You are much better off with a cheap AR pump and a matching DC motor. If you still want to experiment with pressure washers, Karcher is a good way to go as their pumps are mostly plastic but again, it will be a waste of time at the end.

One consideration for DIY watermaker is to decide from the start if you want to make potable water (for drinking and cooking) or just fresh water for cleaning, laundry and bathing. The potable water route requires potable hoses, pumps, fittings... it is a higher standard and by the time you source all the parts you will be better off buying one of the kits from ebay or the Cruise RO. Alternatively, you buy drinking water as most of us do at home anyway (2.5 gallon containers work really well) and use the watermaker for the other needs. In any case, you need to bring as much beer as mineral water, so it is not so bad.

[GordMay]

Greetings and welcome aboard the CF, Inez.

[Polar Opposite]

Originally Posted by Brent Swain

My book tells you how to do that. Thus its easy to make your own membrane housing. The rest is just hose, valves and v belt parts.
Brent

Brent, what is the book you are referring to?

[DGH]

Cheap pumps will work but not for nearly as long as a Cat pump will. Very fine pre- filtration of the sea water feed will help. Not coarser than 5 microns and 1 or 2 would be great. Good luck.

[bcboomer]

Originally Posted by Polar Opposite

Brent, what is the book you are referring to?

That would be Brent's Origami Boat Building book. I think you can buy it directly from him. Actually pretty interesting reading even for us plastic boaters.

[phorvati]

I got my watermaker pump cat 290 (carwash pump) for 90$ on ebay. Granted i bought 150$ worth of service parts, kits etc, but i can say that Cat290 is a very common pump. Therefore parts are affordable. Ive been using it since 2009. I do have to service the internals every few years. And then finally last year i ran into cat 331 all stainless pump for around 300$ also on ebay. Ive been waiting for that one for years to come. but 290 is a great little nickle brass pump. It drives 2x 40" membranes in parallel with plenty of flow.