Topics

Water maker Questions


John Clark
 

Hi Mark,
  As Bill says the Dessalator is a good design.   There are parts available and support form Amel and the Amel Owners Group, I would suggest sticking with it and doing a ground up rebuild

When I bought Annie (SM37) the previous owners had not used the watermaker in over eight years so it was a known project. I suspect your watermaker may be in a similar state.  The good news is that it is fixable with a little bit of time and patience.  I recovered my watermaker replacing the membranes, the membrane endcaps (precautionary as they were original and had stress cracks) and the high pressure hoses(also a precaution).  The pump needed to be disassembled and cleaned before it would build pressure but it was pretty easy to do.  Once back together she ran fine.  It sounds like your pump is functioning so you are probably good there.

The worst issue with the Dessalator was the early control system which as you found out does not actually test the water quality.  I deleted that whole bit of junk and test the water myself before sending it to the tank. I currently have the product water discharging to a free hose that I allow to flow into the cockpit when the unit runs.  I sample with a portable TDS tester then put the hose into the fill nozzle when it is good quality. Nothing goes into the tank without monitoring. I think Bill suggests doing that somewhere below.  That is the best way to ensure your getting good water. And that can be very important if you are underway relying on your tank for potable water.   One bad batch from the WM and poof you have no water at all.

To get SW into your tank you either have a bad o-ring or the membranes have been damaged.  Ether way replace the membranes and o-rings and you are good, and will know for sure the condition of the membranes.

Thoughts:
I installed my membranes in 2017, they are still running just fine.  Run the WM every once in a while for a few hours, never pickled it.   If the boat will be idle, I flush them with fresh water.
Check the end caps on your membrane vessels for signs of cracking.  I think Dessalator has new material available now that won't become brittle.
When you reassemble, watch your hoses when the unit is running, make sure they are not rubbing on anything.
Verify the pressure gauge is reading correctly.  My gauge is not the red/green version but read in Bar.  It is reading 15Bar higher than actual.
Change pressure slowly.  Both up and down.
Run the unit with no pressure to flush the concentrated brine out of the system after you are finished making water.
 I bought a solenoid valve to be able to test the water at the galley sample port and then flip a switch to sent it to the tank.  That is a better solution, but I have been lazy.  
Portable TDS /conductivity testers are cheap and available online.  

Regards,  John Clark
SV Annie SM 37
St Thomas USVI

  






A couple of suggestions


 

I suggest that you need to back up some from your assumptions and take a different approach. First of all, if you pay £500, for SW302521 Filmtec membranes, you are definitely overpaying. They should be about $200USD plus VAT/Freight. There is one membrane manufacturer in the world, so it makes no difference where you buy membranes.

Allow me to make a few points:
  • Your Dessalator watermaker is probably 17 years old if it is as old as the SM. Most other brands do not last that long. Dessalator is a modular design which means modules can be replaced or overhauled.
  • There can be other causes for a water maker not working. Membrane tube seals could be one of them. 
  • If there is a membrane failure, it may be only one of them.
  • When a watermaker has been neglected and not used, you should allow it to run for at least 30 minutes, discarding all product water before testing.
  • Membranes require moisture. If a membrane is allowed to dry, it will probably never work again.
  • Some water maker manufacturers promise a lot and deliver very little. Dessalator is not one of these manufacturers.
I suggest that once you put the Dessalator water maker in good working condition that you religiously do the following:
  1. Rinse the membranes weekly following the instruction, or run the watermaker every 3 days.
  2. If you do not have a method of discarding produced water from the watermaker, add a 3-way valve to do this.
  3. Before you add any water to the tank, test it. You will find that the TDS will decrease as the watermaker run increases, usually allowing 300TDS or less after 5 minutes.
I hope this helps you.

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar


On Sat, Sep 5, 2020 at 1:31 AM Mark Barter <markbarter100@...> wrote:

This is a really useful thread. 


Nunky is fitted with a Dessalator D100. We assumed that the green light meant it was working well. When it became apparent that it wasn’t we had a tank full of brine. I now know that the green light means nothing. I actually tested the output against sea water and somehow it was worse.

I have no idea when the water maker was last used but my guess is months and months before we bought the boat. Due to various issues including Covid we were then away from the boat for months. I didn’t know about pickling and regular flushing at that stage so it’s hardly surprising that the water maker isn’t working properly.

I am going to clean the membranes to see if that helps but if it doesn’t it’s either 3 new membranes at £500 each or a new system with proper quality control. 

Has anybody managed to successfully resurrect a system from this state? If so, how?


--
Mark & Nicky Barter
S/V Nunky
SM 110


Mark Barter
 

This is a really useful thread. 


Nunky is fitted with a Dessalator D100. We assumed that the green light meant it was working well. When it became apparent that it wasn’t we had a tank full of brine. I now know that the green light means nothing. I actually tested the output against sea water and somehow it was worse.

I have no idea when the water maker was last used but my guess is months and months before we bought the boat. Due to various issues including Covid we were then away from the boat for months. I didn’t know about pickling and regular flushing at that stage so it’s hardly surprising that the water maker isn’t working properly.

