LOW BACK PRESSURE NOZZLE

HIGH-PRESSURE, LARGE DIAMETER WATER NOZZLES USED FOR FIGHTING FIRES CANNOT BE OPERATED SAFELY OR EFFICIENTLY BY INDIVIDUAL FIREFIGHTERS. THIS PROPOSAL DESCRIBES AN INNOVATIVE NOZZLE DESIGN THAT IS EXPECTED TO LOWER THE NOZZLE REACTION FORCES BY 20-30% WITH AN ATTENDANT REDUCTION IN THROW RANGE OF LESS THAN 5%. A LABORATORY TEST PROGRAM TO VERIFY CONCEPT FEASIBILITY WILL BE FOLLOWED BY PROTOTYPE CONSTRUCTION AND FIELD TESTING. THE NEW DESIGN CALLS FOR THE INSERTION OF A FLOW MODIFIER IN THE FLOW FIELD WITHIN THE NOZZLE BODY. THE FORCES GENERATED BY THE FLOW MODIFIER WILL OPPOSE THE NOZZLE REACTION FORCES AND RESULT IN A NET REDUCTION OF THE AXIAL FORCE AT THE NOZZLE GRIP, WITH A CORRESPONDING, BUT RELATIVELY MUCH SMALLER, PENALTY IN NOZZLE EXIT PRESSURE DROP AND THROW RANGE. IN PHASE II, THE FLOW MODIFIER WILL BE OPTIMIZED TO PROVIDE MAXIMUM REDUCTION OF THE NOZZLE REACTION FORCE AND A MINUMUM LOSS IN NOZZLE FIREFIGHTING PERFORMANCE.