Flow restrictor on homemade ro

[diesel79james]

I was wondering if anyone has tried a flow restrictor on a homemade r o in place of the needle value and if so what one are you guys using. My concentrate seems to slow down after I run the r o for a while and I have to loosen up the needle value. I just thought that a flow restrictor would be more consistent. Any help would be greatly appreciated thank you.

[Urban Sugarmaker]

I think you can use a gate valve. I know others have done it, and they are far less expensive than needle valves.

[diesel79james]

I guess I forgot to mention that the r o is a small scale residential r o with 150 gpd membranes and 1/4 inch line

[maple flats]

The flow on that at just over 6 GPH might be too little to use anything but a needle valve. A unit of higher flow might well be able to use a cheaper alternative but at 6 GPH the valve will need to be able to do some real "fine tuning" and you would not be able to get away using a flow restrictor for lack of adjustability.

[bowhunter]

You should use a needle valve. Gate valves and ball valves are terrible for pressure control. A flow restrictor might work on water where fouling of the membrane is very, very slow, but a membrane processing maple sap will foul substantially over just a couple of hours and you must be able to adjust the flow using the needle valve. Not sure why you concentrate flow is dropping off, but in any case the needle valve is needed.