Watermaker maintenance, am I missing something?

[Sailormantx]

There have been any number of posts claiming 5 years of life from R.O. membranes, but I can only get one to one and a half years out of mine. They are flushed with product water after every use and never sit unused more than a few days, unless I am laying up the boat when they would be pickled with preservative. Cleaning chemicals are run through them once a year or as needed. The TDs measurement on my current set has slowly climbed to the 600+ range over the course of a year and cleaning has made no difference. However the boat is currently in freshwater and the TDs promptly dropped to 3-5 as soon as I was out of the saltwater. I do avoid using it in very polluted harbors, but do spend a lot of time in rivers with muddy waters, so there are 2 prefilters in the system. It is a Sea Quencher unit with two 21" membranes that I purchased new in 2000.

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[belizesailor]

You're missing something. Even a poorly maintained membrane should last that long. I got about 8 years out of my original and am several years into the new one. No need to run cleaning chemicals annually if properly maintained.

Are you sure its the membrane? There are other factors that can cause PPM to rise.

I dont know your make of system, but have heard that some dont like freshwater use.

[Tellie]

Is there a charcoal filter inline with your fresh water flush and do you change it twice a year? Are you using anything in your fresh water tank/s to keep them clean, Clorox etc.

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[Kenomac]

Ours was fine even after being pickled by someone else at one time for over six years. We got ten years out of that one.

Have you tested or replaced your high pressure pumps? How's the output from the high pressure side of your system?

[Sailormantx]

There is a charcoal block filter inline on the flush, I put a new one in if I take on dockside water, otherwise it is exclusively r.o. water in the tanks, with no chlorine added. The oil is changed in the high pressure pump every 500 hours, nothing else has been done to it. I recently delivered a boat that had a Village Marine system that was identical to my Offshore Marine excepting that it had only one membrane, where mine has two. I did notice that the output flow was a steady stream, where mine show a noticeable pulsing in the flow.
Reasonably sure it is the membrane causing the rise in td's, the logbook shows a steady rise since it was installed.
I am searching out a parts kit for the HP pump, as the oil seal on the output shaft has begun to leak. Perhaps I should change out all the parts in the pump?
Output and td' are fine in freshwater, but in seawater it was down to about 5 gph, should be 8 gph under ideal conditions with new membranes, though typically it is around 7+/- depending on temperature and salinity.

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[Sailormantx]

Also, I am careful to keep the pressure between 800-850 in seawater, and adjust it so the flow does not exceed 8gph in freshwater, usually 125-200psi.

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[Kenomac]

According to the head technician over at Spectra, if the high pressure pump output has fallen off, it will appear as though the membrane performance has also fallen off by producing more ppm in your tests.

[Captain Bill]

Originally Posted by Sailormantx

There is a charcoal block filter inline on the flush, I put a new one in if I take on dockside water, otherwise it is exclusively r.o. water in the tanks, with no chlorine added. The oil is changed in the high pressure pump every 500 hours, nothing else has been done to it. I recently delivered a boat that had a Village Marine system that was identical to my Offshore Marine excepting that it had only one membrane, where mine has two. I did notice that the output flow was a steady stream, where mine show a noticeable pulsing in the flow.
Reasonably sure it is the membrane causing the rise in td's, the logbook shows a steady rise since it was installed.
I am searching out a parts kit for the HP pump, as the oil seal on the output shaft has begun to leak. Perhaps I should change out all the parts in the pump?
Output and td' are fine in freshwater, but in seawater it was down to about 5 gph, should be 8 gph under ideal conditions with new membranes, though typically it is around 7+/- depending on temperature and salinity.

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I'm wondering if your seals in the HP pump pistons are worn and you are leaking a bit of oil into your raw water stream. Your output shaft seal has enough wear on it to leak, perhaps the pistons do too. I used a Katadyn 160 for many years and used the same pressure vessel and membrane with a three piston pump and the TDS was twice as high with the single piston Katadyn pump as it was with the continuous flow of the three piston pump. I have often observed that if pressure is removed from the membrane for even a few seconds that I get a pulse of high TDS water after pressure is restored. With the Katadyn there is low/no pressure on the membrane 50% of the time because it is a single piston pump. I don't know what high pressure pump is used in your particular model as these pumps come in 1, 2, or 3 piston versions. If your pump is a three piston model and you are getting pulsation your pump is broken. At least one of your pistons is not producing pressure, either through wear or a non-functioning check valve. This might also account for your lower output in seawater, which requires much higher pressure than fresh water. I manually control the pressure in my current unit and I get some flow at 600 psi, but I need 800 psi to get full rated flow. If your pump is producing only 6-700 psi because of wear or a bad check valve on one piston it could easily account for your reduced sea water output while being perfectly adequate for fresh or brackish water. One other possibility is that the pressure regulating valve is bad and can no longer maintain the high pressures required for seawater.

