Description
The RO Membrane Housing 4040 SS is a stainless steel pressure vessel that holds one standard 4-inch by 40-inch reverse osmosis or nanofiltration element. It is used in small and medium commercial RO plants, typically from about 250 LPH to 2,000 LPH, where one or more housings are connected in series or parallel on a skid. Stainless steel gives a clean, durable vessel that looks professional and suits food, beverage, laboratory and hospital installations.
Why choose a stainless RO Membrane Housing 4040?
- Robust SS304 or SS316 construction
- Professional finish for visible installations in hotels, cafés and labs
- Easy to open with clamp or bolted end caps
- Suitable for low and medium pressure brackish water RO
- Long service life with minimal maintenance

Construction
The housing is a polished stainless steel tube with end caps sealed by O-rings and held by clamps or bolts. Feed water enters at one end, permeate leaves through the central port, and concentrate exits at the other end. Interconnectors and adaptors seal the membrane permeate tube to the end cap. Housings are pressure tested before dispatch.
Typical specifications
| Element size | 1 x 4040 (4″ x 40″) |
| Material | SS304 or SS316 |
| Design pressure | Typically up to 300 psi (approx. 21 bar) |
| Feed / concentrate ports | 1/2″ or 3/4″ (model dependent) |
| Permeate port | 1/2″ (typical) |
For high-pressure seawater applications, an FRP vessel rated for higher pressure is used instead. Confirm the pressure rating for your design before purchase.
Stainless vs FRP membrane housings
FRP housings are lighter and available in higher pressure ratings, making them standard for larger and seawater plants. Stainless housings are popular on smaller commercial RO plants and where hygiene, appearance or physical durability matter. Both accept the same standard 4040 elements. See membranes in our RO membranes range and complete systems in commercial and industrial RO plants.
Installation and maintenance
Mount the RO Membrane Housing 4040 securely on a frame with clamps, allowing about 1 metre of clearance at one end to load and remove the element. Lubricate O-rings with silicone or glycerine, never petroleum grease. Inspect end-cap seals during membrane changes. Learn more about RO on Wikipedia.
Frequently asked questions
Can it be used for seawater? Only if its rating is high enough. Most stainless 4040 housings are for brackish and tap water.
Do you supply replacement end caps and O-rings? Yes, we can source spares for common housings.
Get a quote for an RO Membrane Housing 4040
Farz Water supplies membrane housings and builds RO plants across Oman. Contact us or call / WhatsApp +968 9455 4533.







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