DIY Watermaker

[x-ray]

Hi Joe.

Sorry for not having translated my site yet.

All I can say is that the watermaker is giving me water and no headaches.
O.k. I have replaced the Karcher, the pressure gage, one fitting, and one gardena plug. That's it. But it never let me down.
I did what you do with every watermaker I.e. filter changes, flushing and winterizing.

It's a watermaker and that's the whole story.

Cheers

Rainer

[hellosailor]

Joe-
You will find Google Translate (translate.google.com or the Android app) and the Babelfish (babelfish.com which came first on altavista) are both often useful for translations. Sometimes not quite right, but often getting the essence across very nicely. FWIW.

[RaymondR]

I didn't use a stepper just a simple permanent magnet dc motor with integrated gearbox, cheaper and easier to control.

Opened and closed a needle valve about 1,800' deep in a well years ago using a Makita battery screw driver. Stuck the thing in a lathe and machined it down to fit in a 50mm dia stainless tube. I have forgotten how I connected the drive shaft and valve stem. Monitored the current draw as an indicator of fully open close and the impact clutch worked well to unseat the valve.

[ErikFinn]

Originally Posted by Tellie

I scoured E-Bay for pumps, filter housings, and bought parts I really didn't need like 30 sub standard filters I later learned that though they are 5 and 20 microns aren't worth much for an RO system and on and on.

Hey Tellie, I never dared to ask you questions because your profile photo looks so scary.. Haha. But I read elsewhere you are encouraging us mortals to ask questions.. So here I go:
I wanted to ask about the those normal 5 & 20 micron filters, used for dock water filtering or for your water maker prefiltering; are the cheaper ones really so bad? While I wouldn't get the cheapest ones for a WM, but would something like these normal water filters work ok? (photo attached)
Cheers

Edit: despite having tried for an hour or so I couldn't get the photo to attach, so let me just ask if normal 20 and 5 micron paper water filters would work or do they have to be something special?

[ErikFinn]

Originally Posted by Tellie

One thing I'd recommend is using only pleated pre-filters.

Having now read this thread two times I spotted this nugget

[Cheechako]

IME 20 micron is fine for pre filtering a watermaker. I just used the cheap polyester wound ones with no issues. The paper are better. You just need to keep the chunks out really.

[SV THIRD DAY]

With all due respect to our good friend Cheechako, there is not a single water maker company that uses or recommends only using a 20micron prefilter upstream of a RO Membrane. It may not matter to a DIY guy that doesn't have a warranty anyway, but it will also VOID the membrane warranty from every manufacturer. It's not that we have stock in Big Filter and want to hose you down for high priced filter replacements (we sell them for $9ea) but it's just the nature of how RO Membranes work and more importantly how they can fail from particulate blockage.

Take a look at this Video on how an RO Membrane works in regards to the sea water flow path and you can see how particulates would be bad and tend to clog up the extremities, thus increasing your TDS and lowering your product water flow rate.

https://www.youtube.com/watch?v=rK7UVY_7K8w

This is also where anecdotal examples of "it works for me for years" are dangerous because the particle size distribution varies from water source to water source. And different water maker manufactures have different raw sea water flow and product recovery rates that can GREATLY affect how particulate matter is swept (or not) from an RO Membrane. Good RO design and operational practice calls for prefiltering of particulates down to 5micron.


When it comes to Pleated vs String wound or Blown solid prefilters. There is no doubt that the string and blown filters are less money...but they also have a lot less filtering surface area. This may not matter as much on a lower flow water maker or in area's without heavy particulates to filter out, but skimping on prefilters to save a few bucks in my view is penny wise/pound foolish. Excessive pressure drop across the prefilters puts extra wear and tear on both the boost pump and high pressure pumps. Rebuilding and repairing those can coast hundreds of dollars...where quality prefilters are cheap.

[Yachts66]

Ok, Rich if 20 microns is too big, what size is just right?

[fallingeggs]

Originally Posted by SV THIRD DAY

Good RO design and operational practice calls for prefiltering of particulates down to 5micron.

