Filter Nozzles Material Types and Screen Slot Width

How do you choose which filter nozzles? As the leader in the nozzle-based filter systems and products, Orthos has by far more injection molding capabilities and over a million nozzle design combinations in order to provide the correct solution for your application.  R&D performed in our Orthos Research Center evolves new and improved nozzle products, while others still plug-and-chug mid-20th century legacy products in a one-size fits all manner.

How do we know how to select the correct nozzle product for your application?



Old Nozzles

Material Selection

Orthos manufacturers nozzle products of polypropylene, glass-reinforced polypropylene, PVDF, HDPE, stainless steel, Hastelloy, and combinations of materials such as a stainless-steel screen section with polypropylene stem. 

Polypropylene is appropriate for most water treatment applications. However, for example, if water temperatures exceed 140°F (or 60°C) or if specific chemical resistance is necessary, other materials of construction will be selected.  Orthos will recommend the most appropriate choice to get the job done. 

Filter Nozzles Screen Slot Widths

Orthos Nozzles Slot Sizes

Orthos has numerous screen slot widths that vary from 0.1 mm (or 4/1000 inch) for very small ion exchange resin up to 5.0 mm (or 3/16 inch) for underdrains with a deep gravel packing layer.  Most filtration applications tend to result in screen slot widths between 0.2 mm and 0.5 mm. Orthos polypropylene nozzle cages are color-coded for ease of identification of the slot width. 

This dimension is typically chosen to be between 50 to 70% of the effective size of the smallest media in order to retain the granules as well as to not foul with fines or biology.  For example, the effective size of typical sand filter media is 0.5 mm; thus, a 0.3 mm-slotted screen should be chosen.  A GAC adsorber may have 1.2 mm effective size media; thus, a 0.8 mm-slotted screen would be appropriate.  


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Remember Orthos’ HUGE life cycle cost benefits– At the end of the filter’s life cycle (~25 years), in contrast to a complete plastic block or folded sheet metal underdrain overhaul, nozzles are simply replaced potentially saving $Millions.

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