RODI Questions/Concerns - flow restrictor and pressure gauge

[Cantusaurus]

Hi, I have been in the hobby for over 3 years and have been using RODI. But I have been doing so without fully understanding certain things. Over the past couple weeks I worked to change that, and I made adjustments in order to help with preserving filters etc.
the changes mostly involves making additional flushing features.

But I lost the flow restrictor on the unit. It was a little inline one that went into the tubing.
Is that necessary? and should I buy a new one asap? i tested all the changes I made and used the valve to limit the water passing out of the waste line.

But also i don’t think I installed the pressure gauge correctly since it’s not moving at all. I heard it’s best to put it after the filter membrane in order to see if it’s getting clogged. But I probably did something wrong.

I would greatly appreciate any help.

 

[Gtinnel]

Usually the pressure gauge goes on the inlet side before the membrane and it looks like you’ve put it after the membrane.
I’ve never used a valve in place of a flow restrictor but I can’t see any reason it wouldn’t work. I would still recommend getting an actual flow restrictor.

 

[Cantusaurus]

Usually the pressure gauge goes on the inlet side before the membrane and it looks like you’ve put it after the membrane.
I’ve never used a valve in place of a flow restrictor but I can’t see any reason it wouldn’t work. I would still recommend getting an actual flow restrictor.

Ok thank you.
Yeah I just heard it’s good to have it after the membrane in order to monitor it getting clogged. But I think some people usually have two. But I guess maybe I shouldn’t worry about that, and place it where you recommend.
And yeah I’ll definitely get a flow restrictor just in case. I just have the valves there as a redundancy for the flushing system I have.

 

[homer1475]

Pressure gauge should be before the membrane. I don't think shutoff valves will replace a flow restrictor. Could be why your not seeing any pressure after the membrane.

 

[Gtinnel]

Ok thank you.
Yeah I just heard it’s good to have it after the membrane in order to monitor it getting clogged. But I think some people usually have two. But I guess maybe I shouldn’t worry about that, and place it where you recommend.
And yeah I’ll definitely get a flow restrictor just in case. I just have the valves there as a redundancy for the flushing system I have.

Usually you hear about using the pressure gauge to tell when the prefilters get clogged not the membrane. I don’t know what the pressure on the permeate side of the membrane will be but I doubt it is very much, and the see no reason to want to know it.

 

[KStatefan]

The presure after the membrane on the permeate side will be next to nothing. That pressure difference is what makes the reverse osmosis work. You tell when your membrane needs to be replaced by watching the rejection rate.

You will not get enough control with the ball valve in place of the orifice tube

 

[Woodyman]

As previously stated get yourself a proper flow restrictor, sized appropriately, and then switch the location of that pressure gauge.

 

[Cantusaurus]

Ok. Thank you everyone for your advice/information. I appreciate it. I bought an Aquatic Life 200CC/ML flow restrictor. I'm not sure what that means though as far as the number associated with it. There are other number values, but I got the smallest one. I think I can return it and replace it for another one if needed.

EDIT**
I looked into it and I screwed up. I should've gone for the 420 - 800 sizes instead. I'll just return the 200 I guess.