How Long Does a RO Membrane Last?

[nimblemotors]

I'm not having much luck finding the answer. Seaching CF didn't help.
I've found on the internet references from 2-3 years, and also 5-10 years.
The 2-3 years seems to be when operated 24x7 in an industrial plant.

So let me ask actual boat owners how long before they had to replace the membrane?

[Captain Bill]

Mine lasted 12 years, but only 5 of that was in regular use.

[SV THIRD DAY]

Dow Chemical makes what many consider to be the Gold Standard in RO Membranes and they rate their sea water membranes with a 7 year life span of 365/24/7 usage. But that doesn't necessarily mean you will get longer life out of a batch process water like those found on cruising boat for several reasons. The recovery rate on an industrial continually operated RO Membrane is 7%. On batch process water makers it can be as high as 25%. The truth is a cruising boat water maker won't wear the membrane out from use or some maximum treated gallonage, but most likely from poor maintenance and care.

We give a 3 year full replacement warranty on our SM30-2540 Dow Filmtec RO Membranes and have VERY FEW warranty claims. So that should tell you that we are darn confident they will last at least 3yrs.

So what's the real life life span? I say 4-7years depending on care and inlet water source. I know there are reports of a 15yr old membrane out there working great, but if I got 6-7 yrs out of a $187 40" RO Membrane, I would smile and replace it feeling that I got my money's worth.

[nimblemotors]

No other reports from real-world lifetimes? Or does nobody want to admit they mistreat theirs and they replace them once a year??

The reason I am asking is because I'm considering making a membrane with an integrated housing, which would be half the cost of a membrane and housing, but more expensive than a membrane to replace. This makes sense to me if they really last 3-10 years,
but would not make sense if in the real world boat use they are replaced every 1-2 years.

[SV THIRD DAY]

At $187 for a replacement SW30-2540 40" RO membrane I view them as long term consumables that need to be replaced every 5-7 yrs. We haven't seen cruisers needing to replace their membranes in the 1-2yr range. We sell about thirty 40" membranes per month to cruisers with all brands of water makers and when I'm taking orders from people I usually get feedback that their Membranes are lasing in the 5-7 yr range.

The hard thing with an intergrated Membrane/Housing would be the ongoing replacement cost. When cruisers are on a cruising budget rather than an outfitting budget the ongoing maintenance cost is an important issue. So if a cruisers can get a SW30-2540 membrane replacement for $187 and have that membrane be available world wide, trying to sell a more expensive and proprietary membrane/housing replacement I think would be a hard sell. Unless there is some performance or ease of operation improvement.

I'm not trying to discourage you...the world thrives on improvements and new ways to do things...but one of the big things people like about our brand of water makers is that we use no pproprietary parts. People know about the $399 or $599 RO Membrane and it really pisses them off when they could have bought one for $187. We get those calls all the time.

[Travelnik]

Rich,

Do you have a RO membrane that works with the Katadyn 35/40 watermakers?

[SV THIRD DAY]

Originally Posted by Travelnik

Do you have a RO membrane that works with the Katadyn 35/40 watermakers?

Unfortunately, Katadyn uses their own proprietary RO Membranes, so there isn't anything "off the shelf" that will work and you have to buy replacements from them.

[Travelnik]

That's what I thought, but it never hurts to ask.

Thanks.

[nimblemotors]

Rich, being able to replace just the membrane for $187 is great, but then you also have
to buy the $425 housing, Water Maker Parts

If the integrated membrane was $250, you could buy 2 of them and get 10-20 years and still come out less expensive. If you cruise for 3-5 years, one may never need to replace it. I do understand that companies tend to price their proprietary parts with huge markup. What I'm planning, one could replace the integrated unit with standard parts if desired in the future, unlike some designs where that is not possible.

[Scott Berg]

I've seen 12yr old membranes that were still producing at 85% of max rating... They last a kong time

[belizesailor]

Got about 7 years out of my DOW membrane in my Spectra Catalina 300. I think about 5 is more common, but it depends heavily on how well maintained. You could easily kill one more quickly due to poor maint/use practices.

