How a filter plate nozzle works, its structure and features, its parameters, and how it is installed and applied in gravity and pressure filters.
← Back to ABS Filter NozzleA filter nozzle — also called a strainer nozzle, filter head or water cap — is the distribution element fixed into the filter plate at the bottom of a filter cell. Each nozzle is one flow path between the plenum below the plate and the media bed above it. There is one nozzle per tapping, and a plate carries as many as its layout requires.
During service, water passes down through the bed and enters each nozzle through the slots in its head, then leaves through the plenum to the underdrain. Solids are held in the media; the slots are sized so that the media itself cannot pass through and be lost to the clear water side. During backwash the flow reverses: water — and, in a combined air-and-water backwash system, air as well — is pushed up through the same nozzles and spread across the plate area, so the whole bed is lifted and cleaned rather than only the part that happens to be above the open tappings.
Two properties decide whether a filter cell behaves as designed. The first is the slot opening, which has to retain the media while passing the flow at an acceptable head loss. The second is even distribution across the plate, which follows from the number and spacing of the nozzles and from the pressure loss across the plate assembly. A nozzle line that offers several body styles and a range of slot openings is what makes it possible to satisfy both on a specific cell, including a cell whose plate already exists and whose tapping thread is fixed.
The body is moulded in ABS as one piece. It consists of a slotted head that forms the flow entry and, on most styles, the distribution surface; a stem that carries the flow through the plate; and a threaded section that fixes the nozzle into the plate. Long-handle and short-handle versions differ in stem length, double-head versions present a distribution surface at both ends, and adjustable versions let the working height be set on site. Sealing against the plate uses the gasket arrangement agreed for the order, because plate finish and tapping detail differ between cast-in-place and finished plates.
The slot width is set against the fine end of the media grading so that the bed cannot pass through into the underdrain. The total open area of the nozzle then has to pass the service flow and the backwash flow within the head loss allowance of the backwash pump and blower. Because both figures depend on the media and on the duty rather than on the nozzle alone, the slot width is confirmed with the quotation. The number and spacing of nozzles across the plate are set at the same time, since it is the plate layout — not the individual nozzle — that fixes how evenly water and air are distributed.
| Parameter | Value | Remark |
|---|---|---|
| Body material | ABS | Grade confirmed for the duty |
| Head styles | Tower · Mushroom | Other styles on request |
| Stem options | Long handle · Short handle · Double-head · Adjustable | Selected against the plate type |
| Mounting | Threaded into the filter plate, or set in a cast-in-place plate | Thread confirmed per plate |
| Slot width | On request | Set by the media grading to be retained |
| Number of slots | On request | Linked to the open area required |
| 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 |
| Gasket arrangement | On request | Confirm the sealing detail for the plate |
| Flow per nozzle | 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 |
| Item | Detail required |
|---|---|
| Filter type | Gravity, pressure, biological aerated filter, activated carbon or ion exchange |
| Plate | Plate type and thickness, and whether it is cast in place or already finished |
| Tapping | Thread size and tapping detail, or a sample nozzle to match |
| Media | Media type and grading, so the slot width can be set to retain it |
| Duty | Service flow rate, backwash water rate and backwash air rate |
| Quantity | Number of nozzles per cell, number of cells, and the quantity of spare units |
| Commercial | Destination port and the transport mode |
Price is quoted on request for every configuration; no price is published on this page.
Nozzles are fixed to the plate in one of two ways. In a cast-in-place plate the nozzles are positioned and levelled on the formwork and the concrete is poured around the stems, so the tappings are formed by the nozzles themselves; the row is checked for level before the pour and the head openings are protected while the concrete sets. In a finished plate each nozzle is screwed into its tapping and seated against its gasket. In both cases the heads are brought to one common level, because it is the level of the nozzle heads that sets the flatness of the support under the media bed.
A nozzle does not set the performance of a filter on its own. Plate layout, media grading and backwash duty together decide how evenly a bed is cleaned and how long a run lasts. Send those three and the nozzle selection follows from them.
This reference is compiled from the product record held for this line and from general practice for filter plate distribution in gravity and pressure filters. The confirmed points on this line are the body material (ABS) and the styles offered: tower, mushroom, long handle, short handle, double head and adjustable. Slot width, number of slots, head diameter, overall length, thread size, gasket arrangement, flow per nozzle, backwash duty, service temperature and service life all follow the plate, the media and the duty, so they are confirmed in writing with the quotation rather than fixed on this page.
Images 11 and 12 in the product gallery show nozzles set in a plate before the concrete is poured and a finished nozzle array inside a filter cell.
Where a figure is not confirmed for your duty it is marked On request rather than estimated. Please send your plate data, media grading and flow rates and we will return the nozzle selection, quantity and price with the offer.