R.O. system problem

[DMorton]

I have inherited a problem at a 6-ss and 2-iba wash I have started working at. I'm completely new to this industry and have enjoyed learning about it except for the R.O. system problem that wont go away.

I don't know the manufacture of the system and believe it is a combination of a couple systems. I have replaced the media tank with new media, new membranes, new pre-filter. Pressure is running at 125 psi, the R.O. to reject water ratio is 40% good to 60% reject to get the best TDS number at this time (80). Where do I look next?
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[MEP001]

It could be that one of the three membranes is defective. You should be getting a better TDS reading than 80.

Have you tried more than one TDS meter? Have you tested it by washing a car and letting it air dry and looking for spots?

 

[DMorton]

I have switched out membranes with the old ones still in good shape, one at a time. I'm testing with a new tds meter w/temperature compensation and the old one at the same time. I do get more water spots than I like on a air dried car.

 

[MEP001]

Have you replaced all three membranes or did you try one new one in each housing? If you replaced them all, you might try to get a sample from each membrane. There's probably a plug in the center of the cap at the other end - there's no pressure on the product side there so you could loosen them and reinstall hand-tight, then run the system for 10-15 minutes or until the reading stabilizes, then loosen each one to get a sample to test.

 

[cantbreak80]

It appears you have (3) 4”x40” membranes which correlates to a 4,500 Gal/Day RO system. Unless you are using “cold” (brackish) water membranes, to produce that volume of permeate, the feed water needs to be approximately 77⁰F.

In my experience, 175-200 psi is required to achieve permeate TDS equal to the specifications.

Turn the concentrate control valve until the designated permeate flow is acquired. For example, a 4500 GPD system should be adjusted until it produces about 3.125 GPM of permeate flow. The concentrate pressure will increase as the concentrate control valve is closed. The exact operating pressure may vary depending on the temperature and TDS of your feed water.

Additionally, new membranes are typically full of preservative which may contaminate the permeate storage tank. New membranes installations should be flushed to drain for one hour at 50 psi before putting the system in service.

To produce "invisibility", the magic number for TDS is <50ppm.

 

[MEP001]

I know "they" say <50 but in my experience and opinion anything above 30 is intolerable.

 

[Earl Weiss]

FWIW I took over an SS with the spot free not working. Never got it working because I thought th benefit did not justify the cost.

I still think that way.

 

[MEP001]

As many customers as I've seen spend over five minutes with the spot-free, I wouldn't ever run a SS without it.

 

[cantbreak80]

Mep001, Just repeating what "they" say.

Earl, I've had way too many customers mention their "affection" for my SFR. Regardless of maintenance/repair costs, it's a keeper!

 

[MEP001]

Mep001, Just repeating what "they" say.

I figured, but "they" aren't the ones with customers griping about spots when the TDS reads just below 50.

 

[Earl Weiss]

Mep001, Just repeating what "they" say.

Earl, I've had way too many customers mention their "affection" for my SFR. Regardless of maintenance/repair costs, it's a keeper!

I understand. I note other operators have said how much use the SFR gets. Not sure if this means overall time useage increases or if instead they use my HP and Wax for the rinse. Had a D& S distributer try to get it going. Replaced parts, cost me about $2500 and said I might need another $10K in pars and labor. Curiously I have a competitor about a 1.5 Miles away and 2 others about 6 miles away. Others farther. To date I have never had someone say "Hey, why don't you have spot free like those other guys?"

 

[Ghetto Wash]

Are you checking TDS in the storage tank or the output from the membranes before the tank. Something could be contaminating the tank.

 

[MEP001]

Had a D& S distributer try to get it going. Replaced parts, cost me about $2500 and said I might need another $10K in pars and labor.

Either you have one hell of an RO system or they were trying to screw you. I could put together an RO system with three membranes, a 450 PSI delivery system and pump for an auto for way less than $10,000.

 

[DMorton]

It appears you have (3) 4”x40” membranes which correlates to a 4,500 Gal/Day RO system. Unless you are using “cold” (brackish) water membranes, to produce that volume of permeate, the feed water needs to be approximately 77⁰F.

In my experience, 175-200 psi is required to achieve permeate TDS equal to the specifications.

Turn the concentrate control valve until the designated permeate flow is acquired. For example, a 4500 GPD system should be adjusted until it produces about 3.125 GPM of permeate flow. The concentrate pressure will increase as the concentrate control valve is closed. The exact operating pressure may vary depending on the temperature and TDS of your feed water.

Additionally, new membranes are typically full of preservative which may contaminate the permeate storage tank. New membranes installations should be flushed to drain for one hour at 50 psi before putting the system in service.

To produce "invisibility", the magic number for TDS is <50ppm.

I will adjust system to this tomorrow if possible on the unit. I check TDS before it mixes with the storage tank.

 

[DMorton]

I appreciate all the help and direction from everyone. I have resolved the problem, I disassembled the the whole membrane system today to see what I could find out of place and luck have it I found one of two o-rings that seal the membrane to the bottom canister head on the last canister I took apart was torn. So now everything has new o-rings and I was immediately reading 0 PPM. So a few hours and $3 worth of o-rings I have my service back.

 

[cantbreak80]

Good for you!!!
And just think...you saved $2,497 by not using Earl's D&S distributor!