Just curious what diameter hose your dept uses for primary attack lines. Our dept uses 2" preconnects all around and has for many years. We take it for granted, but I know many neighboring depts that use 1.5" or 1.75", and are often surprised we use what they consider to be a fairly large diameter in 2".
According to one manufacturer's flowchart, for 100' lengths 1.5" hose tops off at around 180GPM @ 75PSI and 1.75" tops off at around 280GPM @ 105PSI, whereas 2" tops off at around 400GPM @ 95PSI. That's pretty significant increase in my opinion. By comparison, a 2.5" line tops off at around 450GPM @ 35PSI. Not much more flow over a 2", albeit at a much lower pressure which is nice. Of course, all these figures are from "perfect world" flowcharts, but the relationship between diameters still applies as the same test was run on the same type hose under the same conditions.
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Thread: Primary attack line diameter?
05-21-2006, 06:20 PM #1
Primary attack line diameter?
05-21-2006, 06:37 PM #2
This one has been discussed at length, but I think your idea to make a poll is intesting. It will be interesting to see how the numbers play out.
And fyi, we use predominantly 1.75 with fogs, but we do also have a 2 1/2 pre-connect on our main engine (with an automatic fog) for bigger fire.
Never argue with an Idiot. They drag you down to their level, and then beat you with experience!
05-21-2006, 06:38 PM #3
It depends on manning, building size and counstruction and other factors. If the fire is in a private dwelling chances are that the 1 3/4" will be pulled. This also allows for the team to move quickly and search as they go. If we are talking a fire in a warehouse at the large plate glass factory in town........yeah we will definatly be pulling a 2 1/2" off the truck.------------------------------------
These opinions are mine and do not reflect the opinions of any organizations I am affiliated with.
05-21-2006, 07:17 PM #4
We use 1 3/4 200' preconnect lines as first in attack lines with a fog combination nozzle and 1 (100') trash line.. How ever each Engine and our Trucks have 1 (2") preconnected @200' that would be used if a fire is defensive mode of the start used as a blitz attack.
05-21-2006, 07:29 PM #5
General rule for us
Fire out 2 windows or less 1 3/4
Fire out more then 2 windows 2 1/2
Commercial 2 1/2
Honestly we pull the 2 1/2 the most. We can move it very well with a 4 man engine crew. We train with it a lot though. When we do end up pulling a 1 3/4 its like having nothing with you.
Last edited by cdemarse; 05-21-2006 at 07:31 PM."Train as if your life depends on it"
Always Remember *343*
05-21-2006, 07:37 PM #6
- Join Date
- Oct 2005
According to one manufacturer's flowchart, for 100' lengths 1.5" hose tops off at around 180GPM @ 75PSI and 1.75" tops off at around 280GPM @ 105PSI, whereas 2" tops off at around 400GPM @ 95PSI. That's pretty significant increase in my opinion. By comparison, a 2.5" line tops off at around 450GPM @ 35PSI.
Well, that must be from a chart that is a great tool for a salesman to obfuscate and confuse people until they give up and buy his product.
Pretty much, that's some nice numbers, and completely useless to making a decision.
1) Who uses 100' long lines?
2) Why are they using different nozzle pressures?
That could work with constant gallonage fog nozzles; If you're using automatic (constant pressure) fog nozzle or a smoothbore those numbers aren't standard. The constant pressure fogs are generally rated at 100psi or 75psi. The Smoothbores at 50psi.
There are several things that are more important than your flow:
1) Your ability to find the fire
2) Your ability to advance a line to the fire
3) Your ability to use the nozzle properly to extinguish the fire
If you don't have 1, 2, and 3...you don't have to worry about what your flow is.
If you've got 1, 2, and 3 covered then you can look at the specifics of your situation and experience to decide what flows make sense; and what hose & nozzle combination will achieve those flows.
05-21-2006, 09:18 PM #7Originally Posted by Dalmatian190
Incidentally, we also have preconnected 2.5" lines that we use for anything more than a residential room or two and contents or commercial buildings. The smallest line we have/use, however, is 2" of normally at least 200' preconnected lengths. That obviously isn't counting 1" forestry/booster which is never used for anything other than the smallest outside trash fires or small brush fires or mop up.
