Help with flow restrictor RO/DI

[atvdave]

In the past I have just been using a adjustable valve as my flow restrictor for my RO/DI unit.

I purchased a Capillary flow restrictor to use now and I have read in the past it's a good idea to run a adjustable one & a fixed one together to adjust for temp changes for summer & winter.

My question is do I put the adjustable flow restrictor in parallel, or series with each other?

Thanks
Dave

[atvdave]

OK.. I now have more questions..

I went ahead in placed the capillary flow restrictor in series with the adjustable flow restrictor. I opened the adjustable flow restrictor all the way just to see what kind of ratio I would get with my water temp.

I either got a wrong capillary flow restrictor or I'm doing something wrong. I got a ratio of 20:1 (wast:RO/DI).

I let the system run for 10 min before I did any testing but here are my results.

Water temp 51F
PSI with unit shut off 70 psi
PSI in with unit on 46 psi
PSI ofter pre filters 45 psi

TDS supply 171
TDS wast 179
TDS RO 5.3
TDS DI 0.1

My normal PSI when I had my adjustable flow restrictor set at 4:1 was like 70 psi

I know with the temps cold there will be different ratio's but 20:1? and my PSI drop to 46?

Think I may have got a defective capillary flow restrictor or the wrong one?

[cleandrink]

What color is the capillary flow restrictor and where did you put it at in the tubing?

[atvdave]

It was blue in color, and I put it in series with the adjustable valve on my wast line coming from the RO unit.

I opened the valve all the way up just to see what my wast:ro water would be.

[cleandrink]

The capillary flow restrictor should be inline, in the tubing on the end that fits into the membrane housing. The blue is the 75 gpd size restrictor. Do you know what size membrane you have? You have enough water pressure that you will get optimal rejection rates. You can stick a 35 gpd restrictor inline to cut the flow down a lot more if you want.

[rbursek]

From what Jim told me at the Filterguys it is a myth about the different restricters for cold and warmer water. FWIW

[atvdave]

<a href=showthread.php?s=&postid=11873567#post11873567 target=_blank>Originally posted</a> by cleandrink
The capillary flow restrictor should be inline, in the tubing on the end that fits into the membrane housing.

It is, however I don't have it installed into the membrane housing fitting. I have it down stream so I have room for a membrane flush valve.


<a href=showthread.php?s=&postid=11873567#post11873567 target=_blank>Originally posted</a> by cleandrink
The blue is the 75 gpd size restrictor. Do you know what size membrane you have?

Looks like I got the right one. I have the dow 75GPD


<a href=showthread.php?s=&postid=11873567#post11873567 target=_blank>Originally posted</a> by cleandrink
You have enough water pressure that you will get optimal rejection rates.

Yes. Like I said when I have the valve set to a 4:1 ratio I have around 70psi on my RO/DI system. But when I open the valve up and just have the capillary flow restrictor working it drops to 45psi & my ratio goes to 20:1.

This is whats puzzling me. I can under stand a bit more wast for colder water temps but not 500% more wast.


<a href=showthread.php?s=&postid=11873567#post11873567 target=_blank>Originally posted</a> by cleandrink
You can stick a 35 gpd restrictor inline to cut the flow down a lot more if you want.

I'll just use my adjustable valve till I get this taken care of.

[atvdave]

AZ.. you around?

[burton14e7]

What is a flow restrictor for?