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Can a 2 1/2" hose be used as a hand line for fire attack?
When I first started in the fire department we had two types of hand lines 1 1/2" and 2 1/2". We were taught that when you attack a fire that you always take your first line in, backed up by a 2nd line at least as big or bigger. We were also taught that if you have light fire conditions you can use small (1 1/2") water, but heavy fire conditions require big (2 1/2") water. I know we now have 1 3/4" hand lines, but I did not know that we no longer use 2 1/2" hand lines.
A couple weeks ago I was out drilling with my engine company and was discussing using 1 3/4" and 2 1/2" hand lines, when to my surprise one of my pump operators who has been around 30+ years and happens to be a retired state fire instructor said "you can not use a 2 1/2" house as an attack line it is to big".
What do you think?
Replies to This Discussion
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Permalink Reply by Don Catenacci on
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MY point is simply this, and it is something that has been repeated for decades, 2 smaller lines flowing together the same as a bigger line will not be as effective because of the volume of the stream. The simple fact that it takes far more heat to turn a 300 gpm smooth bore stream to steam than it does to turn a 150 gpm smooth bore stream to steam should seem obvious.
Currenly don't you figure on 2 engine companies to set up and operate a 2 1/2 inch line for a high rise?
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I am no fan of the low friction loss 1 3/4 inch hose. About 2 years before I retired my career FD bought some Ponn Conquest for our highrise packs (Don't get me going on that). The nozzle purchased was an Akron shut off with a 1 1/8 inch tip, 265 at 50 psi. This was a nightmare to operate. If you tried to do the up, down, all around method of deliverng water by moving your hands back on the line the hose would kink in a Z and in training damn near took off a couple of guys heads. Despite our complaints nothing was done. We did our own testing at my station and found that going to a 1 inch tip flowing 210 gpm, or back to our 200 at 75 combo nozzle, made no difference at all in the kinking factor. Finally we put a 125 gpm at 100 psi nozzle on the hose and the kinking was eliminated. So any benefit of low friction loss was lost because you had to have higher nozzle pressure and thus higher nozzle reaction to keep the hose from kinking. The factor often forgotten when going to smaller hose, 1 3/4 or 2 inch, is that at the same flow and nozzle pressure, the nozzle reaction is the same no matter what size the hose is flowing the water.
This testing was done on 2 occasions with multiple firefighters mostly veterans and the problem recreated itself every time we moved our hands off from the nozzle and attempted to move the stream. And it occured whether the hose was moved slowly or rapidly. I can tell you 100% honestly that the same situation ahs NEVER occured with our REAL 2 inch hose.
The other difficulty using the smaller line is that friction loss is greatly increased and then so is pump pressure. Sometimes, especially in long lines, or high rise ops that creates a problem where there simply isn't enough pump pressure or the hose can't take the needed pressure to overcome that increased friction.
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Permalink Reply by Captain Kevin C. Ross on
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Again I would like to thank all the brothers who replied, when I asked this question I already knew the answer as far as my department and especially my crew is concern, I just wanted to see what everyone thought of this statement by a pump operator / ret. state fire instructor. To me his statement scares me that he would think only a 1 3/4" hose can be used for fire attack. Our SOG is that we use 2 1/2" line when necessary, as I said earlier BIG FIRE - BIG WATER / little fire - little water.
We attack with an attack line (1 3/4" or 2 1/2") and back it up with at least the same size or larger, as required by the fire for search & rescue, containment, extinguishment, and overhaul. When we use a
2 1/2" attack line, as the condition change for the better we do downsize to 1 3/4", as well as we will upsize to 2 1/2" as conditions worsen if we stretch 1 3/4" initially. For my department there is a minimum staffing of 4 firefighters on an engine, and they should be able to stretch a 2 1/2" attack line without any problem,
It is common for my department at a large fires to have to multiple 1 3/4" and multiple 2 1/2" lines deployed.
As for departments who do not have the manpower to stretch a 2 1/2" attack line they should not be entering a structure with a smaller hose line if they can not safely enter and at they very least contain they fire with the line they are stretching. They must wait for other companies to arrive to provide the manpower to stretch the larger attack line, when it is needed.
