By: Battalion Chief Shannon Stone
City of Fort Walton Beach Fire Dept. Fla.
Now that I have your attention, take a moment to read this and provide feedback.
Couple of disclaimers; I’m not a writer so please be kind and I’m not advocating the use of 1 ¾ for commercial fires, but rather reaching out to those who are knowledgeable in this area and asking for feedback.
Recently during flow testing apparatus in my department, an engine company approached me and asked me a question. “What do you think about flowing and operating a 1 ¾ line flowing 260 GPM in place of 2 ½ line flowing 260 GPM?” You can imagine my response….”No way, we don’t use 1 ¾ for high flow GPM and we certainly wouldn’t use it to replace a 2 ½ line on a commercial job.” As you can imagine this started a debate which led to much testing and this article for County Fire Tactics. I will make this as brief as possible.
All flows were flow tested with a flow meter at the intake, nozzle reactions calculated multiple times, and tested advancing lines in full PPE simulating fatigue factors (not live fire). An “apples for apples” comparison was done with two identical tests. Both evolutions were performed with a four man company, the same firefighters in the same positions every evolution. They advanced the hose lines into a drill tower room 1, flowing to the left, shut down moved to the right and flowed, advance to the next room and flowed, advanced to the 2nd floor and flowed, advanced to the 3rd floor and flowed. Each time the nozzle was opened it was operated at full capacity for 30-60 seconds. Here are the details:
Evolution #1 – 2 ½ inch Ponn Conquest hose, 200 ft, solid bore nozzle with 1 1/8 tip
- Engine pressure of 80 PSI equaling 265 GPM
- As everyone knows, 2 ½ hose advancement is labor intensive and even with four well trained firefighters, the fatigue factor was still a concern
- Firefighters had to work extra hard to manage the kinks in the line. They were never successful in removing all the kinks and this was performed in a drill tower where the obstacles are far less than an actual building.
- Proper techniques were used by all especially by the nozzle man and back up firefighter
- General assessment of the evolution is that it was very tiring and all firefighters were winded, but of course they said what all firefighters say “But we got it!”
Kink management was difficult at best with the 2 ½ advancement. The hose team was never successful in managing all the kinks in the line. Keep in mind there were numerous pivot points for this advancement.
Evolutions #2 – 1 ¾ inch Ponn Conquest hose, 200 ft, solid bore nozzle with 1 1/8 tip
- Engine pressure of 140 PSI equaling 260 GPM
- Half the weight allowed the firefighters to move the line very easily, much quicker, and more efficient than the 2 ½.
- There was only 1 kink during the entire evolution which was easily corrected by a firefighter.
- Proper techniques were used by all especially the nozzle man and back up firefighter. This is a 1 ¾ line but absolutely has to be operated and staffed like a 2 ½ line when flowing 260 GPM.
- General assessment of the evolution is it was much easier to advance and the firefighters said they felt way less fatigued. They described it as no different than advancing any other 1 ¾ attack line. The nozzle man also stated that due to the smaller diameter of the 1 ¾ hose, he felt it was easier to hold and control the nozzle position.
Bleeding the line checking the stream preparing to advance the 1 ¾.
Although hard to tell by looking at pictures but the kink factor was decreased significantly. Notice the nice stiff bends in the hose in comparison to the pictures of the 2 ½ hose.
Wrapping the wall, stairwell, and rooms are essential with minimal staffed fire departments. The 1 ¾ worked very well due to the high pump pressure. It never kinked when utilizing these advancement methods. However, 2 ½ would kink immediately rendering this technique less effective resulting in numerous kinks.
Here are additional facts:
- Nozzle reaction for both the 1 ¾ and 2 ½ are virtually identical since the GPM and diameter of the nozzle are the same.
- Kink flow testing revealed that on average a kink in the 2 ½ hose would result in the flow decreasing from 265 GPM to 240 GPM.
- Kink flow testing revealed that on average a kink in the 1 ¾ hose would result in the flow decreasing from 260 GPM to 210 GPM. The significant decrease is obviously due to the amount of water flowing through a smaller diameter hose.
- 2 ½ hose was guaranteed to kink, 4 firefighters could not manage all the kinks resulting in a decrease average flow of GPM.
- 1 ¾ hose was extremely difficult to kink due to the high pump pressure. Only one kink that was corrected easily and quickly. The average GPM was around 250-260.
- Low friction loss hose was used (Ponn Conquest). Anyone who is a student of the fire service understands the actual diameter of this hose is slightly larger that standard hose (or slightly larger than what the manufactures actually advertises it as); however, manageability of the low friction loss hose vs the standard hose is identical.
- High pump pressure had no negative bearing on advancement or operation of hose
- The nozzle man has the same range of motion with the 1 ¾ line as the 2 ½ line
- Reach, penetration of the fire stream of each was identical
Advantages of the 1 ¾ option
- Literally ½ weight in comparison to 2 ½
- Nozzle controllability was the same if not better with the 1 ¾
- Line advances easier, faster, and more efficient
- Fatigue factor was much less that 2 ½
- Average GPM was greater than the 2 ½ (kink factor)
Disadvantages and limitations to the 1 ¾ high flow set up
- It is likely that anything over 200 ft of 1 ¾ set up will not work due to high friction loss factors.
- This should not be considered in high rise fires due to high friction loss factors. This would include most if not all standpipe operations.
- If the 1 ¾ nozzle is operated too far out in front of the nozzle man, a serious “whipping or snapping” action of nozzle can occur. This is easily controlled by proper nozzle control and operation.
Summary
A quick special thanks to my guys that insisted I take a look at this. Fort Walton Beach Fire Department Engine Company 7– Acting Captain Justin Westmoreland, Engineer Mark Birchett, and Firefighter Brandon Waterhouse.
The testing we performed was much more comprehensive than what this article shows, but in an effort to make it brief and a quick read I stuck the meat and potatoes of the issue. In no way am I implying that we in the fire service move away from use of 2 ½ hose for large fire or commercial fire attack. However, the numbers and facts speak volumes that I believe are worthy of evaluating. If you think about it, this is no different from the evolution of 1 inch hose, to 1 ½ hose, to 1 ¾ hose, to low friction loss hose which now allows us to flow larger volumes of water under manageable conditions. I do buy into the concept of limiting your nozzle reaction and insuring you have a manageable line so the nozzle is ALWAYS operated properly during significant fire conditions-nozzle all the way open. This is why this 1 ¾ set up absolutely has to be operated as if it is a 2 ½ line insuring adequate staffing to insure correct deployment and operation.
So I beg the question….what are we missing here? What’s your thoughts and/or experiences with high flow, smaller diameter hose? Should this be a viable option for large fire attack?