Re: Membrane Tube end caps
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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.
On Wed, Apr 22, 2020 at 7:41 AM Arno Luijten <arno.luijten@...> wrote: