Nozzle geometries are typically either cylindrical or somewhat conical. Our injection molded nozzles utilize v-shaped, vertical slots that prevent fouling. Some believe that the older-style conical nozzles have an angular backwashing benefit; however, cylindrical nozzles are manufactured with robust, reinforcing screen ribs that ensure added longevity.
The size of a nozzle is directly proportional to flowrate. Look at both the service as well as backwash rates to determine the controlling design conditions. Comparing some non-lateral nozzle models with the same screen slot size and stem bore diameter, the flowrate capacity for a Type K3 is higher than Types K2 and C2, which in turn are higher than Types K1 and C1, which have a higher capacity than a Type D.
Nozzle density in the underdrain system factors into the flowrate per nozzle. For example, for the same gpm per square foot backwash rate, designing nozzles on 8” centers each way requires 78% more flow per nozzle than designing nozzles on 6” centers each way. Orthos highly recommends nozzles to be located as close as practicable to ensure effective media cleaning through more points of energy input and to potentially eliminate gravel and other types of problematic packing layers.