RO membranes

[reefermadness]

Originally Posted by StirCrazy

um, DOW doesn't make a 150, they also don't make membrains that the part number starts with TF. the DOW membrains that most of us use are
TW30-1812-GPD (24,36,50,75,and 100)

so you have managed to show a info sheet for a non dow product.

Steve

Apparently I did. I didnt realize that the 100gpd and 150gpd membranes that BRS sells are not dow filmtec. I got that spec sheet from their website.

How ever my understanding still is that all membranes must be used at the spec pressure to achieve the best rejection rate. You can up the pressure but you will see a decrease in the rejection rating.

You are right that all dow membranes are spec at 50psi. The 100gpd has a poorer rejection rating though, and they don't make a 150gpd.

[StirCrazy]

Originally Posted by reefermadness

Apparently I did. I didnt realize that the 100gpd and 150gpd membranes that BRS sells are not dow filmtec. I got that spec sheet from their website.

How ever my understanding still is that all membranes must be used at the spec pressure to achieve the best rejection rate. You can up the pressure but you will see a decrease in the rejection rating.

You are right that all dow membranes are spec at 50psi. The 100gpd has a poorer rejection rating though, and they don't make a 150gpd.

there may be a slight decrease in rejection rating, but it is not one that would be measurable and definatly not enough to be worried about.

we routeenly installed systems which were intended to make drinking water from untreated water and we would set them up at 100PSI. send in water samples and they would come back just as good as the plaves that have lower pressure. We also checked with DOW engineers befor setting them up this way. what we were led to believe is even at the max operating PSI of 150, the DOW filmtec would still have a better rejection rate than other brands. now this was about 8 years ago so who knows the quality of the copy brands now.

Now from running my own RO, at 50 PSI I get 0 PPM out, at 125 PSI, I get 0 ppm out. now that was with between 20 to 60 PPM in (depends on time of season)

Steve

[Doug]

Update. Removed the bypass. Installed the restrictor. It has increased the ro output, at least as much as a 50gpd can and has decreased the waste water some but, IMO, still makes to much waste water to ro water ratio compared with my 100gpd, which are the only two I have experience with.

[StirCrazy]

Originally Posted by Doug

Update. Removed the bypass. Installed the restrictor. It has increased the ro output, at least as much as a 50gpd can and has decreased the waste water some but, IMO, still makes to much waste water to ro water ratio compared with my 100gpd, which are the only two I have experience with.

remember if you don't have enough waist water it will cause your membrain to plug faster. ideal is 4 to 1, you can get away with 3 to 1

Steve

[Doug]

Originally Posted by StirCrazy

remember if you don't have enough waist water it will cause your membrain to plug faster. ideal is 4 to 1, you can get away with 3 to 1

Steve

Doing at least 4 to 1 Steve. If not more. I,m going to do a measure perhaps.