RO/DI Servicing Question

[Rcpilot]

I just got a new RO membrane, DI resin, carbon blocks and sediment filter for my RO unit. I also added a 2nd membrane to reduce waste water.

I don't want to smoke my new DI resin.

I disconnected my output line from the membranes and I'm dumping the first 5g or 10g into a bucket without letting it pass through the DI resin.

Is that long enough to flush the membranes and carbon blocks before I connect to the DI cartridges and begin running normal operation?

 

[projectx]

Which unit do you have?

 

[Rcpilot]

It's a Filter Direct RD102

http://filterdirect.com/product_info.php?cPath=21&products_id=29

I added a 2nd 100gpd membrane and a new restrictor valve today.

Just curious to see how long other people run their unit with a new membrane before pumping the water into their actual storage tank. How much of it do you pump down the drain to "wash" the new membranes?

 

[dv3]

check the FAQ's on buckeye field supply

 

[Rcpilot]

Thanks. That helped a lot.

I'm wondering about my new flow restrictor now. The original had a 600 printed on it and that was for a single 100gph membrane. But I added a 2nd RO membrane and the new restrictor says 800 on it. Not sure how to read that or what those numbers mean.

I was hoping that by adding a 2nd membrane I would reduce my waste water. I guess I expected the waste water to trickle out, but that doesn't make sense now that I think about it. You still need 4:1 to wash the membranes properly.

I am getting more clean water out of the RO unit with the 2nd membrane. It's almost streaming out enough to put out a small fire. But the waste water line is gushing out under very high pressure. Seams almost like it's dumping even MORE water down the drain now.

Anybody an expert on these restrictors?

I can go to reef central for more exposure, but I hate that place. Was hoping somebody local could help.

 

[dv3]

i think your best just playing around with it till you find the best configuration ...thats what i did anyhow

 

[Zooid]

I believe the 600 means 600 milliliters per minute and the 800 means 800 milliliters per minute.
Since the flow restrictor is normally placed on the waste water line, it should restrict the amount of wastewater to 600 or 800 ml/min.
800 will allow more flow to the drain and may reduce your RO output because there will be less pressure at the membrane.
You have to be careful when selecting a flow restrictor because if you choose one that allows very little flow to the drain, the membrane
may not be able to handle the pressure and will rupture.

 

[Zooid]

I believe the 600 means 600 milliliters per minute and the 800 means 800 milliliters per minute.
Since the flow restrictor is normally placed on the waste water line, it should restrict the amount of wastewater to 600 or 800 ml/min.
800 will allow more flow to the drain and may reduce your RO output because there will be less pressure at the membrane.
You have to be careful when selecting a flow restrictor because if you choose one that allows very little flow to the drain, the membrane
may not be able to handle the pressure and will rupture.

http://www.uswatersystems.com/shop/categories/Reverse-Osmosis-Parts,-Pumps,-Tanks-%26-Accessories/Check-Valves-%26-Flow-Restrictors/
http://www.uswatersystems.com/shop/products/Capillary-Flow-Restrictor-%2d-800-Mil.html

It doesn't look like either one of those are out of the normal range for a 100gpd.
Are your running the membranes one after the other or are you sending the wastewater from one membrane to the other membrane?

​

 

[Rcpilot]

The membranes are in-line. Waste water from #1 goes to input on #2 and then the final waste water is routed through the restrictor.

I have a 600 restrictor here. Could put that on instead. But it would reduce the amount of flushing across both membranes.

What I've basically done, is create a 200gpd RO unit. In reality, the waste water must be MORE than when I started with just a single membrane. Takes twice as much water to flush a 200gpd membrane. :wall:

Anybody need a barely used 100gpd General Electric TFM-100 membrane?

 

[dv3]

your waste water should still he less than if you were using a single 200gpd membrane

 

[othercents]

I thought when one membrane flowed into the other you used the same size restrictor, but it would double the output of the RO water. The restrictor only controls the waste water flow over the last membrane. The first membrane would flow faster based on restrictor and clean water coming out of the second RO unit. This is all dependent on water pressure. You still need to maintain the manufacturer recommended pressure. The second 800 restrictor could be used between the two units to make sure the flow is consistent through the first membrane while the 600 restrictor used after the last RO membrane.

BTW. it takes the same amount of flow to flush a 100GPD membrane regardless if there is 1 or 20 membranes in a row. The last membrane will be set at the minimum flow rate of 600 while the other membranes would be flushing at a faster rate. If you place two membranes side by side both being feed by the same line, then you would need a restrictor on each at 600 making 1200 flow of total waste.

 

[space]

How has the unit worked out?