DIY Watermaker

[goboatingnow]

Originally Posted by x-ray

Yes, it-s true,
Kärcher says the smallest Model of it-s range, the K 2.14 or similar, which i actually use, is for occassional small jobs only.
I guess that is exactly what i am doing, every 3 or 4 days i have it running for an hour up to 90 minutes. No problems so far, ventilation is an issue...
The plungers are made of stainless steel, but not a 100% saltwater resistent grade, so flushing the system after use is essential, what means 15 Liters (or 15 minutes) of initial production go down the drain after each run.
Life expectation of the Kärcher pump will be one to two years, depending on hours of use, so its prudent to have a spare Kärcher on board,
but for 60 Euros, i may use up 20 Kärchers in 40 years before catching up with the costs of a CAT or Wanner pump. Don-t think i will still be sailing in the age of 100....
The output of the Kärcher is at the minimum side of the parameters given by filmtec, at 1.3 gallon (4 to 5 Liters) per minute at operating pressure, that is why i don-t expect my membrane to last as long as in configurations producing higher feed flow.
Future will tell, but membranes are getting cheaper as well,...
I plan to install a second membrane to increase output to 100 L/h.
Will let you know how this worked out..
For the ones who can read german,
this is my watermaker-site
http://watermaker.jimdo.com/
Regards
Rainer

PS:
Pics below show test run in my backyard

Rainer , will the Karcher provide enough flow at the designed pressure for two modules. If they are in series have you reserve pressure or of in parallel have you enough total flow at the operating pressure ?


It's also easy to buy the pump heads from the suppliers. Many are made in Italy
Dave

[x-ray]

Hi Dave,
in series installation is the only option, parallel, no way.....
Flow will be at the minimum limit for the second membrane, just....
Pressure can be regulated up to 70 bar (1000 psi) before the Karcher switches off automatically, so that is no problem,
of course, higher pressure equals lower flow.
At operating pressure with the Karcher on full revs, (I can tune it down by using a power control device, for soft start) it will give roughly 4 to 5 liters per minute to the first membrane, resulting in 3 to 4 liters at the second membrane, resulting in a concentrate flow (Brine output) of the second membrane of some 2,5 to 3 liters per minute.
Filmtec says, 3,3 liters (1 gls) per minute is the required minimum concentrate flow for the standard SW 30 2,5"x40" membrane.

Look here at page 82

http://www.dow.com/scripts/litorder..../609-00071.pdf

As you see, two membranes in series will be slightly below the minimum limit.....probably resulting in a shorter live expectation for the second membrane. But for a couple of years it will be fine, i guess.

Kärchers are made entirely in Germany, i-ve been told...
At the price for the Kärcher, i don-t care anymore about the pump-assembly,
if the Kärcher goes kaputt, or sounds funny, or gives any problem, whatsoever, i just put in the spare one, a one minute job...

[hellosailor]

I would think that as long as you have a spare Karcher, or intend to buy spare pistons, that you could easily (ha) give a set to a machine shop, or use an online machine shop, and have a new set either fabricated from a better material, or treated to be more resistant, i.e. with some type of plasma spray or chemical surface treatment. As "consumers" we never see this stuff but it is routine metallurgy and machining in commerce, so the hardest part should be locating a shop that will handle it.
Of course at 60€ you probably can't get a machine shop to open the front door these days, but that's another issue.

[x-ray]

The Kärchers aren-t made to last forever anyway.
The brushes in the motor wear away, the sealings will fail,
the gearbox is lubricated in oil, that cannot be changed easily etc.
Let-s face it, it is a disposal item made to last 2 yrs when in use regularly,
like so many things nowaday, but cheap....
Regards
Rainer

[jgbrown]

Originally Posted by Sam Plan B

I have been wondering lately about an alternative to a conventional WM. It seems to me that forcing sea water through a semipermiable membrane takes an awful lot of energy. Besides, there is the problem of filtration to remove sediment when at anchor. However, compressing gas does not require so much force. So, since we are always in an atmosphere of 100% relitave humidity, can a WM be made that produces condensate on a coil. The condensate would be harvested and piped into the boat's water tank. It would always be pure water without the problems of sediment filtration.

