How much water pressure should a rodi unit have?
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TJ's Reef
Valuable Member
They are more effective with higher psi, mine is running before my homes PRV so somewhere between 85-91 psi usually. I believe that the booster pumps they sell to go with run upwards of 85psi ???
Cheers, Todd
Cheers, Todd
As much as you can give it, membranes love pressure and perform better at higher pressures.
The weak point on some no name or what I consider EBay type sytem are thefillings and housings which may not be Uniform Plumbing Code or ANSI/NSF tested and rated and may not stand up to the usual 125 psi working pressure tha name brand fittings and sytems will take.
I have been running my current Spectrapure system with a booster pump set at 95-100 psi for about 5.5 years now and it has never posed a problem. At that pressure Im getting over 125 GPD out of a 75 GPD membrane and at 99.4% rejection rate to this day.
The weak point on some no name or what I consider EBay type sytem are thefillings and housings which may not be Uniform Plumbing Code or ANSI/NSF tested and rated and may not stand up to the usual 125 psi working pressure tha name brand fittings and sytems will take.
I have been running my current Spectrapure system with a booster pump set at 95-100 psi for about 5.5 years now and it has never posed a problem. At that pressure Im getting over 125 GPD out of a 75 GPD membrane and at 99.4% rejection rate to this day.
Nice
Plumbing code calls for no more than 80 psi residential line pressure.
That said, RO membranes function better at higher pressures. Filmtec membranes for instance have a max pressure rating of 300 psi. But, not all components in any RODI system can handle pressure that high. The weakest link in terms of ability to handle pressure is typically the clear filter housings. Some clear housings are better than others in this regard (as rat man said).
This is one of the things we think about when we hear people say "all rodi systems are alike." Well, no, they really aren't!
Also - if you're going to add a booster pump, it's best to plumb it in AFTER the prefilter housings to avoid exposing them to the elevated pressure.
Russ
That said, RO membranes function better at higher pressures. Filmtec membranes for instance have a max pressure rating of 300 psi. But, not all components in any RODI system can handle pressure that high. The weakest link in terms of ability to handle pressure is typically the clear filter housings. Some clear housings are better than others in this regard (as rat man said).
This is one of the things we think about when we hear people say "all rodi systems are alike." Well, no, they really aren't!
Also - if you're going to add a booster pump, it's best to plumb it in AFTER the prefilter housings to avoid exposing them to the elevated pressure.
Russ
Well, not really.
Membrane manufacturers test their membranes under a specific set of criteria, including pressure, temperature, feedwater TDS, recovery, etc. Most manufacturers use a pressure of 60 psi when they test their membranes. One manufacturer (Filmtec) uses 50 psi. Nothing says these are "optimum" - this pressure is just one in a set of conditions under which their membranes are tested.
Russ
Membrane manufacturers test their membranes under a specific set of criteria, including pressure, temperature, feedwater TDS, recovery, etc. Most manufacturers use a pressure of 60 psi when they test their membranes. One manufacturer (Filmtec) uses 50 psi. Nothing says these are "optimum" - this pressure is just one in a set of conditions under which their membranes are tested.
Russ
No.
The mebrane industry had to come up with some standards so they could test on brand or size against another and chose 60 psi and 77 degrees F. They are not the optimum pressure or temperature, in fact far from it. It gives them a way to compare aDow filmtec to a GE to a Koch to an Applied etc. Its just a standard, not a must and higher pressure is better just as colder than 77 degrees treats better and gives you lower TDS.
The mebrane industry had to come up with some standards so they could test on brand or size against another and chose 60 psi and 77 degrees F. They are not the optimum pressure or temperature, in fact far from it. It gives them a way to compare aDow filmtec to a GE to a Koch to an Applied etc. Its just a standard, not a must and higher pressure is better just as colder than 77 degrees treats better and gives you lower TDS.
ReefPiracy
Active Member
Well Said. I need to get a booster pump ASAP!
Mine is between the carbon block and the RO membrane too. No big deal as long as the pump has some form of sediment protection.
Fengxzhang
Community Member
Careful running higher pressure. I had between 40-55 PSI water pressure and i was going through DI resin like crazy. I have since upgraded from a 50 GPD to 100 GPD and added a booster pump. The booster pump put out about 110PSI. When I can came after about a week, I found one of the canisters that was holding carbon busted at the seam. Since I have dialed the pressure to 75 PSI. I have "made" over 500 gallons of water over the last 3 weeks and my DI resin is less than 1/5 expended.
