RO membrane output

[mark]

Something that comes up every once and a while is the effect of temperature and pressure to the output of the ro membrane.

Read that the GPD rating is based with the supply water at 77°C and 65 (or 60) psi and I've been reguratating a 1.6% drop in output per °F (from Aquasafe).

What started to wonder was how linear the drop with temperature was and found a couple of tables in this link: http://www.freedrinkingwater.com/infocenter.htm

As we all know the Internet is nothing but fact, but seems the last table is close for my unit (it doesn't get anywhere near the 100gpd rating).

[mark]

And there's even a calculator, just put in your membrane rating, PSI and temperature:

http://buckeyefieldsupply.com/calc.php

[StirCrazy]

the only problem with that is they are promoting there own membrain.

Dow is the industry standard and they are rated at 60psi/100psi the problem comes in when peole sell dow membrains and only tell you the higher flow and no pressure. say like a listing for a 100GPD membrain. so you buy it thinking this is the 60psi rating and when you run it the most you ever get is about 60gpd. the ones I use are the dow 100/160 and they do put out 160 gpd at 100 psi and about 75 degrees.

Steve

[mark]

Both links refer to the Filmtec membrane which points to Dow.

Eitherway, charts and link was more to point out the roll off in output if the source supply is less than the spec'd pressure and temperature.

[StirCrazy]

yup I find in the winter I get hit hard, water here is real cold as I am a short distance from the resavoir, thats why I have a 320GPD set up I probably only get about 150 during the winter.

Steve