Reverse Osmosis Filtering System


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Old 04-12-04, 05:12 PM
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The order of things (RO)

Here is what I have, 1- GRO700 light commercial RO system w/ 300psi 1hp motor. Will produce up to 700 gallons per day. 1- Carbon Filter, 1- AlamoBrand water softener with dual tanks, 1-Brine tank, 1- 200 gallon storage tank, 1- 40 gallon pressure tank and one recirculating pump. I believe the order of things is where Iím getting confused. Hereís what I think ? The supply water enters the carbon filter, then goes into the softener. From here it goes to the RO. Where Iím lost is on the connections for the pressure tank, storage tank and pump. I would think the pump would have to draw from the storage tank which would require a check valve somewhere but I just cannot picture this. Any help would be appreciated.
 
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Old 04-12-04, 07:27 PM
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The pressure tank can go anywhere in the vicinity of the pressure side of pump. The check valve will either be built-in to the head of pump, or use of a foot valve at the end of suction line.


I prefer check valves close to the pump, the average user doesn't normally have the capabilities to gain access to the suction line in the well/cistern. The difficulty factor goes way up.


Goodness gracious, what is the deal with the water in Texas? That bad? Kinda makes me feel guilty for having city water, turn it on and use it.
 
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Old 04-12-04, 07:45 PM
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Water in Texas ?

Water in Texas ? Nope, we use these RO systems to refine crude oil, we separate what water we can and ship that oily stuff up north there. On a more serious note, fresh water in West Texas is more valuable then our oil. Thanks for the information, it makes sense now.
 
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Old 04-13-04, 02:51 PM
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What is this water going to be used for? What's the analized need for the carbon filter?

Carbon should not be used on water of unknown microbiological content; in other words if there's bacteria in the water no carbon. And there's bacteria in all water that doesn't have a proper amount of Free Chlorine residual. Bacteria love the environment in a carbon filter so if the carbon filter allows bacteria past it to the RO membrane, the membrane will fail. Biofouling of the membrane is the primary cause of membrane failure. GAC or Centaur carbon can not prevent bacteria from exiting the filter.

So unless the carbon is needed to protect this RO, it should go after the atmospheric storage and that should be disenfected storage if this is meant to be potable water. Hence a disinfectant is removed by the carbon filter as the water is sent to the fixtures.

The pump should not be a recirculating pump, it should be a repressurization pump. It goes after the atmospheric (non-pressurized) storage tank. The pump would take water from the storage tank and send it to where ever the water is needed or going to be used. The pressure tank would be just after the pump and a pressure on the pressure tank or flow switch in the plumbing would control the pump. Depending on what type of pump this is, jet or submersible, the check valve will be in or on the outlet of the submersible pump or on the water line inlet in the tank gooing to the jet pump. You don't want a check valve on a jet pump at the pump, only on the inlet of the suction water line. That applies to either type of jet pump; shallow well suction only single line or, deep well two line with the jet in the j-body in the well wit ha foot valve on the bottom opf the j-body. They are commonally called a foot valve and should have an inlet screen on them.

RO water is very aggressive water. Aggressive due to high DO content. So you don't want to use metal plumbing, plastic only.

So... water source feed, softener, RO pressure pump, RO outlet, into storage tank, repressurize pump to pressure tank to maybe carbon filter and on to water fixtures. The RO pump solenoid etc. should be controlled by a float switch in the storage tank. The repressurizing pump should have a low water float switch or safety cut-off pressure switch to shut it off if there's insufficient water in the storage tank. And I may have missed something so double check.

The disinfectant that I would suggest would be a special inline pellet type chlorinator. Or if money where no object, an ozone bubbler in the storage tank. Then I wouldn't need the carbon filter and it's maintenance plus pressure loss.

