the localized water stagnation that might occur with a downward directed port pair table 1 shows examples of four nominal pipe outer diameters od for the main piping of the system table 1 further shows exemplary pipe id the particular id associated with the given nominal od may vary based upon pipe material and performance standard or schedule exemplary pipe materials are pvdf alternative materials include polypropylene pp however metal or other pipes may be used the exemplary orifice diameters of table 1 were selected to provide a generally favorable balance between sufficiently high recirculating flow diverted from the diverter and sufficiently low pressure differential across the diverter pressure loss over a range of main distribution line flows through the diverter a fuller optimization could involve consideration of factors including or influenced by the numbers of diverters used the length of the main distribution line as well as any other factors influencing loss along the main line and the like by way of example with the nominal 50 mm od pipe a target flow through the recirculating flowpath 120 was selected as one foot per second 0 30 m s with a 34 millimeter orifice an exemplary main line flow was set at forty gallons per minute 2 5 liter s or a velocity of 5 4 fps.