I am going to clean the membranes to see if that helps but if it doesn’t it’s either 3 new membranes at £500 each or a new system with proper quality control. 

Has anybody managed to successfully resurrect a system from this state? If so, how?


--
Mark & Nicky Barter
S/V Nunky
SM 110


Porter McRoberts
 

Great intel. Thank you all!
Testing today. 
Porter 

Porter McRoberts 
S/V IBIS A54-152
WhatsApp:+1 754 265 2206
Www.fouribis.net

On Sep 4, 2020, at 2:00 AM, Craig Briggs via groups.io <sangaris@...> wrote:

Not sure what your "green zone" translates to in bars as I have a gauge with numbers and 60 bars +/- is where these operate (actually I usually get good tds at 850 psi / 58 bars). These pumps typically deliver up to 69 bars / 1000 psi, which would be a fine pressure at which to test.
--
Craig - SN68 Sangaris, Tropic Isle Harbor, FL


Craig Briggs
 

Not sure what your "green zone" translates to in bars as I have a gauge with numbers and 60 bars +/- is where these operate (actually I usually get good tds at 850 psi / 58 bars). These pumps typically deliver up to 69 bars / 1000 psi, which would be a fine pressure at which to test.
--
Craig - SN68 Sangaris, Tropic Isle Harbor, FL


Barry Connor
 

Hi Porter,
Both brass fittings have just been replaced on the pump by me, in and out a few times.  The high pressure side broke off completely and the low pressure/inlet had a hairline crack. I only discovered the hairline crack after it was all back in place. Getting the broken thread out was fun! The brass fittings that I used for replacement were thicker than the original. I did use tape, I will monitor this for now but will probably take it out again and reseal the brass fittings with some type of locktight.
 Could anyone tell me if I should  I use Stainless Steel? I don’t like changing things, Olivier told me when we bought that we should keep everything the same.
Thank’s for the information about not using tape.
See photo below:

Barry and Penny
“SV Lady Penelope II”
Amel 54.  17
Sainte Anne anchorage Martinique 


On Sep 3, 2020, at 22:22, Porter McRoberts via groups.io <portermcroberts@...> wrote:



Gary et all I’ve read this thread a bunch and it is super helpful. Thanks for all your insights, and others. 

I’ve removed our cat pump several times in the past week and it’s a real bear. Issue: leaking at high pressure from somewhere around the head.

I’ve taken our 160 to a cat repair place here in Tahiti, thinking I found the leak and needed a new head. Long story short, they found a small hole in the brass elbow going up to the blue stabilization bulb. They think that’s the issue. I am skeptical. Since install and removal is several hours and horrible on the back I’d like to know if anyone knows what pressure the pump is rated for, and also what peak pressure I can reasonably expect  to see when running the pump. It seems like 60-65 bar would be that number, aiming for 56-58  

The guys at the shop pressure tested it to 30 bar with no leaks. I am asking them to retest to 60. They say that’s the maximum the pump is rated to. Is that true?  

What Bar is the low end of the green zone, and the high end of the green zone, assuming my guage is accurate, which I suspend mine not to be (we make 200+l/hr still well below the end of the green zone)?  

I’dlike this to be my last trip behind the generator for a while!!!

many thanks to all

Porter McRoberts 
S/V IBIS A54-152 
Tahiti. 


Porter McRoberts
 

Thanks Nick!  I appreciate it. Yes. That’s the elbow. They have others in brass here too. They’ve worked up the pump with another brass one. And also used Teflon tape to seal the high pressure threads, I was told not to use Teflon by Dessalator, rather the Locktite 542. Which, when I use, it does not leak. Funny to have high pressure hydraulic fittings on one side, and garden hose variety fittings on the other side, both with the same pressure. 

They guys seem very confident in their assessment on the pump. Lots of other cat pumps lying around adding to the gravitas of their opinion.

I’ll ask them to pressure test to 65 bar. I want a failure in their shop. Not the Tuamotus!  

Good luck with your Haulout. 

Porter

Porter McRoberts 
S/V IBIS A54-152
WhatsApp:+1 754 265 2206
Www.fouribis.net

On Sep 3, 2020, at 5:58 PM, ngtnewington Newington via groups.io <ngtnewington@...> wrote:

Hi Porter,
When I bought Amelia, the 160 litre per hour 220v watermaker produced a fine mist of salt water. It turned out to be that Brass Elbow between the CAT pump and the pressure bulb that you refer to. There was a small pin hole!
I went to “Watermaker Services” in Antigua and showed him the elbow. He said that fitting is not rated for high pressure and sold me a stainless one for $5. 

Never had a problem since.
By the way he pumped up the bulb with some gas ( can not remember, what gas, nitrogen?) and said it should be pumped up ever couple of years.
I asked him it’s purpose; he told me it was like a cushion or damper for the system when the CAT pump kicks in.
So could be an easy fix...

