When you are specifying a reverse osmosis or ultrafiltration skid, one of the first decisions is the membrane housing size. The two workhorses are the 4040 (4-inch by 40-inch) and the 8040 (8-inch by 40-inch) housing. Both hold a single element per vessel, but they are aimed at very different flow rates.
A single 8040 element produces roughly four times the permeate of a 4040 element in the same length. If your plant needs high flow, an 8040-based system uses far fewer vessels, less rack space and less piping. A 4040 system is the right call for pilot lines, small RO units, laboratories, boilers and ships where flow is modest and footprint is tight.
Throughput is set by the total membrane area, so you size by element count, not just vessel size. We build single-element housings and multi-element vessels (2 to 6 elements in one shell) for both 4040 and 8040. A multi-element 8040 vessel is the most compact way to reach large flows.
For municipal and general industrial feed water, SS304 is usually enough. Choose SS316L when the feed carries chlorides, seawater, acids, or when the line is food- or pharma-grade - 316L resists pitting corrosion much better. All our sanitary housings are polished for clean welds and easy CIP.
Because we are a direct manufacturer, we also customise nozzle position and size, end-cap style, gauge ports and surface finish to your drawing. See our stainless steel membrane housing or the membrane housing supplier page for full specifications, and pair it with our 4040 RO membrane elements.
Not sure which size fits your duty? Send us your flow rate, feed quality and recovery target and our engineers will confirm the element count and vessel configuration - free of charge.
