More Standpipes: 2.5″ or 1.5″ Line?

In response to my last post regarding standpipe or high-rise racks, Tim Linke from Lincoln, NE had some valid questions about 2.5″ lines instead of 1.5″…  Tim asks:

Now, for a question…and please don’t think that I’m trying to come off like a dick, for I haven’t had the pleasure (or displeasure) of fighting a high rise fire…but why the 1.5” instead of a 2 ½” line?  In our area, we see potential for having restricted flows in standpipe systems, and coupled with the high friction loss of this line, I can see the benefit of having a larger caliber stream.  Again, I’m just wondering and trying to learn.  A lot of the literature out there (and I’ll be the first to say you can’t believe everything that you read) right now highly touts the 2 ½ line using a nozzle with an 1 1/8” smooth bore tip.  What are your thoughts on this?

Tim, Doug Mitchell & I exchanged a few e-mails on the topic…. Here are our thoughts.

Reply to Tim from Nick Martin:


Sorry for the delay.  I have CC’d Doug Mitchell on this.  As a FDNY lieutenant, he is a little more familiar with the 2.5″ high-rise line issue and may have some more comments for you..

The majority of the metro-DC area uses 1.5″ lines in “high-rise” bags.  Everything has pro’s and con’s.  Keep in mind the amount of effort and manpower required to move a charged 2.5″ line – especially if it is flowing water while you’re moving it.  FDNY teams up two 5-person engine companies for ONE attack line.  Most other jurisdictions do not have that kind of manpower available.  Then it becomes an issue of:  low-flow on the fire now (while its smaller) or high-flow on the fire later (when it’s bigger).  There are no disputes that a 2.5″ with 1 1/8″ tip will get you about 320gpm of water.  A 1.5 or 1.75″ will give you between 125-180gpm depending on nozzle selection etc…

I would think if you consistently had the manpower available to get a 2.5″ in-service AS QUICKLY as a 1.5 or 1.75″, then thats great – but few people have that.  Otherwise I’d be a fan of a fast attack with the smaller line backed up with the 2.5″ – under most circumstances… There certainly are exceptions.  

Manpower is my biggest concern with the 2.5″… It’d really suck to have that much water available and not be able to get it on the fire because you don’t have enough people to move it.  There is also the issue of how much did the fire grow /extend while we took the extra time to get the 2.5″ in service.  Was it originally a 1.5″ fire and now its a 2.5″ fire?

Quite honestly in DC, if its below the 5th floor we are very often stretching long pre-connects (350-400′) as long as the building layout permits it.  Most companies are very familiar with their first due buildings.  Its not uncommon to be flowing water on the 5th floor within 2-3 minutes of arrival using a pre-connect.  MUCH faster than any standpipe operation.

Of course everything has to come with a size-up of your buildings, your manpower etc… I’d definitely advocate having the ability to place 2.5″ lines in service in a high-rise, but I’m not sure it’d always be my first line of attack.


Reply to Tim from Doug Mitchell:

Nick summed it up pretty well regarding the 2 1/2. It is manpower driven and without the necessary on scene personnel, the great flows of a 2 1/2 will be greatly inneffective if you can’t get it to the seat of the fire. 2 1/2 is ALL we stretch of standpipes, period. 

You have to practice deploying and operating these lines (vs 1 3/4) to see what works best for you.

Let me know if you need any further info on this topic or anything else for that matter
Stay safe,

For your reading reference, are some resources on standpipes:

7 Responses

  1. What a great website! I just stumbled across this today.

    I would say I agree in full with the comments made by Nick and Doug. I would add further that in Europe we are now exploring the 2″ attack line for standpipe operations. This is nothing new I know and I remembering hauling the stuff around whilst working on detachment with LAFD as far back as 1990.

    We have researched 2″ lines (51mm) extensively in the UK and estimate that firefighters are challenged far less from a physiological standpoint compared to larger lines and yet they are still flowing good amounts with lesser friction factors on high-rise floors.

    The difference between a 1.5 inch and a 2 inch line is a great deal in terms of flow (depending on the standpipe pressure) but 2 inch is far lighter and easier to lay in, needing less firefighters to achieve.

    Thanks for this great website resource.

  2. I have mixed feelings about the only 2 1/2 standpipe packs. However, thats what we run with in Pittsburgh. The nozzle of choice is smooth bore with a 1in tip that breaks to an 1 1/8. Many of our commercial high rises as well as many other North Eastern cities. Were buit pre-code. Meaning no sprinklers… 2 1/2 is a must in that case. When you get into the compartmentlized residential, fire resistive buildings, the 2 1/2 is hard to move around! Well lets be honest is hard to move all the time. Our 2nd Engine is to assist with the advancement. Like everyone has stated manpower is a must. A Quick hit is great in that case! DCFD’s operation concerning the long line deployment up to the 5th is quick and effective!