Nick
Amelia in Leros getting ready to haul out and head home.
AML 54-019


On 4 Sep 2020, at 05:22, Porter McRoberts via groups.io <portermcroberts@...> wrote:



Gary et all I’ve read this thread a bunch and it is super helpful. Thanks for all your insights, and others. 

I’ve removed our cat pump several times in the past week and it’s a real bear. Issue: leaking at high pressure from somewhere around the head.

I’ve taken our 160 to a cat repair place here in Tahiti, thinking I found the leak and needed a new head. Long story short, they found a small hole in the brass elbow going up to the blue stabilization bulb. They think that’s the issue. I am skeptical. Since install and removal is several hours and horrible on the back I’d like to know if anyone knows what pressure the pump is rated for, and also what peak pressure I can reasonably expect  to see when running the pump. It seems like 60-65 bar would be that number, aiming for 56-58  

The guys at the shop pressure tested it to 30 bar with no leaks. I am asking them to retest to 60. They say that’s the maximum the pump is rated to. Is that true?  

What Bar is the low end of the green zone, and the high end of the green zone, assuming my guage is accurate, which I suspend mine not to be (we make 200+l/hr still well below the end of the green zone)?  

I’dlike this to be my last trip behind the generator for a while!!!

many thanks to all

Porter McRoberts 
S/V IBIS A54-152 
Tahiti. 


ngtnewington Newington
 

Hi Porter,
When I bought Amelia, the 160 litre per hour 220v watermaker produced a fine mist of salt water. It turned out to be that Brass Elbow between the CAT pump and the pressure bulb that you refer to. There was a small pin hole!
I went to “Watermaker Services” in Antigua and showed him the elbow. He said that fitting is not rated for high pressure and sold me a stainless one for $5. 

Never had a problem since.
By the way he pumped up the bulb with some gas ( can not remember, what gas, nitrogen?) and said it should be pumped up ever couple of years.
I asked him it’s purpose; he told me it was like a cushion or damper for the system when the CAT pump kicks in.
So could be an easy fix...

Nick
Amelia in Leros getting ready to haul out and head home.
AML 54-019


On 4 Sep 2020, at 05:22, Porter McRoberts via groups.io <portermcroberts@...> wrote:



Gary et all I’ve read this thread a bunch and it is super helpful. Thanks for all your insights, and others. 

I’ve removed our cat pump several times in the past week and it’s a real bear. Issue: leaking at high pressure from somewhere around the head.

I’ve taken our 160 to a cat repair place here in Tahiti, thinking I found the leak and needed a new head. Long story short, they found a small hole in the brass elbow going up to the blue stabilization bulb. They think that’s the issue. I am skeptical. Since install and removal is several hours and horrible on the back I’d like to know if anyone knows what pressure the pump is rated for, and also what peak pressure I can reasonably expect  to see when running the pump. It seems like 60-65 bar would be that number, aiming for 56-58  

The guys at the shop pressure tested it to 30 bar with no leaks. I am asking them to retest to 60. They say that’s the maximum the pump is rated to. Is that true?  

What Bar is the low end of the green zone, and the high end of the green zone, assuming my guage is accurate, which I suspend mine not to be (we make 200+l/hr still well below the end of the green zone)?  

I’dlike this to be my last trip behind the generator for a while!!!

many thanks to all

Porter McRoberts 
S/V IBIS A54-152 
Tahiti. 


Porter McRoberts
 

Gary et all I’ve read this thread a bunch and it is super helpful. Thanks for all your insights, and others. 

I’ve removed our cat pump several times in the past week and it’s a real bear. Issue: leaking at high pressure from somewhere around the head.

I’ve taken our 160 to a cat repair place here in Tahiti, thinking I found the leak and needed a new head. Long story short, they found a small hole in the brass elbow going up to the blue stabilization bulb. They think that’s the issue. I am skeptical. Since install and removal is several hours and horrible on the back I’d like to know if anyone knows what pressure the pump is rated for, and also what peak pressure I can reasonably expect  to see when running the pump. It seems like 60-65 bar would be that number, aiming for 56-58  

The guys at the shop pressure tested it to 30 bar with no leaks. I am asking them to retest to 60. They say that’s the maximum the pump is rated to. Is that true?  

What Bar is the low end of the green zone, and the high end of the green zone, assuming my guage is accurate, which I suspend mine not to be (we make 200+l/hr still well below the end of the green zone)?  

I’dlike this to be my last trip behind the generator for a while!!!

many thanks to all

Porter McRoberts 
S/V IBIS A54-152 
Tahiti. 


seagasm
 

Your a Champion Gary, Thank you for your reply.

