--- In email@example.com, 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 bought
them a few years ago and developed robotic manufacturing processes. This
development resulted in improved membranes that give higher production
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 cost.
The membranes on my Amel SM 2000 Hull # 335 (220 VAC 50 Hertz Dessalator,
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 higher.
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 container
they sent mine in was somewhat damaged just shipping across the USA. No
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 the
process of replacing the membranes. About a 4 hour job but requires
some means of grasping the tubes and end caps, (see the photo section).
Hope this helps. Feel free to contact me if you have further questions.
Finally, install a independent continuous EC or TDS monitor as the
Dessalitor Salinity Sensor connects to pins on the control board that
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