Tricks Of the Trade: Handlines
The second part of the 500 GPM blitz line deployment is delivering the water in the form of a fire stream directed at the fire problem. The stream should be able to deliver the required flow (500 GPM) with enough velocity to reach the burning material. And yes, this has to be accomplished with minimum manpower, in our case, two firefighters.
The key to being able to handle a 500 GPM stream by two firefighters is having the capability of overcoming the force generated from the fire stream back into the firefighters. The amount of force is dependent on the flow, exit pressure (nozzle pressure), and, if a smooth bore nozzle is being used, the diameter of the tip. The following is a list of various nozzle applications at 500 GPM with the corresponding nozzle reaction based on a mathematical equation for either smooth bore or combination nozzles.
It should be noted that the nozzle reaction number obtained from flow tests using a load cell device could have different and possibly more accurate results than the numbers derived from the formulas. So what does this all mean, numbers aside? Know your nozzles, the capabilities, and how to handle them. If it works for you, then it’s probably good.
1-1/4" SB tip @ 115 NP = 282# NR
1-3/8" SB tip @ 80 NP = 237# NR
1-1/2" SB tip @ 55 NP = 194# NR
Combination @ 80 NP = 226# NR
Combination @ 100 NP = 253# NR