As someone earlier said I hope this ret, state fire instructor did not poison new firefighters into believing that you can not use a 2 1/2" line as an attack line.
Stay safe
Captain Kevin C. Ross
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Permalink Reply by captnjak on
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Yes, we put two companies on a 2 1/2 line for a high rise.
Your other point seems contradictory. You mention "2 smaller lines flowing together the same as a bigger stream". Then in the same sentence you mention that they "will not be as effective because of the volume of the stream". But the volume is the same. And yes it takes far more heat to turn 300GPM to steam than it does to turn a 150GPM stream into steam. But if there are two 1 3/4 lines then we have 300GPM and 300 GPM flowing into an area should provide the same cooling ability whether it's from one line or two.
Earlier the debate was over penetration ability of the streams. Seems we are back to talking about the volume of the streams.
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Seriously, let me try this once more. If you have 2 - 150 gpm streams you do not have the SINGULAR VOLUME of one 300 gpm stream. The problem you are having understanding what I am saying is while the gpm flow TOTALS the same 300 gpm it is not equivalent because in one case the 300 gpm is coming from one nozzle and in the other it is 150 from each nozzle.
The closest smoothbore flow to 150 is a 7/8" tip that flows 159, and the closest flow to 300 is either a 1 3/16 tip at 50 psi flowing 292, or a 1 1/4 " tip at 40 psi flowing 301. Either way the obvious thing here is the smaler stream has an obviously smaller diameter than the larger stream. Why is that important? Because the singular volume of that greater size stream means as it passes through heat more of the original stream will survive. There is no way that holds true for a smaller stream, even if used in tandem.
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It's not that I don't UNDERSTAND what you're saying. It's that I DISAGREE with what you're saying.
I disagree that 300 GPM from a single nozzle is more effective than 300 GPM from two nozzles.
I disagree that there is some kind of advantage to having the stream remain intact or "survive" as it passes through heat.
Why do we want the stream to "survive"? Water cools fire more efficiently when it breaks down into smaller particles. A solid intact stream passing through heat is not doing it's job. If any given stream is passing through an area that is hot enough to break it down, then that area needs cooling too.
If there is data out there or research that's been done which says I'm wrong I'd love to hear about it.
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Captnjak,
Your very own FDNY standard operating procedures PROVE me right. If not, your 2 engine companies that are required to place a single 2 1/2 in service could EASILY carry 2 - 200 foot 1 3/4 inch lines to an upper floor, hook them to a standpipe and flow 182 gpm from each line for a total of 364 gpm. Your standard 2 1/2 inch nozzle, 1 1/8 flows 265 gpm. By your reasoning you are short changing the guys on the fire floor of 100 gpm possible flow by not using the 2 smaller lines. Hell we used to set up a 150 foot 1 3/4 inch standpipe line with a crew of 2 or 3 on my career FD. Your engines have 4 or 5 firefighters on each, you mean to tell me 8 or 10 guys can't carry and hook up 2 - 200 foot 1 3/4 inch lines?
Why use deluge guns or ladder pipes flowing 1000 gpm? Again by your logic 4 - 2 1/2 inch handlines would do exactly the same work. The issue is penetration through heat and volume of water. The higher volume heavy stream gets to the heart of the fire. That is what puts the fire out. Not being eaten away and turned to steam before it ever gets there due to inadequate flow.
If you believe that smaller drops of water are more effective are you leading the charge to change the FDNY from smoothbores to combinations nozzles?
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By the way, none of my previous post should be construed as an attack on the FDNY or its procedures. I was merely using the examples to show that you do in fact use one bigger line instead of 2 smaller ones.
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Our SOP's do not prove your point in any way. As I mentioned earlier, over-pressurizing standpipe systems is a bad idea. 1 3/4 hose has high friction loss. Using two or more of them would require a high amount of pressure. Standpipe systems can fail. If that happens, we have no water at all on the fire.
