BS Cast-in-place Filter Plate · Technical Reference & Specifications

What a cast-in-place filter plate is

A cast-in-place filter plate is a reinforced concrete filter bottom that is formed, poured and cured inside the filter tank itself, instead of being assembled from individual precast concrete plates. The filter nozzle sockets are set out on the formwork to the design grid and cast into the slab during the pour, so the finished filter floor carries a fixed and uniform nozzle layout across the whole tank.

Because the slab is placed as one continuous element, the filter bottom has no joints between separate plates. On filter floors that use air scour, those inter-plate joints, together with the plate-by-plate levelling work, are the details that need the most care; cast-in-place construction removes them and forms the nozzle deck in a single operation.

Structure and construction sequence

The exact sequence is set by the contractor's method statement for the project; the steps below describe how the plate is normally built.

1. Formwork and socket layout. Formwork is erected in the filter tank and the nozzle sockets are positioned and fixed to the design grid spacing, at a common level across the plate.
2. Reinforcement. Reinforcement is placed and tied to suit the plate thickness and the backwash and air-scour design loads.
3. Perimeter detail. The plate is detailed at the tank perimeter and around penetrations, including the waterstop or sealing arrangement between the plate and the tank walls.
4. Concrete pour and consolidation. Concrete is poured and compacted so that it fully surrounds each socket without displacing it; the socket positions and levels are checked before and after the pour.
5. Curing and striking. The slab is cured and the formwork is struck once the concrete has reached the strength required by the project.
6. Nozzle installation. Filter nozzles are fitted into the cast-in sockets and the deck is checked for level; individual nozzles can be removed and replaced later without disturbing the plate.
7. Filter media. The support layer and filter media are placed on the finished plate, matched to the nozzle height and the filtration duty.

Nozzles are supplied to suit the cast-in socket type, in tower or mushroom pattern with long or short handle, in ABS.

Where cast-in-place bottoms are used

Cast-in-place filter plates suit filters where a continuous, rigid nozzle deck and a secure connection to the tank structure are wanted — in particular filters that use combined water and air backwash, and filters whose plan shape or size makes an assembly of precast plates awkward to level and seal.

• Rapid gravity filters and V-type filter bottoms in waterworks
• Biological aerated filters (BAF) and denitrification filters
• Activated carbon contactors and adsorption filters
• Iron and manganese removal filters
• Tertiary and polishing filtration in municipal and industrial plants
• Seawater and desalination pre-treatment filtration
• Filter upgrading and reconstruction, including replacement of failed plate assemblies

Specification data

Configuration is confirmed against the project drawing. Parameters marked on request are quoted for the specific tank, nozzle grid and load case rather than taken from a fixed catalogue.

Parameter	Value
Product type	Cast-in-place (monolithic) concrete filter plate with embedded filter nozzle sockets
Construction method	Formwork, nozzle sockets and reinforcement installed in the filter tank, then concrete poured in place and cured
Plate thickness	On request
Concrete grade	On request
Reinforcement	On request
Nozzle socket type	On request
Nozzle grid / spacing	On request
Tank plan dimensions	On request — cast to your filter tank drawing
Perimeter joint / waterstop	On request
Surface finish & level tolerance	On request
Matching filter nozzles	ABS, tower or mushroom pattern, long and short handle — sized to the cast-in socket
Factory / site work	Cast at site in the filter tank; nozzle sockets and matching nozzles supplied by us
MOQ / price	On request — confirm drawing, quantity & destination

What we need to quote

Send the following and we will come back with the casting arrangement, the matching nozzles and the export packing:

• Filter tank plan drawing, with tank internal dimensions and wall details
• Nozzle type and the required nozzle grid spacing
• Plate thickness, concrete grade and reinforcement requirement, if already specified
• Backwash and air-scour design data used for the structural design
• Quantity, project destination and required delivery date

If those details are not fixed yet, tell us the filter duty and tank size instead — we will work from that.

Notes

Parameters are confirmed per project; items shown as on request are not fixed catalogue values and should not be read as published performance figures. The BS series designation, the final plate thickness, socket type and nozzle grid are confirmed against your project specification before order. Price is on request and is not published on this site.