Reverse Osmosis Information

**EDDperson91** · 03-24-2010, 08:56 AM

Hey everyone

We're looking for info regarding reverse osmosis, specifically the pressure required for it to purify saltwater. We need it for a project in which we've hit a roadblock in research.

Refer to this thread for info on the project:
http://www.wilderness-survival.net/f...ad.php?t=11026

Thanks in advanced

**Rick** · 03-24-2010, 08:59 AM

It depends are what you are purifying. 30-250 psi for fresh and brackish water and 600-1000 psi for saltwater.

http://en.wikipedia.org/wiki/Reverse_osmosis

**Ken** · 03-24-2010, 09:01 AM

"Q. How much pressure is required to purify water?

A. The pressure required is dependent on the concentration of the salt solution on the reject (concentrate) side of the membrane. Running as system at 1100 PPM on the concentrate side requires over 200 PSI. Sea water systems at 33,000+ PPM run at 800+ PSI. Under sink systems at home run at 50-70 PSI."
http://www.remco.com/ro_quest.htm

"The membranes used for reverse osmosis have a dense barrier layer in the polymer matrix where most separation occurs. In most cases the membrane is designed to allow only water to pass through this dense layer while preventing the passage of solutes (such as salt ions). This process requires that a high pressure be exerted on the high concentration side of the membrane, usually 2–17 bar (30–250 psi) for fresh and brackish water, and 40–70 bar (600–1000 psi) for seawater, which has around 24 bar (350 psi) natural osmotic pressure that must be overcome. This process is best known for its use in desalination (removing the salt from sea water to get fresh water), but since the early 1970s it has also been used to purify fresh water for medical, industrial, and domestic applications."
http://en.wikipedia.org/wiki/Reverse_osmosis

**Rick** · 03-24-2010, 09:03 AM

That is so lawyer like. Say exactly the same thing just use more words. Hmmmpf.

**Ken** · 03-24-2010, 09:16 AM

Originally Posted by Rick

That is so lawyer like. Say exactly the same thing just use more words. Hmmmpf.

How about this answer?

The required psi will be high enough to make your arm fall off.

**finallyME** · 03-24-2010, 10:05 AM

Man, you guys are fast. Wiki to the rescue. So much for a roadblock in research.

1000 psi ain't too bad. You will just have to make it out of some strong material. I recommend 316 SS. 304 might work as well.

**Ken** · 03-24-2010, 12:53 PM

FM, a thought here: What about incorporating a hydraulic cylinder into the design?

**finallyME** · 03-24-2010, 01:13 PM

Originally Posted by Ken

FM, a thought here: What about incorporating a hydraulic cylinder into the design?

You would probably have to. You can do it with gears, but they would have to be really heavy duty to keep from breaking teeth. At that point, hydraulic fluid is probably lighter. Basically take a bottle jack and stick it in a frame. A really long handle would also work, but it would have to be strong enough to take the moment.

I still think a distiller would be lighter and smaller.

**Ken** · 03-24-2010, 01:14 PM

Compressed air?

Say, like a CO2 cylinder?

**finallyME** · 03-24-2010, 01:44 PM

Originally Posted by Ken

Compressed air?

Say, like a CO2 cylinder?

It will work. But you will have to find one that can be pressurized that high. CO2 would be better than air. But, either would need to be recharged for continuous use.

**Ken** · 03-24-2010, 01:50 PM

Would it "self re-charge" to a sufficient pressure if you loaded a cylinder with dry ice?

**Pal334** · 03-24-2010, 03:21 PM

Originally Posted by finallyME

Man, you guys are fast. Wiki to the rescue. So much for a roadblock in research.

1000 psi ain't too bad. You will just have to make it out of some strong material. I recommend 316 SS. 304 might work as well.

But look what they did to Wikipedia :

Wikipedia down after server meltdown

http://scitech.blogs.cnn.com/2010/03...ltdown/?hpt=T2