How Does a Smooth Bore Firefighting Nozzle Work?

How Does a Smooth Bore Firefighting Nozzle Work?

This video explores the relationship between solid stream nozzle flow rates and nozzle pressure, as well as what happens when something changes with your flow.

What is a Smooth bore Nozzle?

A smooth bore nozzle is a firefighting nozzle capable of producing a solid, straight stream of water.

The Smooth Bore Nozzle Formula 

If you know a few basic pieces of information, you can calculate either your flow (GPM) or nozzle pressure using this formula:

GPM = (29.7)(d)2 (√NP) 

GPM = Gallons Per Minute

29.7 = a Constant

d = Nozzle Orifice Diameter in Inches

NP = Nozzle Pressure PSI (Pitot Pressure)

Watch the video to see the formula in action!

Does Reducing Flow Also Reduce Pressure? 

Yes, but how the two are related may surprise you! Cutting your smooth bore nozzle flow rate in half reduces the pressure by a lot more, which you can demonstrate with the smooth bore formula. This scenario is explored further in the video.

Continue learning about different firefighting nozzles with us!  

Learn how selectable firefighting nozzles work with this video.

Looking for information on an automatic fire nozzle? Learn how automatic nozzles work here.

Explore how fixed flow nozzles work here!