Watermaker - Experiences life expectancy of membranes

[Dos]

Hello everybody,

hope you are all well!

I am faced with the decision to equip a 12V or 230V watermaker in the approx. 60L/h range (+/-) for my Contest 41.

Knowing that the life expectancy of 230V systems obviously seems to be significantly better, these also usually have a power consumption that is more than twice as high. I want to try to do without a generator (have 800Wp solar and a silentwind), so that I inevitably get out of the 12V watermaker first.

Hence the question for you about your practical experience with the service life of the membranes (12V and 230V systems). Can you name a few of your experiences here? Of course, this is very dependent on the sea area (for me mainly the tropical barefoot route Atlantic + Pacific) and the frequency of use, but currently I have not been able to find any empirical values.

Would be very grateful for your hopefully numerous replies :-)

Best regards,
Dosheimer

[Takamoana]

We have a Dessalator, 12V, 60 litres/Hr with around 1400 hours on the clock. Have had 1 membrane fail around 5 years ago and replaced the pair ( from memory around US$150 each) Apart from a circuit card issue early on, which was replaced under warranty, the unit has been trouble free. We have 1080 Watts of solar which is our main power source.

[Paul L]

Not sure why you are focusing on membrane life. If you get a quality AC or DC unit, use it often and do normal maintenance on it you will get many years out of a membrane, say 3 to 6, from either one. Why should this be a major criteria?

[Dos]

Hi Paul L, thanks for your response.

It only would be a significant criteria for me in case the replacement frequency would be very high. It would be a cost criteria in that case and has to do with availability in remote areas and therefore spare part reserves on board etc.

I would like to find out if such data is based on producers marketing statements or from real cruiser lives experience confirmed by our cruising sailor community.

You are speaking about 3-6 years of life span. Is this your personal experience with your own watermaker so far?

[Dos]

It would be interesting for me to see how significant the difference in the membrane life spans are at 230V systems compared to 12V systems - all based on real experiences and not on producers marketing.

Do we i.e. see a only 10% better or already 10x the life span (because of the much higher flow rate) or would it be maybe not relevant at all as even the 12V systems have life spans of many years.

I would like to get an impression on that from your postings.
Thank you!

[GordMay]

I don’t see any mechanism, whereby an R/O membrane could know [or care] at what voltage [or AC vs DC], the pump is providing pressurised water to them.

[Paul L]

Originally Posted by Dos

Hi Paul L, thanks for your response.

It only would be a significant criteria for me in case the replacement frequency would be very high. It would be a cost criteria in that case and has to do with availability in remote areas and therefore spare part reserves on board etc.

I would like to find out if such data is based on producers marketing statements or from real cruiser lives experience confirmed by our cruising sailor community.

You are speaking about 3-6 years of life span. Is this your personal experience with your own watermaker so far?

Yes, this is personal experience with two different brands of 12v watermakers on a full time cruising boat.

[Dos]

Originally Posted by GordMay

I don’t see any mechanism, whereby an R/O membrane could know [or care] at what voltage [or AC vs DC], the pump is providing pressurised water to them.

That is an original comment from the managing director of Aquatec watermakers in this context (translated from German into English from me):

["...It is actually the case that the AC systems have more energy requirements. This is due to the fact that the pump output is higher in order to achieve a higher flow over the membrane. This improves the quality of the product water and increases the service life of the membrane. The more energy I invest in the system, the longer the service life and the better the product water I achieve. A 12V system is always a compromise between consumption and yield..."]

Maybe with this you now will be able to understand my interest in the practical service time / life span of a 12V membrane in cruising sailor conditions based on your real life experiences.

I had calculated 118% more power requirement of a 230V system compared to a 12V system with same fresh water output per hour.

[Paul L]

The AC uses more power for more reasons than higher flow rates.
Have you actually looked at the power consumption per gallon (or liter) between an AC system and say a Spectra DC system? A Spectra Cape Horn is 16 Watts/1 gal., 4.2 Watts/1 liter. An AC system will use about twice the power.

[s/v Thea]

I got about 6 years out of my fist set of membranes. Home built 12v 1hp system with 2 x 40” membranes. Used 3-6 mo/yr, pickled the rest of the time

[JasonS]

As long as you can and do properly backflush your membrane as recommended you should get many years of life from your membrane.

[meirriba]

You may want to look at the Dessalator dual voltage watermaker. Works both on DC or AC.

[DMCantor]

We have a 12v Spectra, 13gph. We cruise about 5 months/year, and is pickled the rest of the time. Our membrane is 11 years old, and makes excellent-quality water with no degradation in performance whatsoever.


The 12v energy-recovery watermakers are drastically more energy efficient than all others. If you are running off solar, it is really the only choice.


With two of us on board, we meet all our water needs running the system for 3 hours or so every 4 days. We by no means scrimp on water consumption (frequent showers, on-board washing machine, etc.) I don't really understand the need for high output watermakers.

[PirateGuy]

Originally Posted by DMCantor

We have a 12v Spectra, 13gph. We cruise about 5 months/year, and is pickled the rest of the time. Our membrane is 11 years old, and makes excellent-quality water with no degradation in performance whatsoever.


The 12v energy-recovery watermakers are drastically more energy efficient than all others. If you are running off solar, it is really the only choice.


With two of us on board, we meet all our water needs running the system for 3 hours or so every 4 days. We by no means scrimp on water consumption (frequent showers, on-board washing machine, etc.) I don't really understand the need for high output watermakers.

What’s the point of high output water makers? What’s the point of passenger vehicles with 500hp engines? Or 5 bedroom/6 bathroom homes for 2 people for that matter?

Just how do you suggest men strut their junk (or women their silicone) if the world didn’t have conspicuous consumption?

[zstine]

Originally Posted by DMCantor

. . . . .I don't really understand the need for high output watermakers.

I agree with you on the assumption you have a 12V system powered with Solar. But if you have to run a generator to power your RO pumps, then high output minimizes the run time of the generator... personally, I don't understand why anyone would want a generator over solar if they had to choose one, but that's a separate topic.

For the OP, you may want to watch some of SV Seeker YouTube on RO. He addresses flushing, flow rate and life of elements.