I recently uncovered what I see to be a danger for firefighters in structural interior firefighting. When it comes to interior firefighting, gallons per minute (GPM) is of the upmost importance in extinguishing the fire.
When teaching a live fire class, one of the pre-checks I do is to check the nozzles. During one class I picked up the nozzle and the first thing I observed was the gallon per minute range went from 30 GPM to 150 GPM — this was on a one and one-half inch nozzle. I made sure it was set on 125 GPM. In my morning briefing I had addressed the class in making sure the nozzles were set on 125 GPM. When I started burning and leading crews in, I noticed when the student would change the pattern a lot of times they were also changing the GPMs down to 30 GPM by mistake. This is very dangerous to the crews, because in large fires it was not applying enough water to put the fire out. This occurrence happened throughout the day. In debriefing with my other instructors, they had experienced the same problem.
Two days later I was discussing this issue with another chief of a department and he had the same thing happen to him on a house fire. The firefighter on the nozzle thought the nozzle was stopped up and went to flush then back to 125 GPM and the fire went out.
The next day I was teaching a LP Gas class. As we were setting up the pre-connect lines off the first run engine I noticed the nozzles were set on 30 GPM and the department SOG is to be set at 95 GPM.
Throughout the night I had experienced several times where the nozzle was turned down to 30 GPM by mistake.
There are a lot of formulas out there to find fire flow requirements for structures so let’s look at one. The NFA formula is based on offensive interior operations where less than 50 percent of the building is involved. The formula is: Needed fire flow = [(length x width) Ã· 3] x percent of involvement.
Example: For a 25’x25’ building that’s 50 percent involved, the flow would be 25’x25’ = 625 square feet, divided by 3 =208 x 0.50 = 104 GPM. Do we want to fight with 30 GPM?
My thoughts are: why after all the precautions to prevent accidents in the fire service is there a nozzle for attack lines that goes below 95 GPMs? The days of fighting fire with a booster line are over. My other thought is how many firefighters have we already injured because of this issue? Let’s be safe.