Re: Membrane Tube end caps


 

One of the things that have not been mentioned in this Topic is the possible causes of the deterioration of some materials used for endcaps.

There is anecdotal evidence that points to Sodium Metabisulfite, the pickling chemical as being a cause, especially when it is mixed in a solution greater than recommended by Dessalator. IMPORTANTLY, the smaller watermakers (50-60 liter) have less than 1/3rd the internal volume that the larger watermakers (150-250), yet the recommended dosage is the same! This makes no sense to me. Additionally, there are some who believe if a small amount of pickling agent is good, more is better. BeBe (SM 387), with a D160 watermaker, had this "more is better" problem for the first 1.5 years of her life. She was cared for by an "experienced" guy in Tortola. He was one of those who believed, more is better. During his this time,  BeBe's owner only used BeBe 3 or 4 times for 2 weeks or less.  After each use, he had the caretaker pickle the watermaker. Within a few months of our ownership, the membranes needed replacing, and the white endcaps were deteriorated around the interconnect bobbin. When we bought BeBe, the watermaker had 34 hours on the meter, but the endcaps and the membranes needed replacing. I estimate that, except for a few weeks, the system was filled with a very high solution of Sodium Metabisulfite.

I replaced the white end caps with the "new" black end caps and had no issues for almost 11 years of ownership. During that ownership, I never used Sodium Metabisulfite. I replaced the membranes about every 3 years. I replaced them when the TDS neared 300ppm. This was my preference. Interestingly some Spectra watermakers have an auto-rejection system that rejects product water at 750ppm (default). Some watermaker manufacturers have said that any ppm that is under 1000ppm is safe. WHO states that 750ppm is safe, but recommends a daily intake limit at 500ppm. The efficiency of membranes, in terms of ppm changes with age. The slow creep of ppm will not be noticed. You should check ppm continuously.

Lastly, I have found Dessalaltor to be responsive to our needs. And, please remember this: "We encourage postings which will genuinely help Amel owners source needed parts and services. We encourage you to support the Amel brand and be respectful to the brand in your postings. Care should be taken to not post anything that could be considered offensive or derogatory regarding Amel, any Member, or Sponsor. Please refrain from political issues, rude, or inappropriate language. Please refrain from criticism of persons or businesses in which you may have experienced unsatisfactory results, because it would be one-sided, without the ability of the other side to respond."

BTW, Dessalator is the supplier of choice of many Super Yachts.


CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
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On Wed, Apr 22, 2020 at 7:41 AM Arno Luijten <arno.luijten@...> wrote:
Hi Danny,

I fully agree we should not dismiss the choices Amel made too easy. I think the choice Amel made with the Desalator watermaker was excellent. But like with everything in life it was also a compromise between pro's and con's.
Reality is that companies that make watermakers are up to some extent just assembling stuff that is in the market anyway. So the membranes are from DuPont, the HP pump is from Cat, etc, etc.
But fact remains there are some valid points of criticism to be expressed for the Desalator product. That does not imply that Amel is to blame. It just means that Desalator has room for improving the product.
Until now I did not find a cruiser perfectly happy with his or hers watermaker. These things are extremely sensitive to bad treatment and treating them well can be a drag after so much time.
From my point of view there are a few things Desalator could improve with very little cost. I appreciate they don't change the product every two years and forget about spareparts for the installed base, like many companies do, but there are some obvious thing they could improve like many Amel owners already did themselves.

Regards,

Arno Luijten
SV Luna,
A54-121

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