[WombatWhiskers]

[QUOTE=SV THIRD DAY;1509324]We give a 3 year full replacement warranty on our SM30-2540 Dow Filmtec RO Membranes /QUOTE]

This past week I happened to mention to Spectra HQ I bought this exact membrane 2 years ago for $187 from another US RO supplier. The comeback was in effect "Dow Filmtec rates each membranes by quality - they ship the very best units to us, and the 'crap' to the low-cost suppliers. That's why ours cost so much more."

What's the real story? As far as I can tell this membrane works just fine.

Off-topic question from NZ: Is it safe to pickle with SC-3 for a couple of weeks? Because pressures have crept up from 85-ish to 105-ish I suspect the membrane needs an acid clean anyway. I'm in a rush to ship tomorrow AM our Clark Pump for a rebuild - and don't want to wait 2 days to restock on SC-1.

[SV THIRD DAY]

Originally Posted by WombatWhiskers

This past week I happened to mention to Spectra HQ I bought this exact membrane 2 years ago for $187 from another US RO supplier. The comeback was in effect "Dow Filmtec rates each membranes by quality - they ship the very best units to us, and the 'crap' to the low-cost suppliers. That's why ours cost so much more."

What's the real story? As far as I can tell this membrane works just fine.

Off-topic question from NZ: Is it safe to pickle with SC-3 for a couple of weeks? Because pressures have crept up from 85-ish to 105-ish I suspect the membrane needs an acid clean anyway. I'm in a rush to ship tomorrow AM our Clark Pump for a rebuild - and don't want to wait 2 days to restock on SC-1.

That's the funniest thing I've heard in weeks!

Look...what do you expect them to say when selling the Dow Filmtec SW30-2540 Membrane for $399 and word gets out you can buy the same membrane for $187? Do they tell you that they are just adding an extra $212 in for profit or come up with a cover story?

This is Dow Chemical we are talking about here, not some mom and pop company that plays favorites under the table for heaven’s sake. Dow doesn't make a grade A and B Filmtec membrane. Dow doesn’t send the pick of the litter to one company, while sending the runts to others. They make one SW30-2540 industry gold standard Membrane and most of the water maker companies buy them at the same quantity pricing. What they sell them for and what they admit to be an off the shelf part...well there is the difference.

Here is the Tech Data Sheet for the Dow Filmtec SW30-2540 Membrane

If I sound irritated...well I am.
It's one thing in my view to charge as much as the market will bear for your product, heck that's the American way. It's another thing entirely to LIE to customers and attempt to frighten them out of saving some of their cruising dollars. I'm disappointed that someone at a reputable water make company would go down this road because the internet is the great equalizer in giving clients/cruisers the necessary information to sniff out and call out vendors that would give bogus answers.


I wouldn't want to use the SC-3 cleaning solution as a long term pickling reagent personally, but for only a 2 week period, I would just do a fresh water flush at the 7 day mark and skip the pickling all together. Even with your clark pump removed for servicing, you can use any pump you have aboard to push some chlorine free fresh water through the membrane to keep the bugs from growing.

[WombatWhiskers]

Originally Posted by SV THIRD DAY

If I sound irritated...well I am.

Rich - thanks heaps for your instant reply. I understand your irritation. I inquired because it didn't make sense for exactly the reasons you outlined.

Plus - it's hard to believe that Dow's process control could be so poor that there would be measurable variance in unit performance.

Bottom line - passing out such information raises ??? about the reliability of the source.

Originally Posted by SV THIRD DAY

I wouldn't want to use the SC-3 cleaning solution as a long term pickling reagent personally, but for only a 2 week period, I would just do a fresh water flush at the 7 day mark and skip the pickling all together.

I was thinking the same - then realized maybe I should be doing an acid clean anyway. If true, then the pickling for 2 weeks is a "free lunch".

From my Spectra log:
Membrane is at 625 hours since new. Our 52-ft catamaran system is unusual because Spectra is on wingdeck about 1 meter above DWL. The seawater supply is pressurized by our seachest pump (feeding the genset) at typical flow rates of 34 LPM.

I'm attaching samples from our log of performance measured only when VDC >= 28V. Note how the panel pressure has ramped up while production fell off.

If you look at 11/3/2012 note that pressure and production both down because we are powering - no seachest pump.

What are your thoughts on performance, whether membrane would benefit from an acid SC-3 clean?