RODI - Are these check valves?

[Lori_inFL]

I am adding a new booster pump and auto shut off float switch to an RODI I bought on FB mktplc. I have read that I need a check valve prio to the DI filters. I have a new inline switch but there is a thing on the BRS site sowing a picture of L-shaped switches that may be installed as part of the RO membranes cartridges. But I can't blow up the illustration to see what they look like as opposed to other Murdock fittings. Can someone tell me if these are check valves on the ROs. Or if you can't tell, would there be an issue if I added the in-line after the Y joining the 2 lines from the ROs?

On the in-line am I correct in assuming the red side is the output end so the water won't travel from that side to the other.

Thanks in advance!

 

[UncommonSense]

The check valves are on the side not pictured with the threaded/knurled caps for the RO membrane housings!

They are a check valve built into a NPT threaded to push connect elbow, directly into the RO membrane housing!

Mur-lok Elbow Check Valve 1/8" Male NPT x 1/4" Push Connect

Check valves only allow water to flow one direction. 1/8" Male NPT x 1/4" Push Connect elbow check valves are typically used on the product water output of RO membrane housings to protect from back pressure and allow auto shut off valves to operate correctly.

www.bulkreefsupply.com

 

[Lori_inFL]

These look like regular elbows to me.

 

[UncommonSense]

Ah, they aren’t though! If you were doing a service on your RO system, and replacing membranes; you’d see that the part of the elbow threaded inside the membrane housing cap has what appears to be a tire Schrader valve in the end of it!

Note the little metal part sticking out of the threaded end of the elbow in my BRS link!

 

[Lori_inFL]

Oh, I see that now. But i am confused because
https://www.bulkreefsupply.com/content/post/Installing-an-auto-shut-off-valve
says the check valve needs to be on the filtered water end and the illustration shows it on the rounded non-lid end.

Does it need another before the DI?

 

[Jekyl]

The valve on top is for flushing. I usually run mine for a few minutes before switching to make the water I use.

 

[UncommonSense]

Oh, I see that now. But i am confused because
https://www.bulkreefsupply.com/content/post/Installing-an-auto-shut-off-valve
says the check valve needs to be on the filtered water end and the illustration shows it on the rounded non-lid end.

Does it need another before the DI?

Interesting! This must be a newer addition!

All it should theoretically do is prevent RO product water from feeding back into the RO membrane if the product line is pressurized and the system looses pressure simultaneously…

You definitely don’t need a check valve before the DI stage, that’s all very straightforward, and not typically left pressurized!

 

[Lori_inFL]

Msybe it needs one so if/when the float valve trips the DI(s) would be pressurized and back flow into the RO?

 

[UncommonSense]

Msybe it needs one so if/when the float valve trips the DI(s) would be pressurized and back flow into the RO?

Nah, water can’t go backwards unless there’s a pressure drop upstream… so this secondary check valve must be to prevent just that!

I know I’ve never needed it on my BRS 6-stage 150gpd unit in over a decade!

 

[Lori_inFL]

That makes sense. Thanks. If it acts squirrely, (maybe i should say fishy) I can always add it since now I have one in the spare parts dept.

 

[UncommonSense]

After further consideration; here’s what I’m curious about…

Check valves inherently only work in one direction… yet the above diagram indicates that they have check valves on both ends of the RO membrane, flowing in opposite directions….

As far as I know, BRS doesn’t have two different part numbers for “push” vs “pull” direction elbow check valves… so only the in-line check valve post-membrane would make sense…

 

[KStatefan]

I am adding a new booster pump and auto shut off float switch to an RODI I bought on FB mktplc. I have read that I need a check valve prio to the DI filters. I have a new inline switch but there is a thing on the BRS site sowing a picture of L-shaped switches that may be installed as part of the RO membranes cartridges. But I can't blow up the illustration to see what they look like as opposed to other Murdock fittings. Can someone tell me if these are check valves on the ROs. Or if you can't tell, would there be an issue if I added the in-line after the Y joining the 2 lines from the ROs?

On the in-line am I correct in assuming the red side is the output end so the water won't travel from that side to the other.

Thanks in advance!

Check valve should be at the permeate output of the membrane witch is the blue lines in your picture.
The input on the membrane is the end with just one fitting . On your system the waste from the first membrane goes to the second membrane.

 

[Lori_inFL]

After further consideration; here’s what I’m curious about…

Check valves inherently only work in one direction… yet the above diagram indicates that they have check valves on both ends of the RO membrane, flowing in opposite directions….

As far as I know, BRS doesn’t have two different part numbers for “push” vs “pull” direction elbow check valves… so only the in-line check valve post-membrane would make sense…

Thank you for thinking about my situation after i adjourned for the night. It helps this noob confidence when my thinking is vindicated!

 

[Lori_inFL]

I am adding a new booster pump and auto shut off float switch to an RODI I bought on FB mktplc. I have read that I need a check valve prio to the DI filters. I have a new inline switch but there is a thing on the BRS site sowing a picture of L-shaped switches that may be installed as part of the RO membranes cartridges. But I can't blow up the illustration to see what they look like as opposed to other Murdock fittings. Can someone tell me if these are check valves on the ROs. Or if you can't tell, would there be an issue if I added the in-line after the Y joining the 2 lines from the ROs?

On the in-line am I correct in assuming the red side is the output end so the water won't travel from that side to the other.

Thanks in advance!

Check valve should be at the permeate output of the membrane witch is the blue lines in your picture.
The input on the membrane is the end with just one fitting . On your system the waste from the first membrane goes to the second membrane.

Thank you for confirming my initial thinking. This Rodi stuff is somewhat complicated and new to me. Really not my initial thinking; more like after several hours of surfing and looking for a comparable schematic!