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Pat, the low pressure gauge failure is not uncommon. About one third of the Amels I get for resale have failed low pressure gauges and owners who have replaced them more than once...
JOEL F. POTTER
CRUISING YACHT SPECIALIST LLC
THE EXPERIENCED AMEL GUY
On Aug 25, 2018, at 3:40 PM, Patrick Mcaneny sailw32@...
Right or wrong,good or bad, I went ahead and ran it in our fresh/brackish Sassafras River. After three years idle all went well , no leaks but I never went above 140 Lt/hr. and no where near the green zone. My low pressure gauge has never worked , it could be because I installed the system and did something wrong. Am I correct in assuming the LP pump must be working ,otherwise I would not be able to produce water ? I ran it six months like that and always got up to 160/hr. Any hints why the gauge may not be working.
To: amelyachtowners <amelyachtowners@...
Sent: Sat, Aug 25, 2018 2:28 pm
Subject: [Amel Yacht Owners] Re: Watermaker and transmission fluid
PS: A little more reading on Filmtec was interesting in that their BW and FW are indeed manufactured to very different specs than the SW, being designed for constant use in those waters. Less pressure is used and thus energy savings are had. They've even got special membranes for maple syrup! Who 'da thunk? An extensive technology behind it all well beyond our SW marine membranes (which are happy with BW or FW).
Yes, the reply Alan got from Dessaltator sounds very much like the reply I got from Alden Barbour that you can only use sea water to cool your refrig. At least they were straightforward enough to say that's because of the remote possibility of the freon line breaking into your water tank and you might sue them, not for any engineering reason.
The U-Tube link you gave in your post is the one I noted earlier of Rich Boren of Cruise RO saying there's no problem running your watermaker in fresh water, just keep the pressure down. So, he says, go ahead and sail the brackish Chesapeake or fresh Great Lakes and clean with fresh. Combine that with the Filmtec letter saying no problem and it's pretty clear Dessalator is simply in PYA mode.
It would be interesting to see if Filmtec would supply an explanation of any technical difference in their membranes designated for salt/brackish/fresh water membranes? It sounds like marketing, not engineering, or, possibly, the BW and FW membranes are engineered such that they will pass salts but not bacteria so one could use the SW in BW or FW but not vice versa, but I'm just guessing on that.
Cheers, Craig SN68
, wrote :
I find that reply from Dessalator quite intriguing. I cannot speak to that statement exactly, because my watermaker was 'hybridized' some time ago and is not purely Dessalator any more but here is one possibility why they (Dessalator) would be so adamant about fresh water usage.
Even though the the membrane(s) are fine pushing low volumes of fresh water through them when rinsing or even when doing the "double-RO" function, it is not what they were designed for. The membranes from Filmetch come in specific version for salt water, brackish water and fresh water. The one I have installed is definitely bred for saltwater (Model SW30-2540). The SW actually stands for Sea Water. There are BW (Brackish Water, TW (freshwater or Tap Water) and a couple of others I think (a nano-filter and
a low energy usage membrane).
At any rate, the SW30-2540 membrane is indeed technically designed for Sea Water so I get where Dessalator is coming from. However, talking with two different water maker experts (Cruise RO and Dessalator Malta) and coupled with my own experience I will say that testing and backflushing with filtered fresh water, even running the high pressure pump to provide a testable water sample would not cause harm. As mentioned, don't let the flow go high, as fresh water will pass cleanly through the membrane at much lower pressure).
I would not, however, use the watermaker in fresh or brackish water for the long term without swapping to a purpose-designed membrane for it.
There you have an "official" 2 cents worth :)