DIY Watermaker

[thatboatguy]

Hi, It sounds to me like you are almost out of the woods! "Ex Fortis Fils Dulce" without googling I'm going to guess that this is roughly "how sweet it is to have an empty nest" ?

Anyway to get to your questions. I know you are in the final stages of the planing process because I was there not too long ago. As for Stainless vs Bronze vs Brass I think the discussion could easily get contentious but it really doesn't have to. For us, and in our particular circumstances, we were able to eliminate brass. Brass and saltwater are too easily susceptible to electrolysis corrosion for my liking. Of course there are ways to mitigate that to a large extent but our budget allowed for the higher reliability of Bronze or Stainless. So with those two choices we decided on Bronze, only to avoid the possibility of crevice corrosion. Possibly I should actually say the "myth of crevice corrosion" because I've never actually encountered it in the dozen or so systems I've had apart at one time or another.

As for membranes and pressure vessels, I google around from time to time and I always find that American RO comes up the winner every time for both. They are vendors of filmtech brand. Possibly you could contact filmtech directly, explain that you are in the UK and are looking for the equivalant vendor nearer to home?

So where do you go from here?

Take your gal per hour number and talk to your filmtech dealer. Once you have your membranes/pressure vessels planed, talk to your giant pump (or whomever) dealer about a pump that will meet your needs. Next, you put a pulley on your generator front end that delivers the right RPM to turn the pump at the desired RPM.

Bada Bing Bada Boom! Ample fresh water.

I hope this path helps lead you out of the woods.

George

[anjou]

Thanks George.
Translation literally means, 'From strength comes sweetness' (Dulce - honey)

First job is to check the details with the Captain and confirm genset constant revs, typical water useage, genset run time, pump capacity, pulley sizes etc.

What chemical is needed to pickle the membrane for prolonged off use storage?

[thatboatguy]

Originally Posted by anjou

Thanks George.
Translation literally means, 'From strength comes sweetness' (Dulce - honey)

So much for my Greek...

Originally Posted by anjou

What chemical is needed to pickle the membrane for prolonged off use storage?

Sodium Metabisulfite is what we use to pickle membranes. You can pay one of the big guys, big money for it or you can get it from a food service company bulk for very little money. We found it cheap on Ebay.

George

[anjou]

Yeah, it was all Greek to me too, untill I learned a little Latin.

I used to use sodium metabisulphide to cleanse home brewing equipment. Bought it in jars as a powder and made up a solution with water. Also add a tablet to finished bottles of wine to prevent further fermentation so the wine will clear.

Ive just been on the American RO site and noticed they have rotary type pumps. Are these suitable for watermakers and what are the advantages if any?

[thatboatguy]

Originally Posted by anjou

Thanks George.
Translation literally means, 'From strength comes sweetness' (Dulce - honey)

So much for my Greek...

What chemical is needed to pickle the membrane for prolonged off use storage?

Sodium Metabisulfite is what we use to pickle membranes. You can pay one of the big guys, big money for it or you can get it from a food service company bulk for very little money. We found it cheap on Ebay.

George

[thatboatguy]

Sodium Metabisulfite

Synonyms: Pyrosulfurous acid, disodium salt; Sodium Pyrosulfite; Disodium Salt Pyrosulfurous Acid; Sodium disulfite; Disodium disulfite; Disulfurous acid, disodium salt

George

[thatboatguy]

I just looked at the specs on the rotary vane pumps on the ARO site. Not enough pressure to be considered for desalination.

Sorry about the double post.

George

[anjou]

So i need a bronze piston pump capable of delivering @800 psi with volume 4x my daily needs for product?

Captain says we can run it from the 24v side of the genset batery charger because the main engine alternator is also 24v and will be easy to swap over in case of genset failure. Im thinking of a truck starter motor with the bendix removed and appropriate size pulley to run via vee belt to pump.

[thatboatguy]

Well... you are off into uncharted territory for me. How do you say "the student becomes the master" in greek...?

Keep us posted.

George

[anjou]

Dunno George, im trying to learn Latin, but when we get to Greece next year I will be sure to ask.

Whats the safest most fool proof way of testing the product after first start up passes have been dumped? The Captain, in his medical capacity tells me it doesnt take much saline in the kidneys to do a lot of damage.

[hmmm]

I have been visiting this side regularly put only decided to register today.
The development of Opencpn is of great interest (congrats to the producers for this masterpiece). Most posts with generator and solar i followed and also the watermaker discussion. I'm also looking at building or buying a water purification system (not necessary making it, just converting seawater to beer ).
Does anybody have a 'new generation system' installed without the high pressure pump, and as-with low energy consumption.
The ready 35 from schenker.it looks like the ideal piece of hardware.
The system by the looks of things is almost ten years old so there should be some reviews around.
Any feedback is welcome.

thanks

[thatboatguy]

Those watermakers do have a high pressure pump. It's simple a different kind. They utilize a boost pump.

George

[thatboatguy]

For product water testing you can purchase an inexpensive PPM tester on ebay, also available from salt water aquarium supply houses.

George

[anjou]

I gathered some info at the Southhampton boat show and saw a couple of demo machines working. Lots of moving parts which will one day wear but the design does mean they use less power even though the overall pressure is still high (800 ish psi)
excess pressure from one side of the double sided pump is fed back to help push the piston in the opposite direction.

Damn expensive too.

[hmmm]

Thanks for the info. The freshwater creation really gives me a headache. I just don't like the high pressure-seawater combo. The schenker unit is a nice package put to expensive.

Now what are the thoughts, comments in general for the Whisson Windmill. Reading the article I encounter a lot of ifs and hopefuly. Also the lack of a working prototype is a bit sus. I be happy to get just 7 liters a day not 7000 liters, wich seems not possible. Now the windmill is not on the maked yet, however there are other watermachines sold right now (last two links). Desalination works that is certain, but on the ocean it might just be good enough for a shower and wasching. Is it worth to wait for a year or so and see what happens to the windmill, or will the invention just evaporate into thin air?
thanks for feedback

Maxwell Whisson - water windmill - air well


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