Also, years ago there were air conditioners on the market that worked on amonia. I believe Arcal was one brand. The amonia was in a closed loop. When it expanded it absorbed heat. When the amonia was fully expanded it would condense to a liquid. The liquid amonia would be pumped throug a tubing section that was exposed to a gas flame. The amonia would expand again and repeat the circuit. So, can a WM be made that operates with a propane flame and a 12v circulating pump? Just wondering.

Yes, though they are usually straight electricity power. they don't work on boats though.

[jrambo316]

Originally Posted by foggysail

plus flow transducers and one high pressure transducerFoggy

Do you have examples of where to source these transducers? My quick search yielded pretty expensive stuff that might quickly reduce the DIY value. I have some interest in micro-controller applications for cruisers.

[Yachts66]

Sounds like the same principle behind your normal everyday dehumidifier. I think the problem there is the amount of water gained per watt used.

[foggysail]

Originally Posted by jrambo316

Do you have examples of where to source these transducers? My quick search yielded pretty expensive stuff that might quickly reduce the DIY value. I have some interest in micro-controller applications for cruisers.

Mine are made by Sika that use Hall sensors. They are made of plastic wit a sealed magnet and SS pins. The part number is VT1540KSWANN01. The operating range is from 2-40lpm.

I purchased mine on Ebay but I forgot what I paid for them, most likely in the $40-50 range.

I want to add a general comment. I do believe using sensors is a better way to go rather than using the glass tube devices. But there are buts. I started my project 2 years ago with the idea I would have it installed by that spring. My original approach was to keep it relatively simple but use discrete electronics for the controls. And then came Dave, GoBoatingNow.

Dave is an active design engineer engaged in day to day embedded control designs. He is one smart guy. My background is also electrical engineering but I retired over 20 years ago and I had never use C for software design. I decided to use a microcontroller. Yes, mine is about ready for installation next spring, I am lacking only filters and the membranes.

Sure, I learned quite a bit, my system has a simple small panel that will control everything. It is fully automatic. But it has taken a lot of time to get there especially because I am too busy with many other things that only give me about 3 months during the colder weather to build the project.

Another thing I want to warn about. If you plan to use a large AC motor, 2+hp for a high output system, be prepared to face the inrush current (locked rotor) problem.

Foggy

[thatboatguy]

On our very simply designed Frankenmaker I flipped switches and turned valves for two cruising seasons. All in all we used it as our public works department for about 18 of those 24 months with it pickled while at the dock here for about 3 months each summer. I never once back flushed the silicon bronze hp pump and it has shown zero wear that I can detect. It kept our freezer and refrigerator working and our batteries topped up all that time too with one alternator failure and one refrigerant leak, both easily repaired by me in the field since I brought my vacuum pump and gauges along with me as well as alternator spares. It has been hands down the most reliable equipment item on the boat so I can't speak highly enough of keeping things as simple as possible. In fact, the single electronic device on the Frankenmaker (the regulator on the alternator) failed! The simplified electro-mechanical portions just kept on keeping on.

I'd also like to point out that with the efficiency of direct mechanical drive from the little diesel motor, we could not have raised anchor, driven the boat to the fuel dock for a water fill and then re-anchored for less fuel than we spent making water right where were. Far less time and fuel consumption compared with the jerry-jug/dinghy option.

The one thing I do not like about the unit is the noise. It's very loud onboard while running although with the wet exhaust, the noise did not carry far outside the boat and never bothered anyone else in any anchorage.

George

[hellosailor]

" However, compressing gas does not require so much force." "Much" is relative. High pressure gas condensors require a lot of power and generate a lot of waste heat. They also tend to need lubrication and filters and lots of routine ongoing maintenance parts, there's nothing cheap about them especially on the small scale.

And all you have to do is visit your local service station and use their compressred air (tire hose) to see how the squeezing out of water goes.

" So, since we are always in an atmosphere of 100% relitave humidity"
Nope. Even in a heavy rainstorm, the relative humidity can be fairly LOW. Yes, the ocean is damper than Pheonix but that's still not 100% all the time.