You say we are "shortchanging the guys on the fire floor", but this is not true either. SOP calls for a backup line on the fire floor. The backup line is also 2 1/2. So now we can put 500 GPM or more on the fire if necessary. The reality of high rise firefighting is that getting an operating hoseline on the fire is a very difficult task. It takes manpower and time. Our SOP is for two companies to team up on each of these lines. The fire floor could be 20,40 or 60 floors above ground and possibly more. The floor areas are very large (sometimes 10,000-20,000 square feet) and often uncompartmented. Even if one company can do that, it's nice to have immediate relief should it be required prior to controlling fire.
We have no engine companies with five firefighter staffing, with the exception of five specialized units.
This discussion has been centered on handlines used for interior structural firefighting. The large caliber streams you mentioned have to have good penetration ability because the nozzle will not and can not be advanced into the building. I don't see their relevance to this discussion.
Do you have a reason as to why it is so important for the stream to get to the "heart of the fire" intact? I haven't yet seen one in your posts. With modern contents fires there is a large amount of unburned fuel being produced and pushed away from the original seat of the fire. There is high heat produced which is under pressure, thereby also moving away from the original seat of the fire. At any advanced contents fire, the "seat of the fire" could be all around us and ready to light up at any moment. This is why the line should be operated on high heat regardless of location of original seat of fire. I'm not saying open the line on the first wisp of smoke, but the traditional idea of going in under the smoke layer and making the fire room before opening the line could be a dangerous notion. Opening the line in a room or hallway that is adjacent to the fire room will cool that area along with some cooling of fire room. It is in no way a waste of water, energy or time and will lead to final extinguishment as line is advanced deeper into fire.
I'm very happy with smoothbores and not looking to change a thing.
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cap,
I never disagreed with the up, down, all around technique, or cooling the overhead. But the water coming from the nozzle has to overcome the heat or it is simply turned to ineffectual steam that does nothing but make the environment harsher for the firefighters operating there.
The funny part is though if you believe small drops are a better extinguisher than the brute power of the smooth bore muscling its way through the heat and bouncing around to get at the heart of the fire you are making the case for a combination nozzle set on a narrow fog with little droplets floating all over the place.
It is obvious that we will not change each other's minds.
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You say the "water coming from the nozzle has to overcome the heat or it is simply turned to ineffectual steam". If it is turned to steam, it has absorbed heat. It has begun to cool the area. It is doing it's job. It will continue to do it's job as the line is advanced.
Where we disagree is your assertion that the stream has to be able to muscle it's way through the heat to get to the seat of the fire. What's at the seat of the fire? More heat. Why is that heat any different from the initial heat encountered that is not at the seat? If we have a room fully involved with fire blowing out at right angle into hallway, the stream can't muscle through the walls to hit the seat of the fire. So what do we do? Go home? No. We operate line as we advance down hallway in order to make that room.
I like the reach of a solid stream. I do like the penetration of a solid stream. I like being able to operate the line ahead of the nozzle team. I have no interest in fog streams for interior structural firefighting.
You have stated repeatedly that you believe the stream has to have the ability to remain intact to the "heart" of the fire in order to effectively extinguish it. (I have been using the term "seat"; I hope we are talking about the same thing.) I am not asking you to change your position.
I am respectfully asking you to explain your position, as I have done with mine. I don't believe that you have explained from a fire supression standpoint WHY that stream has to penetrat fully intact to the seat of the fire.
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Here is the part of my point that you are missing. As the stream is being moved, up down, and all around, part of it is being eaten up and turned to steam, this may be cooling, or it just may be turning the area untenable from the steam if the volume of water isn't great enough, and part of it is making its way to extinguish the fire. Not all cooling extinguishes the "seat" of the fire.
Of course we would operate the line into the overhead as we moved down the hallway towards the room the fire was blowing out of. We would also try to bounce some water off the wall or door into the room as we advanced for more direct cooling.Honestly, this line by you says we are saying exactly the same thing just in a different way. "I like the reach of a solid stream. I do like the penetration of a solid stream." Penetration occurs because the cohesiveness of the stream and the volume of water is greater than the fires ability to destroy it and turn it all to steam before it penetrates.
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