# Thread: 5" vs. 3" supply hose

1. ## 5" vs. 3" supply hose

Alright so I said I would never do this, but perhaps never was too strong of a word...

I posted this down in the Engineer's forum, but I'm not sure it gets the visibility that I need to get a quick answer.

We are having a debate on adding 5" supply hose(no cost we already own it as extra) to one of our engines that is currently all 3". Seems that one of my members thinks that it is a waste because there is nothing you can do with 5" that you can't do with dual 3" lines. Problem being some people take what he says as the final word without ever looking into it further. In my dealings with him he is open to comments, correction, etc as long as you have facts to back it up.

I am by no means a water flow calculation guy so I need you guys to crunch some numbers for me and justify either side of the argument, but I need you to elaborate how you came to your results.

Also keep in mind that this is simply shifting the hosebed divider over and adding 500' and keeping the 3 inch so there are options, since no hydrant in our town is further than 500 feet apart and we have a second due engine with 1200' coming in.

Help a guy out will ya!?!?

2. We use 5" on my department. I personally feel that it works much better than 2 other hoses, no matter what size. 3", or around here, 2- 2 1/2". Most of my department agrees also. One big benefit......less hose. If you are going 500' then there is only 500' of hose. If you are using 2 lines then obviously it doubles. (1,000 ft.) There are some draw backs though. It is very heavy. You definately have to drop the line at the hydrant, then drop the hose towards the scene. Other advantages though: Less fittings, no valves or gated wyes.
I guess overall, even without numbers of flow rates and all, there are ther reasons why it is better.
I would have to guess that you could flow more water though because there would be less surface area in the hose = less friction loss and flow rate.

Just tell him it works better.....and that you are always right.

Basically 5" works better as long as you're not weight or space constrained.

4. Man voyager, does that ****** me off. I searched a couple of different keyword combos and came up with nothing really relevant.. thanks for the link it is rather beneficial!

5. Originally Posted by FFTrainer
I searched a couple of different keyword combos and came up with nothing really relevant.

6. It all depends on what type of construction you have. In my area we have mostly houses, row-homes, and 3 to 5 story apt buildings. We have Hydrents on evry corner. Layouts between 250' to 600'. We are an agressive fire dept. so we go inside( Not to say your not). And we on the JOB in minutes. We use 3" hose and we do not have a problem with it. Most fires should go out with tank water but 3" supply should give enough water if needed. We don't lay duel supply lines often unless a large buliding or several house's ore off. On the first Box we have 5 Wagons on the JOB that 2500 Gallons of water that should take care of most fires. I have never had a problem yet with water supply issues. But this is the city not the county. it just depends on where you are at and your areas water supply ability.

7. One argument that I hear is that 3" can be moved when charged and 5 can not. My question to you is when do you move the supply line once it is charged?
Dual 3" will not give you the same flow over distance as a single 5". The other big difference is the clean up. Modern 5" just goes back on while 3" gets rolled, cleaned and then rebedded.
Sure you can get 3" made from the same material as 5", but 3" is more likely to be used in a building and we found out that that style hose on a tile floor is very difficult to move.
At a drill in an old grocery store we tried using TPX rubber covered hose. When it got wet it would not slide on a linoleum floor that you find in commercial buildings.
I would go with 5". You also could get away with some on the front bumper, much like Chicago does. A very nice set up.

8. 5" hose is your friend, I think everybody should have some.

9. 5" is your friend...sometimes like a drunk buddy you have to pickup and haul home after the party is over

Anyway, without more context the "there is nothing you can do with 5" that you can't do with dual 3" lines. " doesn't make much sense.

At best, dual 3" = 1 4" line. 5" will outperform 3", period.

If "nothing you can do" is because of other factors, like having decent pressure, moderate flow (like, oh, 1000gpm per hydrant, 60psi residual) so dual 3" for 500' will get you just as much water as a single 5" because the limitation is the flow of the hydrant. THAT is unusual.

5" wins if you have lay longer; if you have higher flows; if you have lower residual pressures.

10. %' will definatly flow a lot more water. There is no doubt about that. However do do need to thuink about several things...

Do you have the structures that will require a heavy initial water supply or are you primarily making initial attacks with 1-2 handlines?

Do you have the hydrant system to supply 5" effectivly?

Do you make primarily shorter where the 3" works well or longer lays where the 5" shines?

Do you usually have a pump to put on the hydrant with 3" or are yopu flowing water most of the time without a pump because of staffing?

Do you have the budget needed for 5" fittings, reducers and intake vlaves that will be needed?

