Stainless Steel
Drain Cap

A stainless steel drain cap — also called a filter nozzle, water cap or strainer nozzle — is the metal media-retaining element screwed into a filter plate. Its wedge-wire slotted cylinder passes filtered water, backwash water and backwash air while holding the media bed in place, and the all-metal body is chosen where a polymer head would not suit the medium or the duty.

Request a Quote Technical Details

Stainless steelBody material

Wedge wireScreen cylinder

Short · LongHandle options

On requestSlot width

Material

Stainless steel

Screen

Wedge-wire cylinder

Cap form

Dome · Flat

Handle

Short · Long

Price

On request

Why this drain cap

Holds the media,
spreads the flow

A drain cap does two jobs at once: it keeps the media bed out of the underdrain and it distributes service and backwash flow across the plate. Slot geometry and body material decide how well it does both.

Wedge-wire slots, not drilled holes

The screen cylinder is wound from V-profile wire, so the slot is continuous around the cylinder and widens behind the surface. Particles bridge the two contact points instead of wedging into the opening, and for the same slot width the open area is higher than a drilled head — which keeps head loss low in both service and backwash.

All-metal body

Screen, cap, stem, nut and flange are stainless steel, so the cap keeps its shape under the repeated mechanical load of air-and-water backwash and suits media beds and service conditions where a polymer head would not be acceptable. The grade is confirmed against the medium for each order.

Matched to the plate you have

Cap form, stem length, thread, flange and sealing washer are set against the plate type, plate thickness and tapping, so an existing plate does not have to be rebuilt. Each cap is threaded in on its own and a damaged unit can be replaced without disturbing the rest of the plate.

Specifications

Technical parameters

Parameter	Value	Remark
Body material	Stainless steel	Grade confirmed against the medium and duty
Screen	Wedge-wire slotted cylinder	Continuous V-profile slot
Cap form	Dome cap · Flat cap	Other forms on request
Handle options	Short handle · Long handle	Selected against the plate thickness
Mounting	Threaded stem with hex nut, flange and sealing washer	Thread confirmed per plate
Slot width	On request	Set by the media grading to be retained
Head diameter	On request	Linked to the plate layout spacing
Overall length	On request	Set by the plate thickness
Thread size	On request	Matched to the existing tapping
Sealing arrangement	On request	Confirm the sealing detail for the plate
Flow per cap	On request	Confirmed with the flow rate and head loss allowance
Backwash duty	On request	Water and air rates confirmed per project
Service temperature	On request	Confirm the medium and operating temperature
Service life	On request	Depends on the medium and operating conditions
MOQ	On request	Quoted against the quantity per filter cell
Price	On request	No price is published on this page

What we need to quote	Plate type and thickness, tapping thread, media grading, service flow rate, backwash water and air rates, quantity per cell, destination port
Documentation	Dimensioned drawing and material confirmation issued with the offer on request

Applications

Where it fits

Biological aerated filters (BAF)Rapid gravity sand filtersMulti-media and pressure filtersActivated carbon filters and adsorbersIon exchange and demineralisation unitsMedia and resin retention in filter platesService and backwash water distributionCombined air-and-water backwashReplacement caps for existing plates

Product gallery

See the cap up close

Three stainless steel drain caps with wedge-wire cylinders on a white background

Two stainless steel drain caps with threaded stems on a white background

Close-up of the wedge-wire slotted cylinder and domed cap of a drain cap

Drain caps arranged in a pattern on a workshop floor

Stainless steel drain caps in bulk in parts baskets

Long-handle drain caps piled in bulk after machining

Stainless steel drain caps piled in bulk at the factory

Close-up of stacked drain caps showing wedge-wire cylinders and threaded stems

Drain caps in bulk on the workshop floor beside a parts basket

Long-handle nozzle bodies stacked in bulk

Drain caps packed closely with white sealing washers at the flanges

Close-up of drain caps with white sealing washers fitted at the flange joint

Send us your plate and media data

Tell us the plate type and thickness, the tapping thread and the media grading — we'll confirm the cap form, slot width, handle length and quantity for your filter cell.

Request a QuoteNo obligation · response within 24h (working days)

Stainless Steel
Drain Cap