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Fixed & Selectable Flow Nozzles

Fixed & Selectable Flow Nozzles. Combination (Fog) Nozzle Development. Fixed (Single) Flow Nozzles... . Fixed gallonage nozzle has one hole size Smooth Bore Nozzle Single Flow Combination (Fog) Nozzle One correct nozzle pressure To achieve rated flow To achieve optimum performance

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Fixed & Selectable Flow Nozzles

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  1. Fixed & Selectable Flow Nozzles

  2. Combination (Fog) Nozzle Development

  3. Fixed (Single) Flow Nozzles... • Fixed gallonage nozzle has one hole size • Smooth Bore Nozzle • Single Flow Combination (Fog) Nozzle • One correct nozzle pressure • To achieve rated flow • To achieve optimum performance • Pump pressure must be changed each time nozzle or tip is changed

  4. Selectable Flow Nozzles... • Selectable gallonage nozzle has a few different hole sizes • Manually changed • One correct nozzle pressure • To achieve rated flow • To achieve optimum performance • Pump pressure must be changed each time setting is changed

  5. In relation to flow, a stacked tip smooth bore & a selectable gallonage nozzle are the same... A combination of 3 or 4 fixed hole sizes

  6. Flow of Different Size Orifices

  7. Advantages of Fixed &Selectable Flow Nozzles... • Simple and familiar design • Easily serviced with commonly available parts • Economical to purchase • Whenpumped at correct pressure, will provide rated flow

  8. Limitations of Fixed &Selectable Flow Nozzles... • Changing size always requires a change in pump pressure for optimum performance • Varying water supply affects stream performance • Requires good communication between pump operator and nozzle operator • The need for Standard Operating Guidelines to provide for successful operations • Cannot easily change flow based on current fire conditions -- Limited choices

  9. Is This NozzleReally Flowing 95 GPM? • Determining factors are pump pressure, hose line friction loss, and therefore, nozzle pressure

  10. Limitations of Fixed &Selectable Flow Nozzles... UNDER-pressured Stream • Less reach & penetration • Little power or “punch” to the stream • Fog pattern does not absorb as much heat, & provides less protection 50 psi

  11. Limitations of Fixed &Selectable Flow Nozzles... OVER-pressured Stream • Very difficult to handle • Stream may “break up” • Fog pattern may become “misty” & although dense, easily carried away • Greater nozzle reaction - without needed flow increase 150 psi

  12. Nozzle Pressure - Fixed Flow Nozzles

  13. Nozzle Pressure &Reaction Force... • Reaction force is a function of nozzle pressure and flow • At equal nozzle pressures, a higher flow will produce a greater reaction • At equal flows, a greater nozzle pressure will produce a greater reaction • Fixed flow nozzles produce rapid gains in nozzle reaction when only slight increases of flow are made, once rated flow is reached

  14. Nozzle Reaction Nozzle Pressure 75 psi 67.5 lb/f 100 psi 79.2 lb/f 125 psi 88.5 lb/f 150 psi 97.2 lb/f Comparison of Reaction@ 150 GPM

  15. Nozzle Pressure, Reaction, & Flow Single GPM Nozzle

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