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Old 02-03-2012, 17:45   #1
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Membrane Life Expectancy

I have a PUR80, but I am posing this as a more general question.

What is the life expectancy of well cared for watermaker membranes?

My first set went cruising for five years, getting used nearly daily. When I laid up the boat for five years I accepted that new membranes would part of getting out the next time. The second time out, with new membranes, again for five years, again nearly daily use, and always great water quality according to my TDS meter.

I've been tied to a dock now for 2.5 years, and won't get out till this Fall. I have run, and re-pickled every six month. The TDS reading, after running for two hours, each time has shown in the the normal range.

Should I budget for new membranes before I leave? It's nearly a boat unit to put in new ones, and I'd sure rather continue collecting that .75% interest on those precious cruising chips.

The boat only has a 40 gallon tank, so crossing oceans requires a functional watermaker or a radically different lifestyle than I prefer. I depart with full tanks and top them off daily. If the trusty WM failed I would immediately go on short rations.

I've read plenty of manufacturers recommendations. What I am looking for here is real world experience. Anybody out there with regularly used membranes that have gone ten years? Twenty?
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Old 02-03-2012, 22:02   #2
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Re: Membrane Life Expectancy

This is really a tough question to answer. Unfortunatly all membranes are not the same. Even ones made from the same batch. But on average with a well taken care of watermaker figure a 5-8 years is a good life expectancy. I've seen them last longer past 10 years but it's the rare exception not the rule. Twenty years is just unheard of. But then I've said before, I have a neighbor that has an original Chevy Vega with 235,000 miles on it. Some things defy logic. There are a lot of things that can affect a membranes life. Most of it is how they are taken care of and sometimes there are things due to manufacturing that an owner has no control over. But membrane materials and manufacturing has come a long way in just the past ten years. There is still a lot of confusion and disagreement on the best way to take care of membranes. But the ones that seem to last the best are run for at least two hours each run time and fresh water flushed after each use and flushed again at least once a week if they are not used or pickled. PUR80 uses a propriatary membrane as you know and are some of the most expensive for their output. But they can be found many places around the world. I'd probably keep the membrane you have now if you are getting the proper PPM levels. It's very rare that a membrane will have a complete failure all of a sudden. Usually a membrane failure will be gradual enough that if you're reading the PPMs regularly you'll have plenty of warning and time that a new membrane will be eventually needed. Of course crossing oceans you should never rely on any watermaker to get you across but rather use it to top off your tanks as you use water and the level drops off no more than 1/4 just in case of any failure. Also with only 40 gallons you should be carrying a few blue water jugs for crossing as well.
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Old 22-03-2012, 23:19   #3
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Re: Membrane Life Expectancy

And rain water collection devices. Simple clean tarp with a drain fitting to a hose to go into a tank. Make sure to screen it also. Rain water offshore is usually clean
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Old 23-03-2012, 02:07   #4
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Re: Membrane Life Expectancy

G'day, mate. Let see, my receipt from Applied Membranes is dated 09/26/02 so just coming up on 10 years. We regularly lay the unit up for extended stays away from the boat. When we do have it in service, we make usually make water on a daily basis. Having said that we have just went through a stretch of a week when mother nature have provided ample amounts of fresh water. We do NOT back flush with fresh water when we shut the unit down when using it. Hope that helps. Cheers.
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Old 24-03-2012, 08:44   #5
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Re: Membrane Life Expectancy

I talked to HRO systems. My membranes are about $400 US each. ALso, if you get an extra one, make a PVC tube holder for it and pickle it about 1 time a year, it will be almost indefinate lifespan on the shelf. For my way of thinking, $400 X 2ea for me, is not too much to spend every few years for fresh new membranes. I will take the ones I have that are being used and use them as spares. I knw they are OK, and wen $ allow, I will get a new back up set. They are not too big, and water is a big isssue. SO maybe keeep the used ones that are good also.
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