Re: Dessalator Watermakers & Filmtec Membranes

Thomas Peacock

This is not an area of expertise for me. However, I would like to either make a couple of points or ask of couple of questions, depending on my depth of knowledge.

The Dessalator manual mentions not to run in water less salty than normal ocean water. However, a member of this forum, name escapes me, stated that you could run in brackish water so long as you did not exceed the water production rate, which for me is 60 liters per hour. My theory on why was that either high pressures, or high water production rate was potentially harmful to the membranes. Is this correct?


Tom Peacock
SM 240 Aletes
Chesapeake Bay

On Sep 9, 2020, at 3:23 PM, CW Bill Rouse <brouse@...> wrote:


Not according to Dessalator who states that the green bar on their high-pressure gauge is set for between 60 - 65 BAR. And according to Filmtec the Maximum operating pressure is 69 BAR

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar

On Wed, Sep 9, 2020 at 2:17 PM Matt Salatino via <> wrote:
Won’t running over 56-58 bar affect the membrane life?
Off hand do you know the pressure range specs for the membrane?
I run ours at the low end of the green, thinking I’m being safe.

On Sep 9, 2020, at 8:49 PM, CW Bill Rouse <brouse@...> wrote:

I learned something today with from a great 54 owner, from Dessalator, and from reading the recent specifications sheet for Filmtec SW30 membranes.
·        The actual pressure for the Green Zone on a Dessalator high-pressure gauge is between 60 and 65 BAR
·        In normal seawater temperature and salinity and at 55 BAR the SW30 series of membranes will produce:
o   SW30 2521 = 47 liters/hour or 3*47 = 141 liters/hour
o   SW30 2540 = 109 liters/hour or 2*109 = 218 liters/hour
·        Obviously the production rate with pressure set inside the Green Bar (60-65 BAR), will be greater than the above
·        Dialing back the pressure to change the product water production to the original specs of the watermaker may cause the water maker to shut down.
My statement of reducing the pressure to set the produced water in the sight-glass at the original output for the D50/60, D100, and D160 is no longer valid for normal water temperature and salinity. And the D160 with new membranes will produce over 200 liters/hour.


WARNING: Filmtec has increased the efficiency of these membranes and depending on the age of your membrane(s) you may not see the increased production.

I attach the Filmtec Spec Sheet that I refer to:

I hope this helps and clears up things.

CW Bill Rouse Amel Owners Yacht School
Address: 720 Winnie, Galveston Island, Texas 77550 
View My Training Calendar

Tom Peacock
SM 240 Aletes
Chesapeake Bay

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