Reverse Osmosis Membrane Sizing & Upgrade. Inline Polishing Filter SizingHow to identify the membrane capacity in your Reverse Osmosis RO water filter system and instructions on how to upgrade to a higher capacity Reverse Osmosis RO Membrane.
Osmosis Membrane Sizing & Upgrade. Inline Polishing Filter Sizing
This Guide is intended for customers who have a Standard type Reverse Osmosis System like the one pictured here.
If you have a proprietary system such as Hydrotech, Microline, etc., the basic way to size your membrane and how to upgrade apply, it's just the Drain Flow Restrictor you use is different from the one we describe here.
Some Reverse Osmosis Systems
are available with different capacity RO Membranes and we are often asked
by customers "Which membrane does my system use?" and "How do I upgrade
to a higher capacity membrane?". On this page we explain the mysteries
of the RO Membrane and how you can quickly determine which membrane your
system currently uses.
Many times, the membrane type and capacity are written on the membrane housing itself.
Type of Membrane
CTA membranes are usually have a capacity of 16 GPD (Gallons Per Day) or less.
TFC (TFM) membranes for residential use are now available at up to 150 GPD.
If your system does not have a label which tells you which type membrane you have, you may have to remove the membrane and look on the label.
Why is this important? To operate efficiently, RO Membranes are matched to the proper size Drain Flow Restrictor. The RO Membrane and Drain Flow Restrictor must be matched to keep the proper balance between waste water and pure water. Mismatching can either cause excessive waste to the drain or premature membrane fouling.
There are two ways to determine the membrane capacity of your system. One is to remove the membrane from the RO housing and look at the label. The label should tell you the membrane Type and Capacity.
The other is to look at the membrane Drain Flow Restrictor. Most standard RO Systems use an inline Drain Flow Restrictor like the one pictured here. Although not shown in this picture, the Drain Flow Restrictor has a number on it such as 150, 200, 250, etc.
As the Drain
Flow Restrictor is sized to the Membrane Capacity, all you need
to do is match this number to the chart and you will know the capacity
of the membrane your system is currently using.
How Do I Upgrade To A Higher Capacity Membrane?
This is the easy part. As we mentioned, the RO Membrane and Drain Flow Restrictor are matched. To upgrade to a higher capacity membrane, all you need to do is make sure you also replace the Drain Flow Restrictor to match the new membrane.
Inline Polishing Filters are available in two configurations. One is with Female Pipe Thread (FPT) and the other is Quick Connect Fittings.
In this picture, the filter
on the Left has FPT fittings (The Blue Cap is a plug to keep debris out
of the filter). With this type of filter, you have a fitting that screws
into this filter and the tubing connects to this fitting.
filter on the Right has Quick Connect fittings. With this type, the tubing
is simply "Pushed In" to the filter and is held in place by the Quick Connect
If your inline polishing filter has FPT threaded fittings, the most common size is 1/4".
As you can see in this picture,
1/4" FPT is approximately 1/2" wide if measured with a tape measure.
The tubing on the LEFT is 1/4" tubing. The tubing on the RIGHT is 3/8" tubing. Most times, the tubing is labeled with the size. Just look on the tubing and it will have writing on it telling you the type and size.