Sent from my iPhone using Cruisers Sailing Forum

[ColdEH]

Ok I know this question has been answered but i can't seem to find it and the tech sheet from DOW does not mention it .

What is the shelf life of a
SW30-2540.



Don't want to buy old ones .


Regards

[SV THIRD DAY]

Originally Posted by typhoon

Ok I know this question has been answered but i can't seem to find it and the tech sheet from DOW does not mention it .
What is the shelf life of a
SW30-2540.
Don't want to buy old ones .

There is a lot of confusion around this question because a "properly stored" membrane doesn't really have a shelf life. But how do you know if the membrane you buy has been properly stored and how do you properly store one yourself?

Once an RO membrane is allowed to dry out it's done it becomes trash. Secondly storing them at high temperatures can break down the organic film that does the RO magic. Then as a bonus if biological growth happens in the membrane while it's being stored that can kill it. The final item that will kill an RO membrane in storage is if it's allowed to freeze the ice crystals will tear and rupture the RO membrane and then it's dead. So that's why DOW ships their membranes in a double vacuum bag with sodium metabisulfite preservative inside the bag to keep it moist and to keep biological growth from happening. The storage temperature for a membrane is 140 degrees Fahrenheit so that's pretty darn hot. So unless it's sat in the back of a truck or the back trunk of a car even an engine room doesn't really get to 140 degrees. (note: the operating temperature for an RO membrane is 120 degrees but with water flowing through the pressure vessel it's pretty difficult to exceed that temperature during operation)

In my experience the reason people think there's a shelf life with an RO membrane is because it's either allowed to dry out or it's allowed to have biological growth. So the membrane they purchased 3 years ago and had in storage is now dead. So as the end of the day a "newer membrane" does have a less chance of being bad because the time period required to take good care of it is less, so your odds are just better that something bad did not happen to it in storage.

When using an off-the-shelf membrane I really don't see any point in storing a spare aboard your boat. They may cost a little more but they are available anywhere around the world and DHL can typically get one to you in under a week for about a hundred bucks to most places around the world. For Cruisers that insist on carrying a spare membrane I think the best way is to put it inside of a PVC pipe filled with pickling solution with the end caps glued on that way it is protected pretty well and will most likely be brand new when you need it vs dried out and dead.

[ColdEH]

Thanks Rich , I want to comision my water maker but I'm not in salt water . I guess I will just run it in fresh , check everything for leaks and proper operation and then pickle the membranes until I get to the ocean , might be a couple of years .

Regards

[SV THIRD DAY]

Originally Posted by typhoon

Thanks Rich , I want to comision my water maker but I'm not in salt water . I guess I will just run it in fresh , check everything for leaks and proper operation and then pickle the membranes until I get to the ocean , might be a couple of years .

Regards

The only "Warning" is that in fresh water you DO NOT take your system pressure to 800psi. You need to stop at about 250-300psi. I made a video about that...

https://www.youtube.com/watch?v=Ht2B3lpFbdQ

[ColdEH]

Yes I saw that video, excellent ! Wish I could find some salt water around here to bring it up to full pressure , don't want to be working on my water maker in New York LOL.

Regards

[dkenny64]

I know this thread is old..

but..
I've learned alot from it...series is the way to go

how much to filter..5 micron before the high pressure pump.. 2micron or less require carbon filters.. 5 is easy with a spun whole house type filter.

in rush surge...are you starting those pumps with the needle valve( high pressure regulation).. closed? if these are open the inrush current surge should be low..low 1.5x running..not 6x..

12v motors..yes they work..there is a guy in my marina that made his watermaker using a 2hp 12v DC motor...no he doesn't run it off batteries(but could) nor solar..he has small 3 cylinder diesel that power two 180amp alternators and a fridge compressor..yep..while making water he freezes his ice box to -10F...fyi he has 10 batteries in main bank.. no solar..no wind..

I just hope to put together a system that runs on 120V( have generator) and make 30-50gal per hour.. if I have to run the generator for an hour each day(1 gallon). while making breakfast, charging the batteries.. OK..for crossings..conserve water..solar to keep everything running..rough guess 10days without making water..we carry 180g of water..

-dkenny