Gary Slusser
 
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Old 04-13-04, 05:50 PM
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Carbon Filter

Gary, after reading your reply I started to wonder, what in the world am I doing trying to install this system. I donít know enough about RO systems in the first place but thinking Iím mechanically inclined I should be able to follow instructions. (You know, those things that come with items on how to assemble, that most men donít read) But your question on the carbon filter made me stop and think, did I need a carbon filter or did I just encounter a good salesman. This RO system is for domestic potable water (for drinking only) I had sent in a water sample to the company providing me the equipment with the information they requested on demand use, maximum gallons required etc. and received this setup. (Maybe them knowing money was no object incorporated the carbon filter.) So acting like I didnít know a whole lot about RO systems (which I donít, but no need to tell them that (sort of a pride thing for us men) and after reading your question about why a carbon filter, I contacted their representative and asked him why the carbon, and his answer was, and I quoteďCellulose acetate membranes require constant free chlorine to prevent bacterial growth and membrane damage. In contrast, polyamide and thin film membranes are damaged by free chlorine. Activated carbon is used to remove free chlorine when polyamide and thin film membranes are chosen.Ē end quote. So lets pretend I understood one word this guy just told me. (Which I didnít) He went on to explain the results of the water analysis for the supply water and assured me this was the proper method. Apparently our city uses enough chlorine in the water supply I should have no need to buy it at the store in order to keep my white shirts white. Gary I certainly appreciate the input and I will keep you posted on the amount and quality of water I get from this system. And P.S. The representative remarked ď Donít worry, these membranes will last a good three years past the warrantyĒ So I made him put it in writing before I cut the check. If for some reason this does not sound correct I hope you will post back so I could investigate the matter further. Again thanks for your time and for all the responses I have received.
 
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Old 04-14-04, 07:12 PM
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wow! Those guys should luv ya! Ok.. chlorinated city water and they sold you a POE (point of entry) RO for drinking water production. If you only have a house, that's a lot of drinking water. They probably wouldn't entertain the idea, but you should send it back IMO. It certainly is overkill even for the worst city water I've ever seen but... they're right about the chlorine and membranes so the carbon filter goes before the RO and it might as well go ahead of the softener to protect the resin from the chlorine. They are wrong about carbon keeping bacteria away from the membrane though; bacteria thrive in carbon. And with it ahead of the softener, bacteria in the RO is a much higher probablility. About equal to it being after the softener. You would have been better off with CTA and no prefilter carbon. that's just my opinion but whatever, keep the carbon replaced on a timely manner.

As to installing it, yeah read the instructions as soon as you run into a problem you can't solve otherwise. lol

Gary Slusser
 
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Old 04-15-04, 06:35 PM
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Gary, Thank You

Gary, thanks a million for the info. This system is for drinking water for a bit more then five hundred employees. If I could query you one more time, could you suggest something ahead of the carbon filter to handle bacteria? I donít mention this to my sales reps but the money is not the issue, I would just like to provide the best water at the most efficient price. I have read some on ultraviolet but here again Iím Mr. Rookie. Thanks again for your help. And what is this CTA you spoke of.
I apologize if I am taking up much of your time on this. I appreciate all the information and help I receive here. If any compensation is in order, you just let me know.
And, sincerely I thank you.
 
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Old 04-15-04, 09:07 PM
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Hi Richard. Ok now I see the need for that type RO. You do know you can't run that (RO) water through metal plumbing right? It will eat it up like right now. That adds the metal to the water and thins the wall of the tybing until it developes pinhole leaks.

CTA is their Cellulose acetate. It used to be called if it isn't still, cellouse tri-acetate. But it's been awhile since I read up on RO membranes.

IMO your atmospheric storage tank should have the disinfectant applied in it rather than after it. And then the carbon would remove it. Personally althoug hI don't like chlorine, I'd suggest a special inline chlorinator using FDA grade for potable water chlorine pellets. Especially with the use of this water in a commercail or business environment. I may follow the carbon filter with UV. I like UV and have sold many of them over the years but... that tank is going to need cleaning sometime and much more often if there's no disinfectant in the water. You can't keep an atmospheric storage tank water sterile or in other words safe from life forms that shouldn't be in what is assumed to be potable water. In your case I assume you'd have a real large liability in that regard.

I post as a way to help others so I won't send no bill! lol But if you want more info, this isn't the best way for specifics as to what and how to do it.

Gary Slusser
 
 

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