Do you have access to LDH on 2nd alarms for those large fires? (See the first question ... )

11. The biggest misconception about 5 inch hose is you need to flow tons of water with it. Of course it CAN do that, but it also makes up for poor hydrants by allowing that water to move longer distances under less friction loss. We have a low pressure water system and 5 inch hose allows us to forward lay from the hydrant and get all the water without having to pump the line.

Honestly, unless you ALWAYS reverse lay, or ALWAYS pump the line with the second due there is no comparison between 3 and 5 inch hose. 5 inch will always win.

Fyredup

If your max flow is less than around 750gpm, and short (less than a couple hundred feet) stretches, a single 3" may do it for you. After that it's multiple lines.

Single 3" at 750gpm = 45psi FL/100'

5" at 750gpm - 2psi FL/100'

3" at 1,000gpm = 80psi FL/100', obviously you'll need multiple stretches of 3" to keep the water flowing. But 2-3" lines will deliver 1,000gpm abut 700' at 150psi PDP. 3-3" will deliver it 1,500'

200psi PDP:
- 2-3" lines deliver 1,000gpm 900'.
- 3-3" lines deliver 1,000gpm 2,000'

250psi PDP:
- 2-3' lines deliver 1,000gpm 1,100'
- 3-3" lines deliver 1,000gpm 2,500'

On the other hand...

5" will flow 1,000gpm for more than 3,000' at 150psi PDP.

Get Paul Shapiro's Layin' the Big Lines from www.fireflowtechnology.com for lot's more information.

Volume wise, 5" flows 2.8 times more water with less FL and PDP than 3".

13. Originally Posted by LaFireEducator
%' will definatly flow a lot more water. There is no doubt about that. However do do need to thuink about several things...

Do you have the structures that will require a heavy initial water supply or are you primarily making initial attacks with 1-2 handlines?

Do you have the hydrant system to supply 5" effectivly?

Do you make primarily shorter where the 3" works well or longer lays where the 5" shines?

Do you usually have a pump to put on the hydrant with 3" or are yopu flowing water most of the time without a pump because of staffing?

Do you have the budget needed for 5" fittings, reducers and intake vlaves that will be needed?

Do you have access to LDH on 2nd alarms for those large fires? (See the first question ... )

As for buildings... yes we have a community of 750k to 1Mill homes like 4-5000 sq feet as well as a large agricultural community on the other side of town with barns, and commercial growing businesses.

We have the fittings already since, to answer your question RE: mutual aid companies we are surrounded by 5" capable companies and our second due engine is nothing but 5". We are simply looking to add 5 inch to our first due engine for better water movement. Yes some of our lays are short, but some of our hydrants are iffy and we are looking at a way to move water with less resistance.

As for the pump at the hydrant, that is a time of day/manpower determined answer on any given call, so to answer safely.... no not ALWAYS so we think 5" would be better for when you don't have that engine on the hydrant.

Thanks for the replies so far.

14. Let's turn the question around...is there any justification to go from 5" to 3".

15. Originally Posted by FyredUp
The biggest misconception about 5 inch hose is you need to flow tons of water with it. Of course it CAN do that, but it also makes up for poor hydrants by allowing that water to move longer distances under less friction loss. We have a low pressure water system and 5 inch hose allows us to forward lay from the hydrant and get all the water without having to pump the line.

Honestly, unless you ALWAYS reverse lay, or ALWAYS pump the line with the second due there is no comparison between 3 and 5 inch hose. 5 inch will always win.

Fyredup

These are my thoughts exactly. Our 2nd due pumper lays the line but directly connects into the 1st pumper. This will handle most of our fires. The second pumper can leave or reposition quickly if necessary.

16. Gotta love 5" supply lines. I only hate it when.....

1. No hose bed covers=lots of hose on the interstate
2. When it freezes!

We carry 1000ft on each engine and 600ft on the ladder. We do use it and it just takes practice to gain confidence with 5" LDH.

17. Add/Win.. Nice set up, only its 4 " not 5 on that rig.

18. Originally Posted by Bones42
Let's turn the question around...is there any justification to go from 5" to 3".

When we went to 4" a few years ago, some of what we call the "redbook dinosaurs" (those who took the Civil service entrance exam based on the guidebook that was issued up unitl the mid 1970's) where bitching about "the change"... the main gripes were:

4 inch hose is too heavy.
The lengths are way too long.

