NFPA 15 section 8.1.2 states "Minimum operating pressure of any nozzle protecting outdoor hazards shall be 20 PSI (1.4 bar)." Whilst NFPA 15:A8.1.2 states "The minimum operating pressure is required for proper pattern development and to overcome the effects of wind. For nozzles with orifices of 3/8" (9.5mm) or less, a minimum pressure of 30PSI (1.4kPa) is recommended." My question is this: Is the minimum operating pressure of outdoor nozzles 1.4 bar and that will overcome the effects of the wind? How is "wind" defined i.e., is this a coastal high wind or a general daily wind? Is the higher pressure of 30PSI only required for nozzles with orifices of 9.5mm or less i.e., if a nozzle is in a windy location but is 10mm is 1.4 bar OK? Also anyone else notice that 30PSI is not 1.4 kPA but just below 2.1 bar? so which is correct? I have an installation and the nozzles are reaching 1.4bar but when tested on a windy day the spray just blew back. Any ideas?
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