Kind Regards
Barry Ferguson

Tradewinds III SM171

On 27/07/19 08:48, Gary Silver via Groups.Io wrote:
Hi Barry:

I used a timer nearly identical to this:   https://www.amazon.com/ustyle-Digital-Programmable-Precision-Anti-Interference/dp/B07TC9Z45J/ref=sr_1_7?keywords=24+volt+fish+feeder+timer&qid=1564180095&s=gateway&sr=8-7 

I believe mine is just a slightly older version.   I wired it's output to a second "ganged" 24 volt relay just to make sure I didn't overload or shorten the life of the contacts of the relay in this timer.  The coil of the second relay is wired such that when the timer calls for flushing (i.e. the timer closes its "NO" (normally open) contact, it energizes the more robust relay coil.  The second relays contacts are wired into the fresh water pressurization CB (circuit breaker)  wiring.  When I leave the boat, I switch the timer from the "run" (i.e. always on) position to the timer position then move the valve in the engine room to the flush position.  Thus when flush is called for the timer, energizes the second "ganged" relay, turns on the fresh water pump that runs for the programmed length of time (in my case 2 minutes every other day).  My system goes thru about 200 liters of H20 in 6 months on the hard using this schedule.  Others may vary based on the pump etc.  I just put a bucket where the flush water comes out on the port side of the boat, ran the program and measured the through-put of the water.  The only down side is that when on the boat and the timer is set to the run position, the ganged really is continuously energized (using a small amount of electricity) and you have to leave the main battery switches on to provide 24 Vdc power to the timer/relay circuity.  Mine has been running perfectly for about 11-12 years now.

Sincerely, 

Gary S. Silver
s/v Liahona    Amel SM 2000 #335
On the hard in Puerto Del Rey - Puerto Rico



Gary Silver
 

Hi Barry:

I used a timer nearly identical to this:   https://www.amazon.com/ustyle-Digital-Programmable-Precision-Anti-Interference/dp/B07TC9Z45J/ref=sr_1_7?keywords=24+volt+fish+feeder+timer&qid=1564180095&s=gateway&sr=8-7 

I believe mine is just a slightly older version.   I wired it's output to a second "ganged" 24 volt relay just to make sure I didn't overload or shorten the life of the contacts of the relay in this timer.  The coil of the second relay is wired such that when the timer calls for flushing (i.e. the timer closes its "NO" (normally open) contact, it energizes the more robust relay coil.  The second relays contacts are wired into the fresh water pressurization CB (circuit breaker)  wiring.  When I leave the boat, I switch the timer from the "run" (i.e. always on) position to the timer position then move the valve in the engine room to the flush position.  Thus when flush is called for the timer, energizes the second "ganged" relay, turns on the fresh water pump that runs for the programmed length of time (in my case 2 minutes every other day).  My system goes thru about 200 liters of H20 in 6 months on the hard using this schedule.  Others may vary based on the pump etc.  I just put a bucket where the flush water comes out on the port side of the boat, ran the program and measured the through-put of the water.  The only down side is that when on the boat and the timer is set to the run position, the ganged really is continuously energized (using a small amount of electricity) and you have to leave the main battery switches on to provide 24 Vdc power to the timer/relay circuity.  Mine has been running perfectly for about 11-12 years now.

Sincerely, 

Gary S. Silver
s/v Liahona    Amel SM 2000 #335
On the hard in Puerto Del Rey - Puerto Rico


seagasm
 

While we are on the subject of water makers, I would like to add a timer to ours for flushing. Who of you have used a timer and what/where to purchase from. I would assume here that it would be a 24volt unit setup so any available suggestions is appreciated.

Kind Regards
Barry Ferguson

Tradewinds III SM 171

On 27/07/19 02:04, Thomas Peacock wrote:
Thanks to everyone who responded. I can’t say enough about this group!

Some of the suggestions spurred me on to further research, down many rabbit holes. I’d like to give a synopsis of what I learned, read on only if interested, obviously. 

It was reassuring to find out that the 280 TDS is within a very reasonable range. I am going to clean the membranes, 2% citric acid solution for acid, and 2% sodium metasilicate for the alkaline. I’ll see if that buffs up the TDS at all.

Indeed, the World Health Organization, and many governmental agencies has standards for TDS in drinking water, with a spectrum of acceptability, generally over 1,000 being unacceptable, but less than 500 as desirable.

However, not all TDS are created equal. TDS is generally anions, cations, and organic molecules. They may occur due to leaching from the ground water table, or agricultural runoff. Where I live (northeastern US), many homes with wells have high TDS due to the wells being in limestone and other similar rock formations. The usual problem from high TDS here is “hard water”, due to excessive calcium and magnesium. This can cause buildup of deposits in plumbing, and poor washing with detergents and soaps.

In other parts of the world, high TDS may be due to agricultural runoff, and include phosphates and organic molecules.

For our purposes on a boat, TDS reflects residual anions and cations from the sea water. In this case, it is almost exclusively sodium and chloride. 

So, high TDS not associated with water makers is usually calcium, magnesium (plus or minus organics); indeed, San Pellegrino water, a highly regarded drinking water from Italy, has 1,100 TDS (mostly calcium, magnesium, and sulfate), unacceptable by some standards, but tasty to many people. 

