The RO membrane ATD end cap, or anti-telescoping device, supports the ends of a spiral-wound membrane pack and limits axial movement of the membrane leaves when pressure drop develops through the feed channel. WECOME supplies yellow grille-style ABS caps for 4040 and 8040 industrial RO element manufacturing.
CAP-4040G and CAP-8040G are supplied as production components for element assemblers. Final cap geometry, centre-tube interface, brine-seal arrangement and compatibility should be approved against the buyer’s element drawing or physical sample before volume production.
An ATD end cap restrains telescoping and supports the membrane-pack end face while keeping feed-flow passages open. It is not the pressure-vessel end closure and should not be treated as the only sealing component. Element sealing depends on the complete design, including the brine seal, permeate-tube interfaces and pressure-vessel hardware.
Why an ATD Is Fitted to Both Element Ends
Feed-side pressure drop can push wound membrane layers in the direction of flow. A correctly matched ATD spreads the axial load across the element end and helps the rolled structure remain aligned.
4040 and 8040 Grille-Style ATD End Caps
Select by the finished element architecture, not by nominal diameter alone. Centre opening, outside diameter, grille profile, brine-seal seat and mating dimensions must match the approved drawing.
4040 RO Membrane ATD End Cap
Yellow ABS grille cap for compatible 4-inch industrial, commercial, pilot and large residential RO element programmes.
8040 RO Membrane ATD End Cap
Yellow ABS grille cap for compatible 8-inch industrial and municipal RO element manufacturing.
RO Membrane ATD End Cap Specifications
| Part Number | Product Size | Material | Appearance | Qty / Box | Boxes / Pallet | Carton Dimensions | G.W. / Box |
|---|---|---|---|---|---|---|---|
| CAP-4040G | 4040 grille cap | ABS | Yellow ABS, grille style | 200 pcs | 20 | 460 × 460 × 300 mm | 8 kg |
| CAP-8040G | 8040 grille cap | ABS | Yellow ABS, grille style | 60 pcs | 20 | 410 × 410 × 630 mm | 10 kg |
Nominal 4040 and 8040 designations do not define every interface dimension. Confirm the dimensioned drawing, tolerance, ABS grade and required water-contact documentation before ordering.
What the End Cap Must Control
Telescoping resistance
Rigid end support helps limit axial displacement of membrane leaves and feed spacer under operating pressure drop.
End-face load distribution
Consistent ribs and grille geometry distribute contact across the rolled membrane pack without sharp flash or local stress points.
Open concentrate pathway
The grille must support the end face while retaining the intended feed and concentrate flow area.
Repeatable assembly fit
Centre opening, perimeter and mating features must align with the central tube, wrap and element-end architecture.
Sealing boundary: the ATD can support the brine-seal arrangement and the assembled element geometry, but the cap alone does not seal the pressure vessel. Brine seals, O-rings, interconnectors, vessel adapters and correct shimming remain separate design responsibilities.
How to Specify a 4040 or 8040 ATD Cap
Confirm the element architecture
State 4040 or 8040, membrane-leaf count, finished diameter, outer wrap and target application.
Send the interface drawing
Define cap OD, centre opening, overall thickness, insertion features, shoulders, ribs and all tolerances.
Define the sealing arrangement
Show the brine-seal position, groove or seat, permeate tube and any O-ring or adapter interfaces.
Share operating conditions
Provide feed pressure, expected pressure drop, temperature, water chemistry and cleaning or sanitisation agents.
Approve material documentation
Confirm ABS grade, colour, water-contact requirements and the certificates needed for the destination market.
Validate with a production sample
Check fit, membrane-pack contact, feed-flow opening, brine-seal interface and assembled-element performance.
Match the ATD to the Element Format and Operating Duty
Application labels help define the environment, but the approved membrane-element drawing remains the governing document.
8040: high-output industrial and municipal trains
Inspect Geometry Before Assuming Compatibility
An end cap can look correct but still create poor fit, blocked flow area or uneven loading. Incoming inspection should connect the moulded part to the complete element assembly.
Frequently Asked Questions
What does ATD mean in a spiral-wound RO membrane element?
ATD means anti-telescoping device. It supports the end of the wound membrane pack and helps limit axial shifting of membrane leaves caused by pressure drop through the feed channel.
Does an ATD end cap seal the pressure vessel?
No. The ATD is an element component, not the pressure-vessel end closure. Complete system sealing depends on the brine seal, O-rings, permeate interconnectors, vessel adapters and other correctly matched interfaces.
What is the difference between CAP-4040G and CAP-8040G?
CAP-4040G is intended for a compatible 4-inch element design and is packed 200 pieces per carton. CAP-8040G is intended for a compatible 8-inch design and is packed 60 pieces per carton. Exact fit must still be confirmed from the element drawing.
Can a nominal 4040 or 8040 size guarantee compatibility?
No. Nominal format alone does not define centre opening, cap thickness, brine-seal interface, rib profile or tolerances. Submit a dimensioned drawing or approved physical sample.
Can the 4040 ATD cap be used in residential RO systems?
It may suit whole-house or large residential equipment that genuinely uses compatible 4040 elements. It is not intended for standard 1812, 2012 or 3012 point-of-use membrane cartridges.
What should be checked during incoming inspection?
Check critical dimensions, flatness, warpage, moulding completeness, grille openings, ribs, flash, centre-tube fit, brine-seal interface, material documentation and lot traceability.
Do you supply other components for 4040 and 8040 RO elements?
Yes. WECOME supplies central tubes, connectors, brine seals, membrane sheet, feed spacer, permeate carrier, adhesives, fiberglass materials and matching production equipment.
Related Components and Technical Resources
Confirm the ATD from Your Element Drawing
Send the 4040 or 8040 cap drawing, centre-tube interface, brine-seal arrangement, ABS requirements and expected order quantity.