Of course, once they were shown that....

a: you didn't need to lay dual lines to get the full capacity out of the hydrant.
b. you didn't need to use any adapters for reverse lays
c. you didn't have to reload two sections of hose bed and keep track of how much went where.

and of course...

d: you didn't need to wash, hang and dry 4" hose!

They were still bitching...

"Why didn't we go to LDH years ago!"

19. Sounds like you would be wise to go to LDH, especially given some of your "iffy" hydrants and potential lack of a pumping engine at some times. Having the adapters is a big plus as it will substancially cut your purchase costs.

20. ## 3 inch

Well ive never used 4 inch, here we have 3 and 5 to lay from the plug. Ive only seen us use 5 inch on large fires. The basic house fire, a single 3 inch line is all you need. I know that alot of fire dept's are going to 5 inch only. But really its not needed around my area. We have a great Fire Dept. that knock's down most fire's with 500 gal's. Most time we dont lay a line. Just put a truck at the plug. Plus are water system is great. If you like the larger hose, our if your just using it for your ISO point's, it's all good. Larger is not alwas better.

Station 1 & 5 Engine's (1200ft 3 inch) (800ft 5 inch)
Ladder's 2133 & 2134 (800ft 3 inch) (2000ft 5 inch)
Station's 2,3,4,6 (1300ft 3 inch)
Station 7 (2000ft 3 inch)
Station 8 Airport (800ft 3inch) (1000ft 5 inch)

21. Originally Posted by LaFireEducator
Sounds like you would be wise to go to LDH, especially given some of your "iffy" hydrants and potential lack of a pumping engine at some times. Having the adapters is a big plus as it will substancially cut your purchase costs.
LAFire.. if you were answering my post

We have an excellent hydrant system.

99% of the city has hydrants ( the 1% of the city that doesn't have hydrants are two private roads, one is along a lake, the other serves 1 old homestea dand has a pond in which we can draft from) , and the average hydrant pressure is 90 to 100 PSI right off the hydrant with the exception of one area, where the average hydrant pressure is 20 to 40 PSI.

22. ## 5"

We went to 5" a few years ago. Still have a choice and that is up to the first due eng. operator. If its a long run, he most definitley will lay dual 3" lines cause we only have 600' of 5". If its close enough for the 5" I prefer to hook directly to hydrant. That frees up the eng. We have an excellent hydrant system. very few places farther than 500' run to hydrant. If laying 2-threes, than eng is hooked to hydrant.

We run 2 eng. and a TL from one station. So first engine drops supply lines to second engine and goes for water. He then returns to become pump operator of second engine. Second due eng. operator (could be duty officer) and TL operator go in on first line.

Thats one reason I like the 5". We usually due reverse lay and if second due eng out of service, more than likely we don't have to worry about adaptors or reconfiguring the hose on the eng. Lots of work when there is anly three on duty and no garuntee when vollies will show up to assist, and MA is a few minutes out.

The other reason is MA. All surrounding depts. have 5" and don't have to worry about adapting fittings. Some are NS threads and some use FDNY threads.

23. Originally Posted by Frosty42
Gotta love 5" supply lines. I only hate it when.....

1. No hose bed covers=lots of hose on the interstate
Amen Brother!!!!!!!!!

People do crazy things when they see 800'-1000' of 5" whipping/rolling/falling in front of them at 70+MPH!!!

And then just TRY to page for volunteers to come help reload it.

24. ## Yes They Do..........

Originally Posted by cityfire7
Amen Brother!!!!!!!!!

People do crazy things when they see 800'-1000' of 5" whipping/rolling/falling in front of them at 70+MPH!!!

And then just TRY to page for volunteers to come help reload it.
Last Summer, my wife and I were on a short trip, and out in the middle of nowhere on the Interstate, we saw traffic was slowing, and seemed to be vacating the right lane. Getting closer we found a badly battered hydrant valve in the middle of the right lane, and a 5 inch line laid out from it. No apparataus to be seen anywhere. I jumped out and grabbed a few flares while my wife called the local dispatch center for Police and to get someone out there to pick up the hose. Another Firefighter passing through helped, and we pulled all 1,500 feet off onto the shoulder, PD showed up, but nobody knew who lost the hose. We found out later that it was from an Engine that was going to a repair shop about 20 miles beyond where the hose fell off.

25. ## 5" WHAT ELSE IS THERE?????

I have 3" on one department and 5" on the other. 5" blows 3" out of the WATER!!! At 400 GPM 3" loses 13 PSI per 100' and 5" loses a whopping 1 PSI. There I did the math for ya. Good luck I hope this will help the final word.

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