I looked at the web page for the modern version of your unit and it says that it has an automatic pressure regulating valve that maintains proper pressure.
It also says it is good for fresh, brackish, and seawater. It's not clear to me what kind of valve is doing the regulating, but if it's a typical spring compression valve it will be set to a particular pressure, probably the 800 psi required for seawater RO. Many experts including those here on CF, recommend adjusting pressure based on rated flow rather than a constant pressure. For instance in fresh water I only need about 150 PSI to get 30 gph of product water which is the rated flow of my membrane. If I ran 800 psi in fresh water I would exceed the rated flow of my membrane by many times. These experts tell me that running a membrane at above their rated flow is bad for the life of the membrane. Since you state you are often running it in fresh or brackish water, if your unit is maintaining seawater pressure levels, that could account for your short membrane life.

[Captain Bill]

It looks like you addressed some of my concerns while I was writing my previous post. based on what you said and your description of the pulsed output I would think that your HP pump is still suspect. Pressure gauges have a lot of inertia and may not effectively display a low pressure pulse on one piston in multi-piston pump, though you might see a slight vibration in the needle rather than it being rock steady.

[Tellie]

"It is a Sea Quencher unit with two 21" membranes that I purchased new in 2000. "

2000?

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[Badsanta]

The watermaker school I went to stated that each time you used a membrane cleaner you shortened its life and that the preservitive did not protect it from freezing temperature. That the best way was to flush with ro water and pickle with potable antifreeze the pink stuff under no pressure. Then flush alot before using under pressure again. Your results may very.

[Monepit]

Originally Posted by Sailormantx

There is a charcoal block filter inline on the flush, I put a new one in if I take on dockside water, otherwise it is exclusively r.o. water in the tanks, with no chlorine added. The oil is changed in the high pressure pump every 500 hours, nothing else has been done to it. I recently delivered a boat that had a Village Marine system that was identical to my Offshore Marine excepting that it had only one membrane, where mine has two. I did notice that the output flow was a steady stream, where mine show a noticeable pulsing in the flow.
Reasonably sure it is the membrane causing the rise in td's, the logbook shows a steady rise since it was installed.
I am searching out a parts kit for the HP pump, as the oil seal on the output shaft has begun to leak. Perhaps I should change out all the parts in the pump?
Output and td' are fine in freshwater, but in seawater it was down to about 5 gph, should be 8 gph under ideal conditions with new membranes, though typically it is around 7+/- depending on temperature and salinity.

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I'm very new to water makers but you say output in fine in freshwater. All I've read is that you should never use them in fresh water.

[Sailormantx]

Yes, 2000 was the year I purchased the machine, took it off my last boat when I sold it in 2003. The hp pump is a single piston size, and it has no trouble at all pushing the pressure over 900 psi if I try to adjust it too quickly. Last time I changed the membranes, everything was normal, but the td readings steadily increased over the course of a year. Currently searching out a source for new o rings for the pressure vessels and a 708_1 routine service kit for the hp pump. I am finishing up a job in the USA and will be returning home to the boat with a duffle bag full of boat parts including another set of new membranes.

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[Tellie]

Originally Posted by Sailormantx

Yes, 2000 was the year I purchased the machine, took it off my last boat when I sold it in 2003. The hp pump is a single piston size, and it has no trouble at all pushing the pressure over 900 psi if I try to adjust it too quickly. Last time I changed the membranes, everything was normal, but the td readings steadily increased over the course of a year. Currently searching out a source for new o rings for the pressure vessels and a 708_1 routine service kit for the hp pump. I am finishing up a job in the USA and will be returning home to the boat with a duffle bag full of boat parts including another set of new membranes.

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I just wasn't sure if you were saying the membranes were from 2000. If you are getting a pulsating flow then it is very likely that your problem with early membrane failure is due to the high pressure pump. Membranes do not like getting pounded by water pulsation and it will lead to an early demise. As you noted on the boat you delivered, you should have a steady even flow from both the product line and the brine discharge. I would probably suggest a full rebuild kit for the pumps manifold, especially if you are taking it overseas. Membrane vessel O-rings should just be a standard replacement procedure any time the membranes are replaced.

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[Tellie]

Originally Posted by Badsanta

The watermaker school I went to stated that each time you used a membrane cleaner you shortened its life and that the preservitive did not protect it from freezing temperature. That the best way was to flush with ro water and pickle with potable antifreeze the pink stuff under no pressure. Then flush alot before using under pressure again. Your results may very.

!!


I'll be having a watermaker class in July in Fort Lauderdale if you want to join us.

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