High TDS on a boat with a RO water maker implies poorly functioning membranes, will be mostly sodium and chloride, and, for many people, becomes unpalatable above 400 TDS. There is not a USA EPA standard for sodium in drinking water, but the EPA does recommend not exceeding 250 mg per liter of chloride. This standard is predominantly an “aesthetic” one, and reflects the salty taste that a level of 250 or above will impart to the water. As per Dessalator’s specs, RO water with a TDS of 250 has 183 mg per liter of chloride. The conclusion that I would draw from this is a TDS of about 350 or above would exceed the EPA’s recommendation. Again, this is predominantly a taste concern, but there are some potential health effects. People with heart or kidney problems may not tolerate it well and retain fluid as the TDS rises.

Tom Peacock
SM #240 Aletes
Chesapeake Bay, USA



On Jul 23, 2019, at 1:05 PM, Thomas Peacock via Groups.Io <peacock8491@...> wrote:

I’m hoping to get a few tips on our water maker. We have a LaRochelle installed Dessalator, I believe a D60, SM 240, 24 volts only. We have used it only sporadically. 
I put new membranes in 2 years ago. I am trying to be sure it works properly, we are in the Chesapeake Bay, which is only brackish water so we don’t use it there. Going to Martinique this fall. 
The Dessalator manual at one point says we should have 250 TDS, at another it says 500, which certainly tastes brackish. 
At 40 bar we get 270, at 60 bar about 330, which then goes down to 280 after about 5 minutes. We get 0.75 liters/minute. 
Is this acceptable performance? I am more concerned about the TDS than the rate. I would like to clean the membranes as suggested by Dessalator, all they say is “cleaning solution”. Is this the same as the pickling compound, sodium metabisulfite? 
Thanks as always for everyone’s insights. 
Tom Peacock
SM 240 Aletes
Chesapeake Bay








Thomas Peacock
 

Thanks to everyone who responded. I can’t say enough about this group!

Some of the suggestions spurred me on to further research, down many rabbit holes. I’d like to give a synopsis of what I learned, read on only if interested, obviously.

It was reassuring to find out that the 280 TDS is within a very reasonable range. I am going to clean the membranes, 2% citric acid solution for acid, and 2% sodium metasilicate for the alkaline. I’ll see if that buffs up the TDS at all.

Indeed, the World Health Organization, and many governmental agencies has standards for TDS in drinking water, with a spectrum of acceptability, generally over 1,000 being unacceptable, but less than 500 as desirable.

However, not all TDS are created equal. TDS is generally anions, cations, and organic molecules. They may occur due to leaching from the ground water table, or agricultural runoff. Where I live (northeastern US), many homes with wells have high TDS due to the wells being in limestone and other similar rock formations. The usual problem from high TDS here is “hard water”, due to excessive calcium and magnesium. This can cause buildup of deposits in plumbing, and poor washing with detergents and soaps.

In other parts of the world, high TDS may be due to agricultural runoff, and include phosphates and organic molecules.

For our purposes on a boat, TDS reflects residual anions and cations from the sea water. In this case, it is almost exclusively sodium and chloride.

So, high TDS not associated with water makers is usually calcium, magnesium (plus or minus organics); indeed, San Pellegrino water, a highly regarded drinking water from Italy, has 1,100 TDS (mostly calcium, magnesium, and sulfate), unacceptable by some standards, but tasty to many people.

High TDS on a boat with a RO water maker implies poorly functioning membranes, will be mostly sodium and chloride, and, for many people, becomes unpalatable above 400 TDS. There is not a USA EPA standard for sodium in drinking water, but the EPA does recommend not exceeding 250 mg per liter of chloride. This standard is predominantly an “aesthetic” one, and reflects the salty taste that a level of 250 or above will impart to the water. As per Dessalator’s specs, RO water with a TDS of 250 has 183 mg per liter of chloride. The conclusion that I would draw from this is a TDS of about 350 or above would exceed the EPA’s recommendation. Again, this is predominantly a taste concern, but there are some potential health effects. People with heart or kidney problems may not tolerate it well and retain fluid as the TDS rises.

Tom Peacock
SM #240 Aletes
Chesapeake Bay, USA

On Jul 23, 2019, at 1:05 PM, Thomas Peacock via Groups.Io <peacock8491=gmail.com@groups.io> wrote:

I’m hoping to get a few tips on our water maker. We have a LaRochelle installed Dessalator, I believe a D60, SM 240, 24 volts only. We have used it only sporadically.
I put new membranes in 2 years ago. I am trying to be sure it works properly, we are in the Chesapeake Bay, which is only brackish water so we don’t use it there. Going to Martinique this fall.
The Dessalator manual at one point says we should have 250 TDS, at another it says 500, which certainly tastes brackish.
At 40 bar we get 270, at 60 bar about 330, which then goes down to 280 after about 5 minutes. We get 0.75 liters/minute.
Is this acceptable performance? I am more concerned about the TDS than the rate. I would like to clean the membranes as suggested by Dessalator, all they say is “cleaning solution”. Is this the same as the pickling compound, sodium metabisulfite?
Thanks as always for everyone’s insights.
Tom Peacock
SM 240 Aletes
Chesapeake Bay