  3. Paul,

    Thanks for the compliments, great to have people from the UK visiting. Its interesting that you brought up 2″ for standpipes, as you never seem to hear much about that… Its usually either 1.75″ or 2.5″. Could 2″ offer some middle-of-the-road beneifts? Worth looking into…


  4. The reason for 2 1/2 inch hose on standpipes.

    The reason for 2 1/2 inch hose on a standpipe is based on water flow and fiction loss. When the decision to require 2 1/2″ hose on standpipes was made, the primary source of water to the line was from the BUILDINGS STATIC water supply, either on the roof or in holding tanks on upper floors. The water presure for the water flow is derived from the pressure of the water being significantly above the nozzle. If the water is 25 ft above the nozzle ( as it would be on the top floor of a building) the pressure available is approx 50PSI, however 1 3/4 hose has frinction loss of approx 25 psi per length, and 2 1/2 inch hose a friction loss of 5 psi per lenght. (note: I am stating apporximates but they are relatively close) This is simple math. If you use 1 3/4 inch hose the pressure at the nozzle will be very poor, immeidtley after you open the nozzle. It may be great when you first open it becasue the friction loss caused as the water moves through the hose has not set in just yet, But it is coming and very fast. Often ff’s operating a ine under these conditions start to move in and then feel as if they lost water, because to stream becomes so poor. The truth is they really never had it. When they were at the door and about to go in, they only had STATIC water pressuer, not flowing pressure. Look at the Building codes to see where the roof tank must be placed and why, look at the Hydraulics books to find out the impact of water Flow in small diamenter hose lines.

    Once a reliable secondary supply ( one or two pumpers supplying water under pressure is assured, then you could go to 1 3/4 inch hose – but the 1st or primary line should be 2 1/2″. In buildings 5-6 or 7 stories there may be no need to use the standpipe systems. Ground based operations, with hose lines stretched up the building are often just as rapid and more reliable.

  5. Chief Murtagh,

    Thanks for your input & reply. The issue of building water-tanks is certainly an interesting historical point. Here in the metro-Washington area we do not have that issue. I’m not really sure if its because our buildings or not as old, or not as tall – the tallest building in DC is not allowed to exceed the height of the Washington Monument.

    What is interesting, if I read your post correctly, is it seems that the primary or initial reason for FDNY’s use of 2.5″ lines is friction loss, not so much GPM flow. While the GPM flow is certainly a wonderful “extra”… I say this only because many people seem to assume that it was / is all about the GPM.

    That is not to say that the extra GPM is not wanted or needed, I know that certainly a few of FDNY’s recent high-rise fires (particularly the wind-driven ones) have highlighted the need for extra GPM. However one point I was trying to bring up is the manpower needed to put a 2.5″ line in service. Major metro FD’s like ours have the luxury of having many FF’s on scene, fast. I know FDNY uses two 5-man engines to stretch 1 line, if I am correct.

    For FD’s without that staffing luxury, I think the ball is sometimes in the air: what is better, a 1.75″ line NOW, or a 2.5” line in 15 minutes…. Of course I’m not sure the answer to that question is always constant….

    Thanks again & please share more of your thoughts and experiences with us.


  6. Nick,

    At work in Hagerstown we carry 100 ft of 1.5″ single jacket hose with a 50 ft extender pack. The reason we use the 1.5″ is we are running with only two on an engine. Meaning that the oficer has to grat the high rise pack and the irons. Down the road in Riverdale we run 150 ft of 1.75″ single jacket hose with 75 ft more in the officers bag.

    In my years I have run every size hand line you can think of. But way back when I started in the fire department at Brentwood we ran a 150 ft of 2″ light weight hose with a break away nozzle. It was a little heaver then the 1.75″ but one fire fighter could still carry it and advance it when charged.

    With all the new things that have come out over the past 17 years that I have been around I think I would like to try a high rise pack of 150 ft of 2″ single jacket hose in 75 ft lenghts. You are making it lighter because you have taken out couplings. Now put a low flow break away nozzle.

    You have a 150-250 GPM line with a pump pressure of about 115psi pluse 5 per floor. Just some things to think about.

    James E. Johns III
    Riverdale Fire Department Inc.
    Assistant Chief
    Training Officer

  7. James,

    Good points. I think, whatever your setup, the key is (as you mentioned) laying the equipment out so it fits your normal crew compliment. We should be splitting the equipment load amongst the crew. As for 2″, I too would like to experiment with that idea. It seems like we’re always between 1.75 and 2.5 without ever exploring 2″. It seems that may offer a good combination of GPM, maneuverability, and reduced pressure.

    Thanks for stopping by,

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