RO systems.

[raybark]

From a practical perspective, I believe you would want to add a second booster pump if you add a second membrane.

Something you'll want to look into about booster pumps: most are installed on the inlet of the membrane housing, and are accompanied by a 40 psi pressure switch that shuts them off when the tank is full. The trouble with that is that the automatic shutoff valves on RO systems are designed to shut off flow to the system when the outlet pressure reaches 2/3 of the inlet pressure. If the inlet pressure is under 60 psi, then the shutoff valve kills the water supply before the pump pressure switch shuts that off. It seems plausible that if the booster pump was before the entire RO system, you'd be fine, but you had better make sure it can handle the flow rate of the permeate and brine streams, combined.

If you're going to collect the RO in an open-air tank, you don't need to fill the small bladder tank at all, and using another booster pump to do so is just impractical. For one, the typical bladder tank is too small for watering purposes - 3.2 gallons with about a 3 gallon usable capacity. I recently put together a system for a woman using a 20-gallon bladder tank (14 gallons of usable capacity), which roughly doubled the cost of the system, but she had a small collection and did not have space for an open-air tank and pump. My own setup includes a shallow-well pump fed by the RO tank. It has it's own bladder tank, and offers far more pressure and flow rate than a booster pump ever could, allowing me to water quickly and pressurize overhead misting.

I really think you should apply some creativity to the brine issue. All of the instrumentation, custom design and fabrication of membrane housings, and the like are costly, and the use of citric acid, besides being a pollutant, may not be as effective as you would like. To be honest, it seems to me that if the maintenance cost is truly less of a concern than the generation of brine, it would be a lot simpler to just gang several membrane housings with their brine outlets plugged.

[DavidCampen]

Originally Posted by raybark

From a practical perspective, I believe you would want to add a second booster pump if you add a second membrane.

Yes, a full 200 gpd system would require a second Aquatec 8852, with a single pump and a single Filmtec "100 gpd" membrane I should be able to get about 125 gpd depending on my product to waste ratio.

Originally Posted by raybark

Something you'll want to look into about booster pumps: most are installed on the inlet of the membrane housing, and are accompanied by a 40 psi pressure switch that shuts them off when the tank is full. The trouble with that is that the automatic shutoff valves on RO systems are designed to shut off flow to the system when the outlet pressure reaches 2/3 of the inlet pressure. If the inlet pressure is under 60 psi, then the shutoff valve kills the water supply before the pump pressure switch shuts that off. It seems plausible that if the booster pump was before the entire RO system, you'd be fine, but you had better make sure it can handle the flow rate of the permeate and brine streams, combined.

The Aquatec 8800 series pumps do not have a pressure shut off switch just a pressure bypass. If I was filling a pneumatic tank I would install an pressure switch external to the pump to shutoff the pump and feed water. An ASO will not be used since I will use a solenoid valve to shutoff the feed water. Since I will be dumping to an open tank I will use tank level controllers for these functions instead of a pressure switch.

Originally Posted by raybark

If you're going to collect the RO in an open-air tank, you don't need to fill the small bladder tank at all, and using another booster pump to do so is just impractical.

Actually, the pneumatic tank is not only practical but almost necessary. That is why the engineers that designed the well pump that you use as a delivery pump incorporated a pneumatic tank directly into its design as you mention below.

Originally Posted by raybark

... My own setup includes a shallow-well pump fed by the RO tank. It has it's own bladder tank, and offers far more pressure and flow rate than a booster pump ever could, allowing me to water quickly and pressurize overhead misting.

Originally Posted by raybark

I really think you should apply some creativity to the brine issue. All of the instrumentation, custom design and fabrication of membrane housings, and the like are costly,

Yes the instrumentation will be costly but will provide me with entertainment. The custom design I am doing myself and since I enjoy this sort of work I consider that to be zero cost. The membrane housing(s) will be standard.

Originally Posted by raybark

and the use of citric acid, besides being a pollutant, may not be as effective as you would like.

I wouldn't consider the citric acid to be a significant pollutant. It is non toxic and will be dumped into a sanitary sewer where it will be converted to carbon dioxide at the sewage treatment plant.

[raybark]

Originally Posted by DavidCampen

The Aquatec 8800 series pumps do not have a pressure shut off switch just a pressure bypass. If I was filling a pneumatic tank I would install an pressure switch external to the pump to shutoff the pump and feed water. An ASO will not be used since I will use a solenoid valve to shutoff the feed water. Since I will be dumping to an open tank I will use tank level controllers for these functions instead of a pressure switch.

David, I have installed them with Aquatec pressure switches. They are available in 40, 60, or 80 psi.

Solenoid is a good idea. That's how I did a 4 unit assembly not long ago.

Seems to me that a simple float valve would be sufficient.

Originally Posted by DavidCampen

Actually, the pneumatic tank is not only practical but almost necessary. That is why the engineers that designed the well pump that you use as a delivery pump incorporated a pneumatic tank directly into its design as you mention below.

I agree totally. I thought you were referring to the ones usually supplied with systems. The one on my jet pump is much larger and handles much higher pressure.

Originally Posted by DavidCampen

I wouldn't consider the citric acid to be a significant pollutant. It is non toxic and will be dumped into a sanitary sewer where it will be converted to carbon dioxide at the sewage treatment plant.

Whether you consider it so or not is irrelevant. The authorities might think differently. Of course, in small volumes you might get away with it.

Have fun with the design and assembly. When you start looking at purchasing, let me know and I might be able to get you some good prices on components.

[ttimpain]

RO is One kind of Machine which is used to pure a water.People have to attach in that house rather than drinking a normal water.The Normal water is danger to our health.The are various type of RO system available in market.