" can a WM be made that produces condensate on a coil."
You buy one for about $150 at any appliance store, they're sold to keep basements dry and called "dehumidifiers". Even if you find one with copper coils, you'll also be warned not to drink the condensate because airborne bacteria, fungus, dirt, are collected along with the water and it can get real tasty, even with routine cleaning.

On the bright side, at least two teams are working on nano-structured material patterned after the shell of some desert bugs. Apparently the microtexture and hydrophilic surface attract water from the air, which then trickles to a collection point. It works well enough to keep the bugs alive but they're blue-sky hoping to one day make a water bottle that will suck three liters a day out of typical air (over land) to keep refilling itself.

[Therapy]

Originally Posted by hellosailor

"
they're blue-sky hoping to one day make a water bottle that will suck three liters a day out of typical air (over land) to keep refilling itself.

Then there will be a thread about how much deck space should be allotted for nano water sheets and how much for solar paint.

[goboatingnow]

Originally Posted by foggysail

Mine are made by Sika that use Hall sensors. They are made of plastic wit a sealed magnet and SS pins. The part number is VT1540KSWANN01. The operating range is from 2-40lpm.

I purchased mine on Ebay but I forgot what I paid for them, most likely in the $40-50 range.

I want to add a general comment. I do believe using sensors is a better way to go rather than using the glass tube devices. But there are buts. I started my project 2 years ago with the idea I would have it installed by that spring. My original approach was to keep it relatively simple but use discrete electronics for the controls. And then came Dave, GoBoatingNow.

Dave is an active design engineer engaged in day to day embedded control designs. He is one smart guy. My background is also electrical engineering but I retired over 20 years ago and I had never use C for software design. I decided to use a microcontroller. Yes, mine is about ready for installation next spring, I am lacking only filters and the membranes.

Sure, I learned quite a bit, my system has a simple small panel that will control everything. It is fully automatic. But it has taken a lot of time to get there especially because I am too busy with many other things that only give me about 3 months during the colder weather to build the project.

Another thing I want to warn about. If you plan to use a large AC motor, 2+hp for a high output system, be prepared to face the inrush current (locked rotor) problem.

Foggy

Hey foggy how's it going man

Dave

[foggysail]

Hi Dave--

Between fighting tenants, code enforcement directors my adobe has gone somewhat to pot. I just got back to the important thing in life, the project....Wifey surely will take a stand against that but in general things are moving forward. By now you must be into things far beyond my level. But I must admit, this stuff is like a narcotic to me.....and I don't even know what grass/pot smells like.

How are YOU doing? Last you mentioned something about staring a company. Hope things are going well for you.

Wifey has plans to spend some months in Florida where I might go but only for a short visit. There is just too much on my plate that I need to finish. The *&^% of mine MUST get ready for installation this spring. Notice I mentioned in my above post a warning about motors and of course my system has a 2hp 1750 single phase motor. A couple of weeks ago I removed my high pressure pump from the motor/pump assembly to test the motor for correct rotation required by the pump. Plugged the motor into power and surprise surprise.

I know about lock rotors but I never expected to see almost 150 amperes of surge that I thought would cause my 20 amp circuit breaker to launch into the unknown! Anyway, I fixed that little problem with a couple of relays and contactors so the motor initializes on the 240vac winding minimizing the locked rotor surge and after a couple of seconds reverts back to the 120vac windings.

But enough of that. Stay healthy (I am fortunately) and I will keep in touch. Pictures later when I can be proud of my hardware display.

Foggy

[x-ray]

As I wrote last year, our Karcher system proved to be very reliable. We spent 9 months on the boat last year, with the watermaker producing most of our water during this time. This system is sort of spreading around in the german/austrian sailing community, and i have helped many of them getting all the parts together.
By now i know of four Karcher systems, having two membranes installed in series, one system serves on a charter catamaran, where each crew gets a short instruction on how to operate the system.

All these two membranes systems give around 110 Liters/hour in the Med, where salinity is very high,
although flow rate to the second membrane is slightly below the filmtec parameters, no problems so far.

Of course, it is not very energy efficient, and the Karcher is noisy, but it is very money efficient, probably the worlds cheapest watermaker...

[JoeBee]

Hi Rainer

How has the watermaker worked over the last year?

I have looked at your website but unfortunately can't read German. Is there something available in English?

Thank you

Cheers

Joe