Re: Water Maker question

asm283 <no_reply@...>

Thank You gary

This is very helpfull.


--- In, amelliahona <no_reply@...>

--- In, asm283 <no_reply@> wrote:
Hi Vito:
As far as I can determine there is only one manufacturer of RO
(Reverse Osmosis)
membranes in the world. That manufacturer is FilmTec. FilmTec was
a rather
small company that manufactured membranes by hand until Dow Corning
them a few years ago and developed robotic manufacturing
processes. This
development resulted in improved membranes that give higher
than the original hand laid up membranes. The other great benefit
was a drop
in price. The membranes are less than 50 percent of their original

The membranes on my Amel SM 2000 Hull # 335 (220 VAC 50 Hertz
150 l/hr water maker) are FilmTec SW30-2540 (that is SW = Sea
Water, and the
2540 = 2.5 inch by 40 inch membranes. I suspect that yours are the
same. I
purchased mine from a company Air, Water, Ice. Inc., Phone in USA
is 776-461-0256.
Walter is the owner and is very knowledgeable. The Film Tec web
site shows that
the SW30-2540 will produce 166 liters/hr for two membranes at
optimal temp.
The rate is higher than the original design for the Dessalator
system because of the
higher quality membranes (29 square feet surface area) that is due
to robotic
glue lines on the membranes.

As I searched the Dow Corning Film Tech technical literature I
wasn't able to find
any evidence that the salt rejection rate of the membrane is
affected by temperature.
The reading from the TDS meter may change due to temperature though
as you are
literally measuring electrical conductivity of the water and this
is affected by temp.
The salt rejection rate is dependent on pressure and if the
membrane isn't operated
at optimal pressure the TDS (total dissolved solids) will be

You didn't mention if the water you tested was the first out of the
system after start
up or if you waited at least 5 minutes before testing. See my
previous post related to
TDS Creep that occurs upon system shut down. It takes a few
minutes for the TDS
Creep to go away after system start up.

In answer to your questions:
1. Possibly. This could also be due to worn 0-rings on the end
caps and membrane
nipples (see photo section under watermaker). Product rate may
actually increase
as the membranes fail (that was the case with mine).

2. Cleaning is recommended and the procedure is described on the
Dow Corning
Filmtec web site under literature. This is more likely to cure a
falling production
rate than to cure a high TDS. (1000 TDS isn't really that bad.
City water is
commonly 800 - 900 ppm. My system with brand new membranes produces
water at 485 microSiemens/cm = 500 ppm TDS at 160 l/hr).

3. I had great service from the supplier I mentioned above. If
they are shipping
over seas request them to double package them. The shipping
they sent mine in was somewhat damaged just shipping across the
damage to the membranes but it would have been damaged if they had
much more handling.

4. See my response above. I also have a post on this site about
process of replacing the membranes. About a 4 hour job but requires
some means of grasping the tubes and end caps, (see the photo

Hope this helps. Feel free to contact me if you have further

Finally, install a independent continuous EC or TDS monitor as the
Dessalitor Salinity Sensor connects to pins on the control board
have no electrical traces to any control circuity. It is my opinion
that the sensor is a sham installation that was never functional.
Either that or there was gross manufacturing defects in the system.
Don't depend on the Dessalator system to alert you to unsafe water.

Regards, Gary Silver s/v Liahona

Hello from Fiji

Well of course problems will crop up in the most remote places. I
recently bought a water saltinity tester. The water coming from
watermaker is testing at 1200 PPM. The water from the tap is
at 1000 or under ppm and when I test the water from a
bottle it tests at around 600 to 700 ppm. My conclusion is that
temperature has a lot to do with test results. Anyway all these
results are above normal. Now my watermaker could have been
this quality of water all along I just had no way of testing.

My questions are.

1- Does the higher readings mean that the membranes are going
Product amount is normal.

2- Does cleaning the membranes with a solution help.

3- Can someone recomend a supplier for the membraned in the US or
south pacific.

4- Does anyone know what the model # of the membrane is. I have
150 LPH 220 model.

PS I tested the saltinity of red wine and it 1050 PPM. So maybe I
making too much out of this.

Any help or advise would be gladly appreciated.

Thank you

Vito Ciaravino

asm 283

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