What is a filter nozzle

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A filternozzle is a nozzle with a filtration design by which the media isretained and provides a good distribution of water and air.

Use of filter nozzles

Filter nozzles can be installed in sidepipes or on suspended floors. The nozzle has three main components, a filterfor removing media or filling with gravel, a water control orifice, and a tailpipe with an orifice for controlling airflow. The nozzle may rely on the openarea of the filter slot to provide controlled head loss for good distribution,or a separate orifice within the assembly is often preferred. The filter slotsmay be partially clogged with media. This will change the head loss of theslot. If the control orifice is within the nozzle body and the slot has a largeopen area, a partially clogged slot will have less effect on the head lossthrough the nozzle.

Filter nozzle slot sizes vary widelyfrom approximately 0.2 mm to 10 mm, with larger slots most suitable for upflowfilters. Slots of 0.2, 0.3, and 0.35 mm are typically used for direct contactwith the filter media without needing a gravel layer on top of the nozzle. Thisdirect contact facilitates a combination of air flushing and water backwashing.

If slots less than 1.0 mm wide are to beused, care must be taken to avoid the entry of grit with the backwash water. Ifthe filtrate is always used for backwashing, there is usually no problem. Someflooring suppliers market nozzle-free floors, but these rely on filler layersor porous compositions that seem to clog equally or more quickly and are moredifficult to clean.

The filter nozzle tailpipe serves tocontrol the distribution of air. If air is not used, an exhaust tube is notrequired. The tailpipe usually has an upper orifice (starter or vent) and alower orifice or slot (metering orifice/slot). When air is applied to thefloor, suspended or lateral, the air collects under the floor and presses waterdown until the air reaches the metering orifice or slot. The metering orificeis sized accordingly to prevent air from reaching the end of the tailpipe,which would result in poor air flush distribution and localized intenseaeration, which in turn would result in uneven media, possibly carrying mediainto the discharge channel and mixing the filter media layers (if used).

Filter nozzles can be made from variousmaterials, such as plastic and metal, and are supplied with auxiliarycomponents for installation in concrete, sheet metal floors, and lateral pipesystems.

If you would like to customize orpurchase high-quality filter nozzles, please contact nozzle manufacturer CY Spray.

Reprinted from CY Spart – “What is a filter nozzle”