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Nozzle Pressure. Designed Nozzle Pressures. Smooth Bore Nozzle - Handline 50 PSI Smooth Bore Nozzle - Master Stream 80 PSI Combination Nozzle - (all types) 100 PSI. What is the “Best Nozzle Pressure”?. 125 psi?. 75 psi?. Lower?. 100 psi?. 85 psi?. Higher?. 50 psi?.

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designed nozzle pressures
Designed Nozzle Pressures
  • Smooth Bore Nozzle - Handline 50 PSI
  • Smooth Bore Nozzle - Master Stream 80 PSI
  • Combination Nozzle - (all types) 100 PSI
what is the best nozzle pressure
What is the “Best Nozzle Pressure”?

125 psi?

75 psi?


100 psi?

85 psi?


50 psi?

the standard says

The Standard says...

100 psi

NFPA # 1964 - Spray Nozzles

2-1.1 Rated pressure for spray nozzles shall be 100 psig. The nozzle discharge rating shall be expressed as a rated discharge at a rated pressure [e.g., 60 gpm at 100 psig.]

discharge performance
Discharge Performance
  • Basic Spray Nozzles shall discharge:
  • No less than rated flow
  • No more than 10% above rated flow
  • Automatic Nozzles shall maintain inlet pressure between 85 psig and 115 psig.
changes to stream with reduced nozzle pressure
Changes to Stream...(With Reduced Nozzle Pressure)
  • Lower velocity
  • Less reach
  • Less impact force
  • Less heat absorption with fog pattern
  • Less airflow when used for ventilation
  • Tendency for hose kinking causing stream disruption & reduced flow
what does the low pressure nozzle provide
What does theLow Pressure nozzle provide?
  • More water flow at a given pump pressure
  • Increased flow when pressure is unavailable
  • Slightly lower nozzle reaction (10-13%)
  • Heavier, denser straight stream
  • Fog pattern contains larger droplets
how much less reaction does a low pressure nozzle have
How much less reaction does a “low pressure” nozzle have?

Reaction= .0505 x GPM x sq. rt. of nozzle pressure

@ 200 GPM

100 psi nozzle pressure = 101 lbs.

75 psi nozzle pressure = 87.5 lbs.

13% Less Reaction Force

what does the higher pressure provide
What does theHigher Pressure provide?
  • Greater reach
  • Better penetration
  • Denser, more opaque fog pattern
  • More push to the pattern
  • Better heat absorption
  • Hits with more force
  • More “action” when it strikes
single or selectable flow low pressure nozzles
Single or Selectable FlowLow Pressure Nozzles...
  • 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 higher nozzle pressure will produce a greater reaction
  • Fixed flow nozzles produce rapid gains in nozzle reaction when only slight increases of gpm are made, once rated flow is reached
automatic low pressure nozzles
Automatic Low Pressure Nozzles...
  • Similar pressure regulation as 100 psi automatic nozzle, only at a lower pressure
  • Maximum reach with available water
  • Able to adjust to varying water supply conditions
  • Consistent hard-hitting streams
  • Nozzle flow control (with slide valve)
dual pressure automatic nozzles
Dual Pressure Automatic Nozzles...
  • Operator can quickly switch from standard pressure to low pressure
  • Useful when standard pressures cannot be developed or maintained because:
    • Pump transfer valve malfunction
    • Incorrect pump operation
    • High elevation losses
    • Long hose lays
    • Kinked hose line
    • Pressure reducing valves in standpipe systems
dual pressure automatic nozzle
Dual Pressure Automatic Nozzle

Note increased flow at lower nozzle pressure. Pump pressure was not changed.