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4" vs 5" supply hose, which would you put on your truck?
I recently came in contact with a department that was looking to change from 5" LDH to 4" LDH, I Know that I work for a department that made the change in the opposite direction, saying that the one inch differece, was big to the extent of close to double the friction loss when moving big water. I would like to hear any other feed back from you all, so that when I debate with this desk commander, I can present a good case. I think they main objective is the weight and size of the hose when it is charged, which is in my opinion, most of the time when your needing a supply line its because you have a big enough fire that you need water, why not have alot of water.
Replies to This Discussion
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Permalink Reply by Eat The Roof on
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Sorry to get off topic Mark,I just felt a need to address the concerns on why anyone would still be using 3" for supply.
P.S.Go with the 5"
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our 2nd due does back down and reverse lay,still blocks the street when it is charged before trucks arrive no matter how it is laid.
2x3"'s will supply all the water you need almost 100% of the time as well.On really big fires you will be tagging more than 1 hydrant and more than 1 engine will be pumping regardless.
Never said you couldn't pick up 5" with 3 guys, I just find it much less of a hassle to pick-up 3"
If you have 1000' supply we would supply with LDH as well.What i'm saying is that most of our lays are 200' or less so 5" just doesn't give us any advantage AND is immovable once charged.
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Permalink Reply by capcityff on
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The thing you keep missing is that we don't lay dual lines that often. It's VERY rare that we do. Water supply issues are rare here, especially with so many companies responding in a short time. IF 5" is needed, it's there on our water supply companies. Each battalion has one and they dispatch them automatically on the box in areas with less hydrants.
Like 55 Truck said, we aren't just making this up. So far every big city guy has posted that they usually use 3". With as many runs as we go on(between DC, Milwaukee, and Indy) without any problems, I think that it's working fine. If I was on a smaller department 5" would probably be better, but I'm not. 3" works fine for our department even though it might not for yours. No use changing.
Also like mentioned, there's no drying/washing hose after each time it's laid. We drop that hose on the ground several times each day. There plenty of times that we pick it up, get in the wagon and then get sent straight to another box. No need to wash it.
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Permalink Reply by Don Catenacci on
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Gotcha, loud and clear.
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Permalink Reply by Jack/dt on
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capcity
Right...and you probably don't wear seatbelts and dress en route.
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Permalink Reply by Ben Waller on
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Laying dual 3-inch generally blocks more street than does a single 5-inch.
Why lay supply line based on moving it - just lay it right the first time so it doesn't have to be moved.
It also takes less time to pick up a single 5-inch line than the time required to pick up two 3-inch lines of the same length.
That has the advantage of reducing out-of-service times as well as les overall hassle.
And one thing you overlooked - 5-inch ALWAYS has an advantage over 3-inch - more water available if something unanticipated happens and you need a lot of additional water IMMEDIATELY.
Missing something on the size-up, a sudden increase in wind, an unanticipated fuel source inside the structure...
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Gotcha. I am aware of how much water 3 inch will move. My first POC FD used 3 inch supply for years. If we laid duals one was 3 and one was 2 1/2. We switched over to 5 inch and the 3 inch became our apartment line, or for feeding FDC or portable deluge guns.
Your cops and ours I am sure have just a slight difference in work load and types of calls. probably what makes them a little more available to us quicker than your cops.
Dude, I am fully aware of the capabilities of the Milwaukee FD. The fact is you can overwhelm most fires with staffing and rigs. Not many other places can do that without mutual aid.
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One other thing goes in part with something you mentioned earlier. We have great staffing. So in result of that, we don't have as many big fires as other departments. I'm not saying that we are good firemen and others aren't. It's just that with good staffing and large responses, it's much easier to catch the fire in its early stages and make an aggressive attack. I worked for a smaller department before and this rarely happened even though it was full of great firemen. It's just how the setting is.
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We don't lay the supply line based on moving it -the narrow street and parked cars dictates where it is placed not us.-charged 3" inch can be moved off to the side charged 5" CANNOT without great difficulty.
usually only 1 3" is charged unless the other is needed
Picking up and reloading 3" has been faster in my experience than picking up and repacking 5" -If there is a time advantage either way I'd say it would be very nominal and not effect back in service time ,as there are many other things which need to be squared away before you are back in service(saws,tools,personnel,SCBA) other than just hose and besides,it is most likely crew dependant regardless, even within a given dept.(busy crews that run alot of fires are generally faster and more efficient than crews from slower houses)
I didn't overlook the fact that 5 inch can supply more than a single 3" line.what you are overlooking is the fact that 2 3" lines can pretty much supply anything your 1st in engine can handle.and even a single 3" line will give you enough for most any fire situations.
O.K let's look at your scenario of a sudden change of conditions-I am discussing house fires here, not large industrial(that's my point of contention). You pull up on a 2.5 story fire on the first floor. 2 lines are laid (1st line /back-up) attack is begun. A third line is laid to the second floor(extension/S&R) figure ballpark 150GPM per line most likely only 1 line is operating initially but if all three are put into operation I am still only flowing 450GPM-If there is a sudden change in conditions,say the house is filled with gasoline and puppies- it lights up the entire 1st floor,gets into the balloon frame and threatens a nearby exposure -a 4th line is put into operation on the exposure a small line puts us at 600GPM a large line at 700GPM.At some point the incident commander is going to decide wether the initial attack crews are making the fire or need to pull out and go defensive,If they are going defensive A second supply, if not already established will be at this time.You still cannot flow deck guns and water towers yet because crews are still backing out of the structure.So i am still not flowing anywhere near capacity of the 1st supply and engine and am still within the limits of a single ~200 ft 3" supply line albeit one being pumped pretty hard.Charge the second one and it will supply me with everything I can dish out with the initial engine,even pumping to it's capacity.
The thing you are not addressing is that 2 supply lines gives us redundancy in the case of hose failure-doesn't happen often but does happen-single 5" you are SOL.
We haven't used LDH a lot, but I have been, on more than 1 occasion boxed out and unable to get the truck in position because of LDH,and this is with limited LDH usage.This mirrors the experience and observations of other ff's in my 1st due area.
So even given some excessive flow by 5" over 3" I will almost never be able to use that excessive capacity.in addition if I have dropped a 2nd 3" line and it is a reasonably short lay, it will give me NO excessive capacity above the max that our engines can flow.NONE!
So it's more expensive-
Gives me NO real world advantage in flow over short distances.
Is basically immobile once laid
and IMO is a bigger pain to pick-up
Even if I concede the last point(I don't) these are 3 reasons I'll keep laying my 3"
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Don, I think we agree in principal.5" works better for you guys, given your situation.I never said otherwise. I was just trying to clarify why 3" inch happens to work better in our first due.
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Permalink Reply by Scott Taylor on
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At work, we ran with 3" and 5". 3" was used for single fam dwells and 5" for commercial boxes. I always dropped the 5". Playing catch up isnt much fun. Our new engine came in with 4' and a 1250gpm pump so... I remember my limitations and get on the radio if I reach them.
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