New RO Membrane / flushing process

[wsoldier]

So I'm confused about instructions for flushing a new RO membrane (I'm using a BRS 6 stage system). Even BRS suggests running the output just as you normally would (flush valve OFF) and dumping the "clean" output water after a few gallons.

My question is, why isn't using the flush valve sufficient enough (I thought that was the point)? Can I not just hook up the membrane directly to flush as pictured?

Thanks.

 

[KStatefan]

You need water going thru the membrane to get the preservative out.

 

[wsoldier]

You need water going thru the membrane to get the preservative out.

So what is the purpose the flush valve then during normal operation if it's bypassing the membrane?

 

[wsoldier]

Also in theory, I could just connect a closed valve to the flush output line (black) then to force the membrane I suppose.

 

[Woodyman]

So what is the purpose the flush valve then during normal operation if it's bypassing the membrane?

The flush is to remove sediment/deposits from the membrane to prolong the useful life of the membrane.

 

[Woodyman]

You need water going thru the membrane to get the preservative out.

This, some take longer than others and you should flush at least 30 minutes generally, but it could be longer depending on the actual membrane purchased.

 

[Woodyman]

Also in theory, I could just connect a closed valve to the flush output line (black) then to force the membrane I suppose.

Why would you want to do this?

Just flush it in bypass for a few minutes, then close the bypass and produce RO as normal. During this time (30+ minutes) dump the RO to drain (disconnect your DI stages so you don't burn resin).

After the preservative has been flushed reconnect as normal. While your hooking back up the DI open the bypass flush (do this for ~30+ seconds).

After you get it reconnected close the bypass valve and then run water as normal through the whole system.

Discard the first 1-2 gallons and then your good to go like normal (This step could be avoided, but is a best practice).

 

[wsoldier]

So that's really my question... if flushing with the bypass open is good enough, why does BRS suggest that you just dump the water output w/ empty di resin?

 

[Woodyman]

So that's really my question... if flushing with the bypass open is good enough, why does BRS suggest that you just dump the water output w/ empty di resin?

Flushing with the bypass open will not force water through the membrane and flush out the preservative.

RO membranes operate on pressure, in order to get permeate production you need pressure to force water through the membrane and out. Depending on the specific membrane you purchased it will have a minimum and maximum pressure rating. If you don't send water through the membrane you will not flush out the preservative.

Also depending on the amount of preservative it may flush out quickly or take longer. The longer and more preservative you send to your DI the more resin you burn through.

BRS doesn't care if you flush with your DI installed or not, but if you leave it installed you burn through resin faster. That just means you'll buy more.

If you don't want to bypass your DI after changing the membrane it's not required, but it will save you from depleting your resin with the preservative that will subsequently be sent through DI as you purge the new membrane.

 

[Buckeye Hydro]

Rinse up a new membrane with the concentrate (aka waste water) tube and flow restrictor in place, and the flush valve closed.

 

[wsoldier]

Rinse up a new membrane with the concentrate (aka waste water) tube and flow restrictor in place, and the flush valve closed.

Thanks that's what I ended up doing.