Mark McGovern
 

Craig,

Your summation lines up perfectly with all of my reading on the subject of Reverse Osmosis.  The Mid-Chesapeake Bay area will be our cruising grounds for the next few years so my watermaker will only see brackish water for quite some time.  I had read in numerous places online that I would "damage my membrane" if I ran it in the Chesapeake but research from source data shows otherwise.  The Filmtec SW30 RO membrane used in our system is clearly NOT the ideal membrane for the Chesapeake Bay, but it does not seem that I will do any harm to it if I operate it at lower pressures like you mention.  For any other "geeks" interested in RO information here is a link to the 197 page technical manual from Dupont Filmtec, maker of the RO membrane:  https://www.dupont.com/content/dam/Dupont2.0/Products/water/literature/609-00071.pdf  Riveting reading for sure! ;)

--
Mark McGovern
SM #440 Cara
Deale, MD USA


Craig Briggs
 

Regarding brackish water operation, that's one of those topics that's been burdened with a lot of myth and misunderstanding in the cruising community.  It is absolutely OK to run your water maker in brackish or even totally fresh water.  It will not damage the membrane as long as you do not exceed the membrane's rated product flow.

Think of it this way - the "green" zone is the pressure at which the membrane is passing it's rated flow of product water.  If that is exceeded the membrane will start to tear apart and fail. Our pressure gauges happen to show a "green" zone for sea water and that's in the range of 800-850 psi / 55-58 bars which gives you your rated output for sea water. However, the "green" zone for water of lower salinity is at a lower pressure. So, for example, the fresh water "green zone" is only about 150-200 psi / 10-14 bars for the same rated output, and the brackish water "green zone" will be somewhere in between, depending on its salinity.

The proper procedure for brackish or fresh water, then, is to bring the pressure up slowly until you are getting the rated flow of product water.  Don't crank it up to the sea-water "green" zone or, yes, you will damage the membrane. And running sea water at 950 psi (65 bar) may shorten the life of your membranes, although that may be OK in the Med with it's very high salinity vs., say, the open Pacific or Atlantic as long as the product flow is correct.

I'd guess the idea that running your water maker in brackish water will damage the membrane probably stems from having our pressure gauges show a sea-water "green zone" - some people have cranked the pressure up to that "green zone" in brackish water and damaged their membranes and hence the misinformation starts to circulate. 

Bottom line though - feel free to sail up the Guadiana or lock into Loch Ness or sail the Great Lakes - you can make water in any salinity - just don't crank the pressure up to the sea water green zone.

Cheers,
Craig, SN68 Sangaris


Mohammad Shirloo
 

Hi All;

We have the 150 l/hr Dessalator. Martin Dee Jong at Dessalator has been our main go to person when we’ve had any issues with our Dessalator. He has always been extremely knowledgeable and helpful and his information has always been spot on. I believe he has the position of director now for Dessalator in a couple of countries.

According to Martin there is no advantage in running the system at low pressures. In fact he advised that it should always be run at max pressure in the green simply because we will produce more water without any downside.

He also advises that as long as the system in run regularly, at least once a week, there is no need for fresh water flush. For wintering he advised us to follow their system of sterilization for up to 6 months.

We have followed his advise with good results so far. We have about 470 hours on the water maker which is now 11 years old on the original membranes. We always get production rates of 150-180 l/hr depending mainly on the water temperature. Our TDS runs in the 250 range all the time. We do not use any water other than Dessalator water on board, so the water maker gets used at least every other when we are on board, which is about 5-6 months every year.

Respectfully;


Mohammad & Aty
B&B Kokomo
Amel 54#099

On Jul 24, 2019, at 4:21 PM, Ryan Meador via Groups.Io <ryan.d.meador@...> wrote:

Hi Tom,

Great meeting you last week.  I believe we have the same watermaker you do (Iteration is hull 233).  We see almost exactly the same production rate that you do.  I believe we see similar TDS as well, but we do not have a meter; I think the folks in Martinique told me it was about 250 when they rebuilt it last winter.  We were instructed to run it at 55-60 bar, despite the green zone on the gauge being from 60-65 bar.  They said it shortens the membrane life to run it at higher pressure.

While we're on the subject, I saw this article just a few days ago about how the neighboring town of Cambridge, MA has a TDS of 469 in their public water supply!

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA


On Tue, Jul 23, 2019 at 6:34 PM Craig Briggs via Groups.Io <sangaris=aol.com@groups.io> wrote:
Bill et al,
World Health Organization to the rescue; but anything <500 ppm is good.
"TDS is a measure of Total Dissolved Solids in Water which comprise of inorganic salts, principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates, and small amounts of organic matter that are dissolved in water. TDS in drinking-water originates from natural sources, sewage, urban runoff, and industrial wastewater. Concentrations of TDS in water vary considerably in different geological regions owing to differences in the solubility of minerals.

According to WHO report on Drinking water standards, NO health-based guideline value is proposed for TDS in Drinking Water which essentially means that human body can ingest any amount of TDS in water without any health impact. Now the question is …Why high TDS is considered bad in Drinking Water?

