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RO membrane filter
- Thread starter Ontheeyes
- Start date
Wow that is a big pump. What kind of motor are you using for the pump? How are the no name membranes working out for you still?
MEP001
Well-known member
It will increase the flow through the membranes which will let you reduce the reject rate to 1:1, and it may slightly increase the production rate.
Did you ever go with this pump setup? If so. how is it doing for you?
Buckeye Hydro
Active member
Guys - If you do some homework re the RO membranes, pay attention to the pressure spec of the particular membrane you're looking at. For instance:
"Low Energy" membranes are available - and practically speaking you can think of them as "Low Pressure" membranes.
Assuming you have the appropriate pretreatment, understand the minimum concentrate flow, and the expected permeate (RO Water flow) given your pressure and water temperature. Check all that against your concentrate and permeate flow gauges and pump pressure gauge.
Russ
Assuming you have the appropriate pretreatment, understand the minimum concentrate flow, and the expected permeate (RO Water flow) given your pressure and water temperature. Check all that against your concentrate and permeate flow gauges and pump pressure gauge.
Russ
GeorgeFrankie
Banned
You don’t have to buy from Hydro Spray—just make sure any 4"x40" membrane you choose matches the specs. You can likely find a cheaper option elsewhere.
Buckeye Hydro
Active member
The two primary specs you want to match up are diameter and length which you've already done (4" x 40" nominal) and the pressure at which you run the system. For instance, we stock membranes with pressure specs @ 80 psi, 100 psi, 150 psi, and 225 psi.
https://www.buckeyehydro.com/4-diamter-ro-membranes/
We are in the process of stocking some lower cost membranes, which seem to be what many in this industry are hunting for.
You want to buy a membrane that is spec'ed at your typical running pressure or below. In other words, you'd not want to run a 225 psi membrane at 100 psi; but it is fine to run a 100 psi membrane at 225psi. If you exceed the pressure spec on a membrane you'll get better than spec performance. Max operating pressure for these types of membranes are typically very high (e.g., 600 psi) - well above what most fresh water commercial RO's can produce.
Russ
https://www.buckeyehydro.com/4-diamter-ro-membranes/
We are in the process of stocking some lower cost membranes, which seem to be what many in this industry are hunting for.
You want to buy a membrane that is spec'ed at your typical running pressure or below. In other words, you'd not want to run a 225 psi membrane at 100 psi; but it is fine to run a 100 psi membrane at 225psi. If you exceed the pressure spec on a membrane you'll get better than spec performance. Max operating pressure for these types of membranes are typically very high (e.g., 600 psi) - well above what most fresh water commercial RO's can produce.
Russ
Wash Dragon
New member
From what we understand, they are using high-pressure membranes at relatively low pressure, like city water pressure, to increase production.
They said that if they use low-pressure membranes, the production rate would be too low and it would quickly run out of water.
They said that if they use low-pressure membranes, the production rate would be too low and it would quickly run out of water.
Wash Dragon
New member
Wouldn't operating above the rated pressure damage the membrane?
From what I know, it's actually the opposite — running a low-pressure membrane at high pressure tends to shorten its lifespan.
I’ve heard that using a high-pressure-rated membrane at lower pressure results in lower efficiency, but still provides more permeate than a low-pressure membrane under the same conditions.
Buckeye Hydro
Active member
The devil is in the details here. What is your pump output pressure? What membranes are installed?
When a manufacturer provides a temperature and pressure spec on a given membrane, nothing says those conditions are "ideal." They are just the conditions provided to the membrane during testing, and those conditions resulted in x gals per day production of permeate (RO water). Let's say the spec pressure is 150 psi: if you run it at 180 psi, the membrane performance will be better - both in terms of amount of permeate produced, and purity of the permeate. If you check into the fine print, max recommended pressure might be something like 600 psi.
Hate to say it, but most often when vendors sell someone something like a 225 psi 4040 membrane designed to produce ~2600 gpd, and tell you it's ok to run it at your pump's max of let's say 110 psi, (we even see some vendors suggesting unsuspecting customers run these membranes at line pressure [typically 50 to 60 psi]) the primary beneficiary of that sale is the vendor. They sold you a membrane much more expensive than need be, and it is not well matched to your system.
When a manufacturer provides a temperature and pressure spec on a given membrane, nothing says those conditions are "ideal." They are just the conditions provided to the membrane during testing, and those conditions resulted in x gals per day production of permeate (RO water). Let's say the spec pressure is 150 psi: if you run it at 180 psi, the membrane performance will be better - both in terms of amount of permeate produced, and purity of the permeate. If you check into the fine print, max recommended pressure might be something like 600 psi.
Hate to say it, but most often when vendors sell someone something like a 225 psi 4040 membrane designed to produce ~2600 gpd, and tell you it's ok to run it at your pump's max of let's say 110 psi, (we even see some vendors suggesting unsuspecting customers run these membranes at line pressure [typically 50 to 60 psi]) the primary beneficiary of that sale is the vendor. They sold you a membrane much more expensive than need be, and it is not well matched to your system.
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