RO/DI help

[Ben1]

Here is the problem. I just got a new RO/DI unit. When I check the water from the tap it is 355. After the RO it is 120's, and after the DI it is still 1. I emailed the company and was told that it was because of my low PSI. I am only able to get a PSI reading of 36. What do you think is it b/c of the low PSI? Do I need a booster pump to fix this? How does a booster pump work with a autoshut off/float valve set up?

Thanks for any help you can give@!

Ben

 

[Anonymous]

Hmm. I wonder if the RO membrane is properly seated. Unscrew the cap, pull the membrane out and reseat it. There are two little o-rings on the bottom of the membrane. Make sure you feel them both snap in.

Louey

 

[Ben1]

Thanks, made me think but.....

I just triple checked it and it is fully seated. Nothing is ever a cheap fix in this hobby! Any other thoughts?

 

[Anonymous]

You need 7E's advise. He is very knowledgeable about the workings of RO units.

You could also email whoever you bought it from. They should be highly knowledgeable too.

Sorry I can't help any more than that.

Louey

 

[Anonymous]

>...What do you think is it b/c of the low PSI?

Not necessarily. First of all, make sure your PPM meter is calibrated, for example. What is your rejection ratio? If the ration is 3:1 (~355:120), then getting 120 out of the RO membrane is not unreasonable.

>...Do I need a booster pump to fix this?

Only if your PSI is too low. At 36 psi, it does sounds a bit low (I assume it is the static pressure, not when the RO is on), but only get a booster pump when you are forced to (may take you years to get the purchase price of the pump back from saving the extra water/membrane/DI)

>...How does a booster pump work with a autoshut off/float valve set up?

They are independent, and does not interfere with the valve.

 

[Ben1]

Thanks for the help Louey and 7E!

I tested the TDS and found it was 60 right after I set the unit up. I tested the next morning and got 120 off the membrane. Last night I tested off the membrane again and got a TDS or 68 from the RO only. I am using a 1:3 ratio as the guy I bought it from said to try that before the booster pump vs a 1:4 ratio to help increase thre PSI a bit.

So maybe a TDS from 355 to 68 from the RO isnt so bad?

Also my adjustable flow restrictor makes a constant noise like water is rushing through it while my old regular flow restrictor was silent, is the noise normal with this type of restrictor?

 

[Anonymous]

The output purity of the RO is dictated by the rejection ratio, among other factors, such as pressure, temperature, etc.. There is nothing free in the world, so to speak. If you adjust the rejection ratio higher, then the RO will be more pure, at the cost of more water is used.

Ajustable valve has a needle that can be moved, and as water move over it at relatively high speed, it will vibrates more easily than a rigid, fixed restrictor. This is why it can be more noisy.

 

[Anonymous]

I have to disagree with the purity being a function of the ratio. My purity with RO only goes from 180ppm to 8, and there no way in hell there's a 22.5:1 ratio of rejection. Typically membranes rated at 75gpd or less have "purity" ratings of 95-98%,

One thing mentioned was that you JUST got the system, and that you read 60ppm last night, one thing I remembered when I swapped out membranes there was a period of time when the TDS reading was higher, as if the membrane needed to "break in".

 

[newfish]

I have a kent 60gpd HI-Res RO/DI DLX and a pressure pump to get me at 70psi with a autoshut off at 40psi but the pump will not shut off and my RO unit will turn on and off just for no reason I did replace the autoshut off of the pump and it still's does the same thing. :?:

 

[Anonymous]

Did you check the output of the RO to see what pressure it gets? If there is a leak somewhere on the output line, the pressure will not be high enough to get the ASO valve to activate, and when it does not close, the booster pump will keep working until the line is 70 psi, which it never get there if the there is a leak anywhere.

 

[newfish]

thanks i will check it out

 

[Unresistible Blue]

Here is the problem. I just got a new RO/DI unit. When I check the water from the tap it is 355. After the RO it is 120's, and after the DI it is still 1. I emailed the company and was told that it was because of my low PSI. I am only able to get a PSI reading of 36. What do you think is it b/c of the low PSI? Do I need a booster pump to fix this? How does a booster pump work with a autoshut off/float valve set up?

Ben

Ben - not sure if you ever really got an answer to your questions.

A water pressure of only 36 psi will adversely affect your system performance without a doubt. For instance, if you have a 50 gpd Fimtec membrane, at 36 psi the best you could hope for is approximately 35 gpd. Its likely you have water colder than the factory spec of 77 degrees, so your output in terms of gpd would be less than 35. If you have a different brand of membrane, your situation will be worse as most other brands are spec'ed at pressures of 60 psi+.

You are getting only a 67% rejection ratio from your system now. You will burn through your DI resin very quickly at that rate.

Are you using a clean glass container to sample your system's output when you measure the tds?