Right. So as long as your going to take the 20 minutes necessary to set the pump up, might as well put it in the "best" location - after the last prefilter and a strainer, but before a liquid filled pressure gauge and the RO membrane "in" port.
Russ
Russ
RO membranes are more efficient at higher pressures, I have run 95-100 for almost 6 years now and get 99.4% rejection rate. At lower pressure my membrane does not work as well and DI does not last nearly as long.
The weak links are inferior components. Reputable vendors sell canisters, fittings and filters tht have been tested and rated by agencies such as the ANSI/NSF and UPC and can take the higher operating pressures. Many ebay type vendors sell imported components that have not been subjected to the very expensive and time consuming testing and certification process so you really do get what you pay for. Stick with reputable vendors with a documented history, you may spend a couple more $$ upfront but it will pay off over the life of the system.
Usually when you hear about a failure its a low end imported system and lower quality filters. Failures with quality systems and components are rare.
The weak links are inferior components. Reputable vendors sell canisters, fittings and filters tht have been tested and rated by agencies such as the ANSI/NSF and UPC and can take the higher operating pressures. Many ebay type vendors sell imported components that have not been subjected to the very expensive and time consuming testing and certification process so you really do get what you pay for. Stick with reputable vendors with a documented history, you may spend a couple more $$ upfront but it will pay off over the life of the system.
Usually when you hear about a failure its a low end imported system and lower quality filters. Failures with quality systems and components are rare.
joeyhatch11
Well-Known Member
I've been running mine at 125psi for 6 months now. Running a 1:1 ratio. DI hasn't changed color, getting 1-2 TDS out of membrane and 0 out of DI. Lovin it!!!
Be careful. The proverbial 4 to 1 ratio is there for a reason. Unless you have VERY soft water, and/or flush your membrane very frequently, you have inadequate waste water (better thought of as "flush water"). It's this water that flushes all the stuff away from the membrane that doesn't go through to the purified water side. Inadequate waste water (a.k.a. excessive recovery) = short membrane life.
Russ
Russ
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Joey, what is your water hardness and your tap TDS? A 1:1 waste ratio will plug a membrane very quickly since you do not have sufficient brine or waste flow. ALL membranes must be flushed, there is no way to ge taround that period. If someone told you any different they are uninformed and mistaken. It will cost you in short membrane life.
Even the so called "Flush Kits" have limited if any and certainly no documented proff they do anything besides lighten your wallet and give you a warm fuzzy feeling. I find them a waste of good hard earned money and would use a good proven, well documented waste ratio any day over a flush kit. Membranes MUST be flushed when in use or they fail.
Even the so called "Flush Kits" have limited if any and certainly no documented proff they do anything besides lighten your wallet and give you a warm fuzzy feeling. I find them a waste of good hard earned money and would use a good proven, well documented waste ratio any day over a flush kit. Membranes MUST be flushed when in use or they fail.
GrampaDon
Active Member
A good case for when I add to my system ^ And for reference what temp is your input AZ ?
Myself I use a 2 into 1 with valves so I can adjust the temp to 73-77 And that gives me 40-50g in 12hrs with 60psi at the gauge.
Its a Buckeye Supply unit.
I cringe whenever I hear about someone blending or tempering hot and cold water! Remember being in a nice warm shower and someone flushed the toilet or started the washing machine? You got your tush scalded. The same thing happens to a RO membrane which cannot stand anything over 113 degrees or the melt the TFC fabric and are toast. Never blend the water! Besides, colder water is more dense so fewer contaminants pass through the membrane and your rejection rate or RO only TDS will be lower. this means your DI will last longer and the overall cost of operation and ownership will be lower. Do not raise the temperature if you want more water, get a RO booster pump such as the Aquatec 8800 and raise the pressure, it is much more efficient and you will have even better rejection rate.
My input water varies between 56 degrees and 68 degrees but even here in Phoenix is usually on the colder side since I am in the north end of town closer to the Lake Pleasant impound an treatment plant. They designed intakes at several different levels to get the best temperature, dissolved oxygen level and water quality. I wouldn't even think about warming it, raising my RO TDS and shortening my DI life. If I want more water I raise the pressure. You are doing yourself a disservice not a favor.
My input water varies between 56 degrees and 68 degrees but even here in Phoenix is usually on the colder side since I am in the north end of town closer to the Lake Pleasant impound an treatment plant. They designed intakes at several different levels to get the best temperature, dissolved oxygen level and water quality. I wouldn't even think about warming it, raising my RO TDS and shortening my DI life. If I want more water I raise the pressure. You are doing yourself a disservice not a favor.
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