The simple reason is the palatability or taste! Yes, you heard it right. High levels of TDS in drinking-water may have a certain objectionable taste because of salts. The palatability of water with a TDS level of less than 600 mg/liter is generally considered to be good; drinking-water becomes significantly unpalatable at TDS levels greater than 1200 mg/liter. Also, TDS may be high because of certain chemicals which are harmful and hence purification is required to eradicate them. However, this is not a concern in naturally available water. Thus, we can drink the water of any TDS level if it is devoid of harmful pathogens, chemical, and other unacceptable impurities.Hence…high TDS does not lead to any health problem. The presence of high levels of TDS may also be objectionable because of excessive scaling in water pipes, heaters, boilers, and household appliances.

Alternatively, water with extremely low concentrations of TDS may also be unacceptable because of its flat, insipid taste.Most purification techniques such as filtration, membrane processing or sedimentation aim to eliminate the impurities that form high TDS. Water is treated or purified to maintain palatability as well as purity in terms of microbial and chemical composition. It has nothing to do with TDS or mineral content. Purifiers in the market with TDS modulator or a Mineral Booster are just for marketing promotion for naïve customers and do not have any rationale behind it.

To know more about TDS in drinking water, go through the following research published by WHO.WHO Guidelines for drinking-water quality -2008

http://www.who.int/water_sanitat...


Gary Silver
 

Hi Tom and All:

A few notes on desalination of seawater and my experience with my Dessalator 160 l/hr over the last 18 years of use:
 
For the following reason I measure EC (electrical conductivity)  not TDS for measuring my product water;

"EC stands for Electrical Conductivity and is measured micro-siemens per centimeter. TDS stands for Total Dissolved Solids and is measured in PPM or parts per million. TDS is acquired by taking the EC value and performing a calculation to determine the TDS value. Because TDS is actually a calculation it is really only a guess at what the nutrient concentration is. On top of that, there are three different conversion factors to determine TDS and different manufacturers use different conversion factors. In other words you could test the same solution with two different meters and get two totally different readings. But the EC is read the same by all meters the only difference is the conversion factor."

I take this to mean the EC is a primary measurement whereas TDS is a secondary calculated value (based on a formula).  That said, TDS meters are probably "pretty close".  I love the quote from the WHO that shows that there isn't a hard and fast number for TDS, it is a range and various palates will taste water in different ways. 

My experience : Water makers love to be used.  Lack of use is probably the most common cause of membrane failure.  Frequent (daily or every other day) use will prolong their life.  

I have never quite understood why operation in brackish water is damaging but I have heard that opinion often enough to believe that it is so. 

Since I monitor EC continuously I can speak to the trends associated with water maker use: 

1. Upon startup of my 160l/hr Dessalator water maker, the EC will start about where it left off when it was shut down (usually about 400 microSeimens/cm), this is due to the last produced product water being at the EC sensor,
2.  Within seconds the ED will rise to over 2,000 microsiemens (max recording range of my EC monitor), I have speculated on why this rises (osmosis vs reverse-osmosis taking place within the membrane capsule during the shut down period)
3.  Then over a period of about 2 minutes it will gradually fall to about 600 mS, at which point I will start to "Save" the product water.  I have a manual "Save / Discard" switch and utilize that to determine when to save product water.
4.  Then EC will fall continuously during production (the longer the water maker runs the lower it goes).    
5.  The higher the pressure that I run the water maker (up to 65 Bar, top of the green), the lower the EC / better the EC.  At bottom of the green the EC will usually be about 50-100 microSiemens/cm higher than when run at the top of the green.  

You do no favors to your water maker or product water by running it below the green arc.  I routinely run my membranes at 65 bar and I am only only my 3rd set of membranes in 18 years (NOTE: I use my boat only 3 months out of the year and have a automatic timer that flushes the membranes with carbon block filtered product water for 2 minutes every 48 hrs when I am not aboard the boat, so my experience probably isn't typical for a cruising sailboat).

So many good questions around the water maker.   Can't speak to "cleaning" the members as I have never found the need to do that. 

One last point: don't use sodium metabisulate to pickle your water maker unless you absolutely have no other option.  If you do use it, only use it at the lowest possible effect concentration and for the shortest period of time possible.  It is corrosive and can damage metal parts in you water maker (hence the reason I have a fresh water flush system and haven't pickled in in 13 years).

All the best to my fellow Amel owners who, like me, are on a never ending journey of learning.

Gary S. Silver, M.D.
s/v Liahona
Amel SM 2000  Hull #335
On the hard at Puerto Del Rey Marina, Puerto Rico


Ryan Meador
 

Hi Tom,

Great meeting you last week.  I believe we have the same watermaker you do (Iteration is hull 233).  We see almost exactly the same production rate that you do.  I believe we see similar TDS as well, but we do not have a meter; I think the folks in Martinique told me it was about 250 when they rebuilt it last winter.  We were instructed to run it at 55-60 bar, despite the green zone on the gauge being from 60-65 bar.  They said it shortens the membrane life to run it at higher pressure.

