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11-18-2009, 08:57 AM
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#1
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Ensign
Join Date: May 2009
Posts: 6
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Does anyone have any information on the chemical composition of the materials that are commonly used to clean watermakers? They come in 2 types - acid based powders that will remove mineral scale (like calcium carbonate) - and alkali based powders that will remove organic slime.
I have just installed a Village NF450 watermaker- a 220v AC system - and am collecting the operating materials that I need to run it. I have just purchased the standard Village cleaners from their local distributor in New Zealand (they come in 600 gram plastic containers) and got charged US$135 for the 2 packets! Someone is making a lot of money on this stuff!!!
So for obvious reasons I need to find some generic alternatives. I have used mild hydrochloric acid (also known as spirits of salts or muriatic acid) to remove mineral scale from toilet systems, so it may be that this would do a similar job on a watermaker?
Dishwashing powder is a slightly alkaline cleaner - perhaps that would be suitable as the alkaline cleaner?
The specs also call for special preservative for pickling the membrane when it isnt used for a period- but thankfully I have determined that this preservative is just sodium metabisulfate, a common food preservative, and is available for about US$5 for a 600 gm packet!!
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11-23-2009, 02:15 PM
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#2
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Ensign
Join Date: Sep 2008
Home Port: Hollywood
Vessel Name: Poerava
Posts: 10
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Quote:
Originally Posted by RichardJ
Does anyone have any information on the chemical composition of the materials that are commonly used to clean watermakers? They come in 2 types - acid based powders that will remove mineral scale (like calcium carbonate) - and alkali based powders that will remove organic slime.
I have just installed a Village NF450 watermaker- a 220v AC system - and am collecting the operating materials that I need to run it. I have just purchased the standard Village cleaners from their local distributor in New Zealand (they come in 600 gram plastic containers) and got charged US$135 for the 2 packets! Someone is making a lot of money on this stuff!!!
So for obvious reasons I need to find some generic alternatives. I have used mild hydrochloric acid (also known as spirits of salts or muriatic acid) to remove mineral scale from toilet systems, so it may be that this would do a similar job on a watermaker?
Dishwashing powder is a slightly alkaline cleaner - perhaps that would be suitable as the alkaline cleaner?
The specs also call for special preservative for pickling the membrane when it isnt used for a period- but thankfully I have determined that this preservative is just sodium metabisulfate, a common food preservative, and is available for about US$5 for a 600 gm packet!!
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First, why have you determined you need the cleaning chemicals? My experiance is that by the time most people realize the membranes need cleaning it is too late and a watse of time and money. Not always but most of the time. Sodium metabisulfate is used in most watermakers (except Spectras) to pickle the unit. P ropylene glycol is better.
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11-23-2009, 04:35 PM
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#3
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Admiral
Join Date: Jul 2004
Posts: 2,098
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Richard,
I can't find anything on the Internet after a quick search, and rather than do a longer search, I have a suggestion.
The cleaning chemicals you received, if they were packaged in the USA, should have some notation on them referencing a US regulation number. In my experience it will take some perseverance on your part to get to the right document, but I have usually found what I was looking for.
There should be something on the order of "EPA Reg. No. xxxx-xxx-xxxxx""
and/or "EPA Est. No. xxxxx-?????"
I searched numbers as above for a bacteriostat I had in our basement. Putting in "EPA" or otherwise didn't get me anywhere, but just putting in the number, as in the format above/on the label, got me results. The first two I checked weren't the right results, but in the past it took some work and some ingenuity in the search to finally get to the EPA product analysis submission. (something like that, anyway), which gave chemical formulas and/or chemical names.
I hope this is helpful.
J
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12-12-2009, 08:04 AM
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#4
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Ensign
Join Date: May 2009
Posts: 6
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Thanks for those tips. Unfortunately the labels did not make any reference to an EPA number so I couldnt take that any further.