05-21-2006, 10:21 PM #8
- Join Date
- Oct 2002
- The North East
1,75" or 2.5" lines are both primary attack lines in our dept. The choice of what to pull is up to the officer, though at the obvious jobs lines are stretched without a spoken word.
05-22-2006, 09:16 AM #9
We use 1.75 most often, 2.5 next.
and to be honest, your "chart" was really useless, but I answered your question. Is that better?"This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?
05-22-2006, 11:57 AM #10Originally Posted by Bones42
So what if the chart wasn't 100% accurate? Are you one of those people who stands at your pump panel with your IFSTA manual and fire flow chart doing all these algebraic calculations before you can even pull a discharge gate? I doubt it. The numbers I gave were something I found online and were only supposed to illustrate in GENERAL TERMS how you will get a fair amount more water from what seems like an insignificant increase in hose diameter. That's all, I'm not teaching a friggin pump class here.
I was trying to make the point that having more water available initially can definitely help you achieve a faster knockdown, and you will wind up using LESS water in the end as you'll be one step ahead of the fire's ability to spread. This wasn't a thread about hoseline techniques or what needs to be done before worrying about how much GPM you can attain. There are other threads to discuss and argue that.
Last edited by Chauffer6; 05-22-2006 at 12:03 PM.
05-22-2006, 02:09 PM #11
Never said it was inaccurate, in fact, i'm very willing to accept those numbers. Problem with the chart is this, what 1 size does at 35psi compared to another size at 95psi compared to another size at 105psi basically leaves no "common" comparison. If it were simply all at 1 common pressure (or even close) it would be at least useful.
whereas 2" tops off at around 400GPM @ 95PSI. That's pretty significant increase in my opinion. By comparison, a 2.5" line tops off at around 450GPM @ 35PSI. Not much more flow over a 2",
And us guys are sorry if we wish for better/more complete information. There is enough useless crap on these forums for everyone. Maybe some expect/hope for better..."This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?
05-22-2006, 04:19 PM #12
Flow Rate not Line Size
The choice of attack line needs to be based on flow rate and mobility. If you don't exceed the critical rate of flow, you won't control the fire and if you can't quickly get the hoseline in the right place to apply the water the same outcome will result.
As many of you have observed, it is essential to compare apples to apples. One way to do this is using the CQ2 formula (IFSTA Pumping Apparatus Operator Manual or any other good hydraulics text). While not particularly useful on the fireground, this method does allow comparison of the impact of changing hose diameter (all other things being equal).
For example, the friction loss at a flow rate of 150 gpm is:
1-1/2" = 54 psi/100'
1-3/4" = 35 psi/100'
2" = 18 psi/100'
2-1/2" = 5 psi/100'
Friction loss at 300 gpm:
1-1/2" = 96 psi /100'
1-3/4" = 62psi/100'
2" = 32 psi/100'
2-1/2" = 8 psi/100'
Friction loss at 300 gpm:
1-1/2" = 216 psi/100'
1-3/4" = 140 psi/100'
2" = 72 psi/100'
2-1/2" = 18 psi/100'
Note that these numbers can vary with the brand and design of the hose (but this provides a good baseline). When thinking about what would work in a given situation, think about the typical length of line, required nozzle pressure (for whatever nozzle you typically use).
On the issue of mobility; I have done time trials with 1-1/2", 1-3/4", and 2" hose and found that the time to deploy 200' lines for offensive fire attack is not significantly different. However, as hoseline diameter goes up, so does weight and the corresponding workload. Also, effective deployment of larger hoselines is more dependent on good hose handling technique.
Something else to think about. Who says that hoselines have to be the same diameter over their entire length? If you have a long distance, use larger hose closer to the pump to reduce friction loss.
