What are Sizing Flow Restrictors in RO systems?
A flow restrictor is a mechanism found in every reverse osmosis machine that controls the amount of water that flow to the drain.
Flow Restrictors are also known as Flow Controls or Capillaries when it comes to sizing. The flow restrictor should be sized to match the membrane production size in general. Although the drain flow ratio frequently drops as membranes get larger, the flow to drain is normally roughly four times the membrane manufacturing rate.
The importance of flow restrictor sizing
Flow Restrictors maintain the proper ratio of reject (to drain) and permeate (product) flow by applying pressure to the reverse osmosis membrane element.
The fact that membrane production is normally measured in gallons per day (gpd) and flow restrictors are measured in millilitres per minute (mlm), adds to the complexity of comprehending this ratio.
For conversion, multiply (mlm) by 0.38 to get gallons per day as a preliminary estimate!
The inline capillary flow restrictors are shown in the diagram below. These are capillary systems that are installed directly into the drain tube. Simply clip the 1/4" drain tube and insert both ends into the flow restrictor.
The following is a list of membranes and flow restrictors that have been matched as nearly as feasible. One can run the unit a little leaner (with a smaller flow restrictor) than advised if your water is extraordinarily clean with low TDS (total dissolved solids), especially low hardness.
Membrane Size |
Flow Restrictor |
18 gpd |
200 |
25 gpd |
250 |
36 gpd |
250 or 350 |
50 gpd |
420 or 525 |
75 gpd |
525 or 800 |
100 gpd |
800 |
Insert Flow Restrictors in Style
Small flow restrictors are put into the (1/8" X 1/4") elbow that links the drain tube to the membrane vessel in many RO units. Remove the original ‘insert restrictor’ before installing a new capillary inline flow restrictor.
If you're replacing your RO membrane, any of the sizes listed above can be used in a regular membrane housing. Just make sure you replace the flow restrictor as well to match the membrane.
Choose an insert style restrictor that suits both your membrane manufacturing and your fitting style if you're replacing an existing one.Use a ‘Netsol style flow restrictor’ if the tube presses into the drain fitting on your membrane housing; or, if the tube attaches with a plastic nut, use a flow restrictor.
Membrane Size |
Use flow Restrictor |
10 or 12 gpd |
50 gal. |
18 gpd |
70 gal. |
25 gpd |
100 gal. |
36 gpd |
100 or 125 gal. |
50 gpd |
150 or 200 gal. |
75 gpd |
Use a capillary style restrictor |
100 gpd |
Use a capillary style restrictor |
What do we have to offer?
If you want to know more about sizing flow restrictor, then you are at the right place!
You can have an expert solution upon contacting Netsol Water, a leading manufacturer of Industrial and Commercial Water treatment plants (RO Plants) and Wastewater treatment plants, among other services.
Netsol Water is Greater Noida-based leading water & wastewater treatment plant manufacturer. We are industry's most demanding company based on client review and work quality. We are known as best commercial RO plant manufacturers, industrial RO plant manufacturer, sewage treatment plant manufacturer, Water Softener Plant Manufacturers and effluent treatment plant manufacturers. Apart from this 24x7 customer support is our USP. Call on +91-9650608473, or write us at enquiry@netsolwater.com for any support, inquiry or product-purchase related query.