How to size CAPILLARY flow restrictor

My system is a 100 GPD RO system with the appropiate fixed CAPILLARY flow restrictor. I am getting 5/1 ratio.

To get a 4/1 ratio using a fixed capillary flow restrictor, will a restrictor for a 75 gal a day system get me more water output?

 

A "smaller" flow restrictor will waste less water, but not necessarily make more product water.

Scott
SpectraPure, Inc.

 

Not sure on the answer to your question but have you considered a booster pump. My new RO/DI is 100gpd with a powered booster pump. It makes water at a 1:1 ratio.

 

I hope you don't prematurely foul your membrane running at such a low waste to product ratio. When you added the booster pump, you should have adjusted the flow restrictor to get at least a 3:1 ratio.

Scott
SpectraPure, Inc.

 

I didn't add the booster pump, it is built in. When you say premature, how premature? I have a couple friends with the same unit and they love it. They have been running it for over 2 years with the same membrane. I have a brand new Filmtec 75 gpd that I got in a club group buy from you guys. I planned to change it out when this one goes bad. I'll change out the restrictor then. Currently it is making about 205 gpd. Is it normal for a booster pump to increase the amount of water that is made? I have it running through an additional DI canister but it comes out of the first it is at 0 tds.

 

You are lucky to be living in an area of the country where the water is not too hard. Here in Arizona, our TDS averages 800ppm and we have to design our systems to handle this excessive hardness. The harder the water, the more waste water is needed to keep the membrane flushed free of that hardness.

If you have 0 coming out of the membrane, I'd guess that your tap water TDS is in the very low 100's.

And, yes, booster pumps will increase the product water production rate. How much pressure is your booster pump making? For a typical membrane to make 205GPD, the pressure would have to be 120 psi, and/or the water would have to be well over 77degF.

Scott
SpectraPure, Inc.

 

Sorry but I meant TDS is 0 out of the first stage of DI. Incoming water is 240 right now. I always run two just as a safety precaution. The system flushes the membrane before each use. I don't have a pressure gauge so I don't know what pressure the booster pump is putting out. This is a 100 gpd membrane. I say 205gpd because I'm filling a 5 gallon container in 40 minutes.

 

Good. 240 TDS is getting close to being too much, but the flushes do help a lot.

Since there are 1440 minutes in a day, and 40 minutes fills a 5 gallon bucket, then 1440 / 40 = 36, and 36 x 5 = 180 GPD, still very good.

Scott

 

Thanks Scott