We use 1-3/4" with TFT mid range automatics (most of the time) and 2-1/2" handlines with 1-1/4" solid stream tips or TFT automatics (when flow requirements exceed 200 gpm). But there are a wide range of other options that will also work. The key is water in the right volume and form in the right place at the right time.Ed Hartin, MS, EFO, MIFireE
05-22-2006, 04:35 PM #13
- Join Date
- Dec 2005
- clear lake, texas
depends on the building, and the potential fire load. room and contents in a SFD, 1.75, roll up on an appt fire with more than 1 room involved, or any commercial building with smoke showing, im pulling the 2.5 preconnect. better safe than sorry.
05-22-2006, 10:58 PM #14
- Join Date
- Dec 2002
- Central NJ
We run 1.95" diameter attack lines and 2 1/2" for our big lines.
05-23-2006, 03:30 PM #15
- Join Date
- Apr 2004
- Bossier Parrish, Louisiana
Actually, the most common line pulled here is the booster or 1" forestry line as we have 5x-7x the number of brush and wildland fires than all others combined.
Was assuming structure fires in the poll. We rarely, and I mean rarely pull anything but the 1.75". our members and officers are simply not trained to think about the 2.5" and it usually gets pulled, if pulled, well after the 1 1.75s at a commercial fire. That is something we need to work on, but it's not something confined to our agency as I have seen that mindset quite often in volunteer departments here, as well as where I was from in the northeast.
05-23-2006, 05:14 PM #16
Bones - Sorry I snapped a bit, I should've just left the chart out altogether and asked for what size hose everyone uses. Not that I'm really objecting to a good discussion, but it seemed like the point of the thread was going to quickly get derailed.
In any case, I'm actually very surprised to see 2" hose seems to be so rare. I'm very happy that our dept choose long ago to go with that size, I think the extra water really makes a difference. Some mutual aid companies have commented that it feels quite a bit heavier and bulkier than their 1.5" or 1.75", but obviously we don't know any better as we were either brought up on it or used to it at this point.
05-23-2006, 07:18 PM #17
- Join Date
- Nov 2004
what do the 2" crew guys use as a back up line, 2" or 2.5"?
I've been taught equal or larger for back upand RIT. we don't carry much extra 2".
05-23-2006, 07:56 PM #18Originally Posted by rescue84
05-23-2006, 09:35 PM #19
IF we lost all of our current hose and were to start from scratch, 2" would be considered. Having lived through the switch (little bit at a time) from 1.5" to 1.75", I'd probably shoot myself before starting a 1.75" to 2" switch a little bit at a time. Gets too confusing. It's simply out of our budget to change all the 1.75" lines to 2" with not great enough benefit. And i will agree there is benefit to 2" over 1.75". We've made/kept life simple. 1.75", 2/5", 5". That's it. With our current manpower, handling a 2" over a 1.75" would not be a big deal, heck, the last R&C fire we had I ran with 7 on the first due engine."This thread is being closed as it is off-topic and not related to the fire industry." - Isn't that what the Off Duty forum was for?
05-23-2006, 09:39 PM #20
- Join Date
- Oct 2005
To emphasize Bone's good reply...
So what if the chart wasn't 100% accurate?
It's bad to give out poor information.
Left unchallenged, you have some young buck out there who'd believe their 1.5" line can flow 180gpm, and there's only a 50gpm difference between a 2" and 2.5" line.
Knowing the fire service and how much attention most people pay to reading the responses, that's probably still true even after correction.
I'm perfectly happy with 1.5" as a bread-and-butter line upto and including room and contents fires or several rooms in a residential building if the fire hasn't extended to another floor. Most of our fires are in SFDs or small MFDs (usually 4 or fewer apartments on 3 floors or less). 1.75" is the next option, then 2.5".
I can not think of a situation where an 1.75" line was ever overwhelmed during an interior attack in my department by the fire. I have seen the smaller handlines (1.5" and 1.75") take out far more fire than I expected, including one 3 story building with fire showing on 3 floors that I wrote off on arrival...and our guys left standing using just two small handlines.
I've also seen less fire turn into a building being lost -- sometimes by factors that can be fixed by training and reviewing fundamentals, sometimes by the factor of somedays you're just gonna make a parking lot and there's nothing you can do to change it. None of those was insufficient flow -- it was the inability to get the wet stuff on the red stuff at the right place and time in the right way.
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