While we're on the subject, I saw this article just a few days ago about how the neighboring town of Cambridge, MA has a TDS of 469 in their public water supply!

Ryan and Kelly
SM 233 Iteration
Boston, MA, USA


On Tue, Jul 23, 2019 at 6:34 PM Craig Briggs via Groups.Io <sangaris=aol.com@groups.io> wrote:
Bill et al,
World Health Organization to the rescue; but anything <500 ppm is good.
"TDS is a measure of Total Dissolved Solids in Water which comprise of inorganic salts, principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates, and small amounts of organic matter that are dissolved in water. TDS in drinking-water originates from natural sources, sewage, urban runoff, and industrial wastewater. Concentrations of TDS in water vary considerably in different geological regions owing to differences in the solubility of minerals.

According to WHO report on Drinking water standards, NO health-based guideline value is proposed for TDS in Drinking Water which essentially means that human body can ingest any amount of TDS in water without any health impact. Now the question is …Why high TDS is considered bad in Drinking Water?

The simple reason is the palatability or taste! Yes, you heard it right. High levels of TDS in drinking-water may have a certain objectionable taste because of salts. The palatability of water with a TDS level of less than 600 mg/liter is generally considered to be good; drinking-water becomes significantly unpalatable at TDS levels greater than 1200 mg/liter. Also, TDS may be high because of certain chemicals which are harmful and hence purification is required to eradicate them. However, this is not a concern in naturally available water. Thus, we can drink the water of any TDS level if it is devoid of harmful pathogens, chemical, and other unacceptable impurities.Hence…high TDS does not lead to any health problem. The presence of high levels of TDS may also be objectionable because of excessive scaling in water pipes, heaters, boilers, and household appliances.

Alternatively, water with extremely low concentrations of TDS may also be unacceptable because of its flat, insipid taste.Most purification techniques such as filtration, membrane processing or sedimentation aim to eliminate the impurities that form high TDS. Water is treated or purified to maintain palatability as well as purity in terms of microbial and chemical composition. It has nothing to do with TDS or mineral content. Purifiers in the market with TDS modulator or a Mineral Booster are just for marketing promotion for naïve customers and do not have any rationale behind it.

To know more about TDS in drinking water, go through the following research published by WHO.WHO Guidelines for drinking-water quality -2008

http://www.who.int/water_sanitat...


Craig Briggs
 

Bill et al,
World Health Organization to the rescue; but anything <500 ppm is good.
"TDS is a measure of Total Dissolved Solids in Water which comprise of inorganic salts, principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates, and small amounts of organic matter that are dissolved in water. TDS in drinking-water originates from natural sources, sewage, urban runoff, and industrial wastewater. Concentrations of TDS in water vary considerably in different geological regions owing to differences in the solubility of minerals.

According to WHO report on Drinking water standards, NO health-based guideline value is proposed for TDS in Drinking Water which essentially means that human body can ingest any amount of TDS in water without any health impact. Now the question is …Why high TDS is considered bad in Drinking Water?

The simple reason is the palatability or taste! Yes, you heard it right. High levels of TDS in drinking-water may have a certain objectionable taste because of salts. The palatability of water with a TDS level of less than 600 mg/liter is generally considered to be good; drinking-water becomes significantly unpalatable at TDS levels greater than 1200 mg/liter. Also, TDS may be high because of certain chemicals which are harmful and hence purification is required to eradicate them. However, this is not a concern in naturally available water. Thus, we can drink the water of any TDS level if it is devoid of harmful pathogens, chemical, and other unacceptable impurities.Hence…high TDS does not lead to any health problem. The presence of high levels of TDS may also be objectionable because of excessive scaling in water pipes, heaters, boilers, and household appliances.

Alternatively, water with extremely low concentrations of TDS may also be unacceptable because of its flat, insipid taste.Most purification techniques such as filtration, membrane processing or sedimentation aim to eliminate the impurities that form high TDS. Water is treated or purified to maintain palatability as well as purity in terms of microbial and chemical composition. It has nothing to do with TDS or mineral content. Purifiers in the market with TDS modulator or a Mineral Booster are just for marketing promotion for naïve customers and do not have any rationale behind it.

To know more about TDS in drinking water, go through the following research published by WHO.WHO Guidelines for drinking-water quality -2008

http://www.who.int/water_sanitat...


Mark McGovern
 
Edited

Tom,

250 ppm is what you are looking for as far as TDS goes. The EPA’s recommended maximum level of TDS in water is 500 ppm.  Note, it's not a limit, just a recommendation.  The 500 number you saw may have been for Conductivity (proxy for Salinity) which is measure in microSiemens/cm (µS/cm).  You want that between 200 and 800 and I think Dessalator claims 250 TDS and 550 Conductivity in their marketing material. 

I picked up this kit from Amazon to test it:  https://www.amazon.com/gp/product/B077SQTKH4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

I have no idea how accurate it is, but it gives me reasonable results for tap water, distilled water, Chesapeake Bay water and watermaker water so it appears to be accurate enough.
 
--
Mark McGovern
SM #440 Cara
Deale, MD USA