Outside-flow screens — a cylindrical screen element sits parallel to the bulk flow and water is drawn from outside to inside at very low velocity. The passive, fish-friendly family preferred for SWRO.
Intake Screening for Water & Desalination Plants
In an outside-flow screen the screening surface is parallel to the bulk flow; water is drawn radially from the outside of a cylindrical element to the inside through fine slots at a very low approach velocity. With no moving parts and a large surface area, outside-flow passive screens dramatically reduce fish impingement and larval entrainment — the default for environmentally-permitted seawater desalination intakes.
Cylindrical element parallel to the flow
Cylindrical/half-pipe wedge-wire, ≤0.15 m/s, self-cleaning by ambient current — the SWRO gold standard.
Passive screen on a submerged pipe end, flow entering from all sides.
Multiple cylinders clustered for high-capacity intakes.
Rotating drum with outside-to-inside flow for some coastal intakes.
Pulsed air keeps slots clear under sediment and biofilm.
Copper-nickel and coatings resist marine biofouling.
| Type | Description | Desalination application |
|---|---|---|
| Passive wedge-wire (Johnson) | Cylindrical wedge-wire, ≤0.15 m/s, outside-to-inside | Gold standard for SWRO; minimises entrainment/impingement; slots 1–10 mm |
| T-screen / Tee-screen | Passive screen on a submerged pipe end, flow from all sides | Where intake pipes terminate in open water |
| Drum (outside-flow variant) | Water flows outside-to-inside of a rotating drum | Some coastal intakes; less common than through-flow drums |
| Canister / pod screens | Clustered cylindrical passive screens in a pod | High-capacity intakes where single screens are insufficient |
Continue across the screening knowledge base
Low-velocity, no moving parts — 316(b) benchmark.
Read MorePassive wedge-wire screens on a submerged pipe end.
Read MoreClustered passive cylinders for high capacity.
Read MoreRotating drum, outside-to-inside flow.
Read MoreThe velocity / entrainment / impingement driver.
Read MoreThrough-flow screens set across the flow — traveling, band, drum, bar.
Read MoreThe screening hub for the seawater intake series.
Read MoreOur engineers select, size and material-match intake screening — outside-flow screens and the full train — for your debris load, fish-protection duty and downstream desalination process.
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