However I bumped into a fellow sailor recently who had been looking at the same issue. He had contacted the maker of his watermaker and was given the generic names of the cleaners straight up. He was told that the acid cleaner is actually citric acid and the alkaline cleaner is sodium metasilicate - both of which are reasonable common chemicals. The dilution rate in both cases was a 2% mix - ie 200gm into 10 kg of water. I also note the comment about whether cleaning is likely to be needed - and it ties into what I have been hearing as well.
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12-12-2009, 11:29 AM
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#5
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Admiral
Join Date: Jul 2004
Posts: 2,098
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Watermakers are not something that I have much knowledge of, we had a very small one that we wound up not using because the work to maintain it was more than the water we were getting from it. We did clean is regularly as instructed, and we "pickled" it whenever it wasn't used for any length of time.
That said, our only other knowledge is of a friend's watermaker, which made lots and lots of water - 50 (or 30) gallons per hour. They used desalinated fresh water for everything on the boat, including regular deck washdowns. They had left for the S. Pacific and French Polynesia when they realized that they were supposed to clean the membrane. They put it off because they didn't have a large enough container to hold the chemicals and water. The watermaker about a week or two into their passage stopped working and they had to conserve water until they reached Tahiti. That was difficult for the 5 people on board since they had never given a thought to water conservation before. I believe, if I remember correctly, that they had to buy a new membrane, less than a year into their cruising.
With no first-hand knowledge, I'm just passing this on to you, though.
J
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12-12-2009, 09:52 PM
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#6
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Rear Admiral
Join Date: Feb 2006
Posts: 437
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I'm certainly no expert, but... I am lazy.
I've worked on a number of boats with watermakers over the years and I installed a "Frankenstein" model in Gallivanter made mostly from discarded parts found in dumpsters around large marinas as we sailed from St Thomas down to Trinidad... where we purchased new membranes & pressure housings from EchoTek, which brought the system up to making 50 gal per hour.
But what I'm getting at... and I'm sure there'll be many who disagree... but I have NEVER "pickled" or chemically cleaned any of the watermakers that have been on any of the boats I've worked on or the one we now own.
The only off-season maintenance I've ever done is simply run the system periodically in order to prevent the membranes from drying out. If so equiped, I'd back flush the membranes with product water from the tank... but in most cases I just run the system for a half hour or so every week or two during the off season. While the boat is active, the watermaker is used enough to keep the membranes wet... and happy.
In our case, living aboard Gallivanter fulltime, we make water about once a week to fill the tanks. We need to run the engine at least that often just to give the batteries a good charge. A good charge takes about four to six hours to fully charge the bank... and a by-product of recharging the batteries is a full tank of water for running our little washing machine AND two days' hot water for showers! Kinda like killing FOUR birds with one stone... one noisy day on the boat gives is full batteries, clean laundry, full water tanks and hot water for showers.
Yes - it's noisy but I guess that's the price we have to pay to live the way we do... and I don't need to be bothered with chemically maintaining our watermaker.
To Life!
Kirk
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12-15-2009, 01:43 AM
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#7
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Ensign
Join Date: Feb 2009
Posts: 25
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Sodium metasilicate pentahydrate for the alkali and sulphamic acid for the descalant. Use the alaki first at 50 grams per 4.5 litres water, circulate for 1/2 hour, stop circulation and let it soak for 1 hour, circulate for another 1/2 hour then flush out. Fill with acid at same dilution as alkali, circulate for 45 min - 1 hour then flush. Do not use soak for the acid.
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12-15-2009, 01:47 AM
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#8
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Ensign
Join Date: Feb 2009
Posts: 25
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Quote:
Originally Posted by Gallivanters
and I don't need to be bothered with chemically maintaining our watermaker.
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Chemical cleaning will increase the life of membranes and should be carried out regularly, intervals dependant on quality of feedwater and prefiltration. It will increase production and often improve product water quality.
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