Flow Restrictor with manual flush valve 1/4″.

Add to your existing Reverse osmosis system to give you the ability to flush the membrane to help extend serviceable life of the membrane.

Flow Restrictor with Manual Flush Valve


Available on backorder


 Description-Flow Restrictor with manual flush valve

Every reverse osmosis unit has a device called a flow restrictor that determines the amount of water that flows to drain. In general, the flow restrictor must be sized to fit the membrane production size. The flow to drain is usually about four times the membrane production rating, although the drain flow ratio often decreases a bit as membranes get larger. The flow restrictor also provides back pressure within the membrane in order to maintain a specific permeate/waste flow.

Part of the difficulty in understanding this ratio is that membrane production is usually given in gallons per day (gpd), while flow restrictors are usually sized in milliliters per minute (mlm). To convert, multiply mlm by .38 and the result, roughly, will be gallons per day.

Specifications- Flow restrictor with flush valve

-300 ML/Min(for other sizes please contact us )

– build in flushing option

-Recommended for 50 GPD Reverse Osmosis membranes.

– In/Out Ports 1/4″ Tube OD – 0.170″ ID tube

– Compatible with quick connect and compression fittings

Quick connect fittings for 1/4″ tubing included.

Turn the black knob to flow direction ( to right side) once every 3 to 6  months for 5 minutes, in order to enable the valve Passing fast & high speed flow of water over the membrane surface and clean off any remains or scale that would cause clogging and effects your membrane life.

OD = outside diameter

ID = inside diameter


General Guideline for Flow restrictor sizing-

Below Is indicative sizing only and membrane manufacturer guidelines, actual water conditions and parameters should be considered.   For instance, in areas with hard water like Perth or Brisbane we would recommend a minimum waste:pure water ratio of 4 ( ideally 5) .


RO Membrane Size
(Gallons Per Day)
Use Flow Restrictor
(ML Per Minute)
8-20 GPD 150
21-25 GPD 250
36 GPD 350
50 GPD 500
75 GPD 750
100 GPD 1000
150 GPD 1200


flow restrictor08022


Example Calculation:  You have a 80 gpd membrane, have relatively poor water conditions including hard water(like in Perth or Brisbane)  and want to maintain a minimum waste :pure water ratio of 4: 1.

80 GPD = 80/24 GPH =3.3 GPH = 0.056 GPM.

0.056 GPM =021 Litres/min or 210 ml/min .

Hence flow restrictor should be sized 210 x 4 ml/min equating to approximately 800 ml/min.


Additional information

Weight 0.1 kg
Dimensions 6 x 6 x 5