Ro Membran Wet or Dry ?

Hi All,

I would need to know the difference between :
TFC membranes wet or dry ???

Ronald

[Discusgeo]

Ronald I am not going to make a stupid comment on what wet or dry is because I don't quite understand the question you are asking. But I can give you some info on what a TFC membrane is compared to a CTA one.

It is very important to determine the style of reverse osmosis membrane your system uses. It will either be a CTA membrane or a TFC style membrane. CTA membranes are made to allow contact with chlorine in the water. TFC membranes are chlorine "intolerant" and cannot come into contact with chlorine. The chlorine will destroy a TFC membrane. CTA membranes typically use a sediment prefilter and pass the chlorinated water into the tank. The carbon post filter then removes the chlorine. A TFC membrane uses a carbon pre filter before the membrane to remove the chlorine and then another carbon filter after the membrane to "polish" the water just before dispensing. TFC membranes have a higher rejection rate of many chemicals than CTA membranes and the extra carbon filter additionally removes more contaminants than the single carbon filter used in CTA systems. TFC membranes will typically last 3 to 5 years. CTA membranes typically last 18 to 24 months. The only way to know if your membrane is working correctly is to measure and compare the TDS (total dissolved solids) in the incoming feed water and the product drinking water. To do this you will need a TDS Tester.

Hi George

Thanks for the info so far.
My question relates to this : "Dow Filmtec TFC membranes are available wet or dry"
What does that mean ?
I could purchase a membrane called "TFC DRY MEMBRANE"
or I could purchase one called " TFC WET MEMBRANE"
What is the difference ?

Hope that clears the question up a bit.

[RandalB]

Ronald,
They are referring to Wet pack or Dry Pack membranes.

Wet pack membranes are shipped in a preservative solution (Sodium Metabisulfite) and should be refrigerated when stored. They have a limited shelf life and should be used immediately.

Dry Pack Membranes are as described, shipped dry and do not have to be refrigerated. They have an unlimited shelf life as long as kept dry and in a cool place out of direct sunlight.

The only real difference between the two is Wet pack are slightly more efficient in terms of solid rejection which does not make up for the difficulty in storage and use. You also have to rinse the solution from the membrane prior to use.

I would stick to the Dry Packs, cheaper and easier to use.

HTH,
RandalB

PS you might want to compare my prices on Filmtec membranes before you buy elsewhere..... ;D

[RandalB]

BTW George,

CTA membranes are also a lot cheaper and less efficient than TFC (5% less rejected solids from some manufacturers) and need more waste water to prevent fouling....



RandalB

Thanks for the info RandalB

Ronald