View Full Version : flush valve

01/14/2017, 06:28 AM
I am using a Typhoon (I believe it's 75 gpd) with an additional 75 gpd membrane add on kit.

What is the correct flow restrictor/ flush valve for this unit?

I also have a booster pump: I have a psi meter right before the T that leads to both membranes (post prefilter and carbon block)... What pressure should this read for optimum product production?

01/27/2017, 10:20 AM
We use a 800 cc flow restrictor for 2 75 gpd membranes plumbed for PRODUCTION. In reality, everyone will experience different waste to pure ratios. The membrane specs desire a 15 % recovery rate.

What matters is this. You want to have the highest recovery rate possible without causing precipitation of supersaturated salt inside your membrane.

In our experience most people get about 3:1 waste to pure ratio using a 800 cc flow restrictor with 2 x 75 gpd membranes plumbed for production.

If you have questions, we are here for you.

01/27/2017, 10:32 AM
So would I still use the recommended 60psi or would I double it due to
2 membranes?

Yes, my membranes are plumbed for production.

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01/27/2017, 11:08 AM
60 psi works fantastic. Just as important - if not more important is your flow going into your system. We want 2 gallons per minute. Are you experiencing issues? I would love to discuss if so.


01/27/2017, 02:35 PM
I've got an 1100 on my current flush/flow restrictor and running about 80 psi. I yield about a gallon every 9 minutes. My system has been running for almost three years... one membrane is 3 years old and the other is 2... I have a tds meter on the output of each membrane and DI which consistently read 0 after flushing. Flushing takes about 2 minutes with the tds dropping to 0 from about 25-28. I flush every time I start the system.

My goal is to get as much product water as possible without damaging the membranes. I have very clean water from my tap at only 25 tds.

Any problems with what I'm doing? Any suggestions on maximizing production?

01/27/2017, 06:40 PM
If you are able to determine your recovery rate (how many gallons of drain water for ONE gallon of RO water), then we can look into making an improvement on your recovery rate to reduce drain water and increase production.

Max recommended psi is 75 at your house, that being said you can get a pressure reducing valve (prv) for $35 https://airwaterice.com/watts-pressure-regulator.html

Since you have the pressure, you could run 2 x axeon 150 gpd membranes (rated at 65 psi) or 2 x 100 gpd membranes (rated at 50 psi)

Pressure in excess of rating increase as production & rejection rate to a certain point.

01/27/2017, 07:45 PM
I am using a booster pump, without the pump my pressure is about 35 psi to the membranes.

I'll check my product to waste ratio tomorrow and report back. Thanks for all your help.

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01/28/2017, 07:36 AM
A booster pump is a game changer! Let me know if I can assist.

01/28/2017, 02:39 PM
Ok, so here are a few numbers for you..

I am currently using a flush valve/restrictor that has 1100 on it...

At 70psi I am getting 7gph of product to 19gph of waste. I have the source water plumbed to a cold water line... it's cold water here in Maine.

I know that is pretty good; however, I'd like to tweak that if I may to get better production.

I seem to be getting a very slow drip from the red valve handle on the flow restrictor and it hisses a little, it happens even when the pressure is dropped to 60. It doesn't seem to cause any harm so I've just lived with it.