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4inch or 5inch?

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  • 4inch or 5inch?

    I need some input on the differences of 4 and 5 inch LDH. Fire flows, supplying aerials, friction loss, etc.. We are getting a new ladder truck and I need more info from a unbiased source. Thank you.

  • #2
    4"-1000 gpm
    5"-2000 gpm

    Like I have said before see what other depts around you use and how your hydrents are set up there,being some what common with the other guys may reduce the chances of needing to find that one special adapter at 2:30 am.
    From my expierince I have found storz fittings better to work with as your not chaseing the male or female end or you pack 1000' of 5" steamer connection and find the fittings are in the wrong positions. Also check to see what your rated pump capacity is and what kinda of general pressure and gpm's are avalible from your "average" hydrent in town.

    My dept. has a excellent water system and uses 4" and it works great for us as where two towns over they have no hydrents and use 5" for tanker feed and carry alot of adapters to reduce to 4 inch in all other towns.

    good luck


    • #3
      A little more info. Two neighbouring depts. use 4inch one still uses 21/2inch supply. Our coverage varies from no hydrant coverage to industrial where we get big water at up to 120psi. How much is big water? We currently use 4inch supply fed into a 1050gpm pump so I have no idea. I need solid facts to bring to the apparatus commitee so a link or a reference to a text would be appreciated.


      • #4
        The guy to talk for exact stuff is BLACKSHEEP on here, he wrote a manual on hydraulics that blew my little explorer head right off with facts and infomation!!!! If you need specifics he is the one to talk to.


        • #5
          Try www.akronbrass.com. They have a chart that shows the friction loss per 100' for various size hose at various gpm. click "NEWS" and then "Technical Data" and look for the Friction loss in fire hose.

          What is the average and maximum supply line length that you will lay?
          What is the hosebed capacity of your truck?
          Is cost of the hose a factor?

          Go with Storz couplings as previously mentioned. Less adapters and you never have the "wrong end" of the hose.

          Also note that LDH couplings do not like to "turn" corners coming out of the hose bed. It must be loaded so that it is a "straight pull" for the couplings or they will hang up. This problem is most common on rear mount aerials where the hose bed curves around the turntable housing.

          Stay Safe
          Last edited by Rayr49; 06-05-2003, 12:33 AM.


          • #6
            Uhhhh...Oops! My FD uses Storz on all LDH I didn't even think about threaded couplings. The hydrants in the industrial area are no more than 500' apart. LDH hosebeds are 1000' feet on our current fleet. The new truck will be a Smeal with the rollout hosebed so no bends around the turntable. What if we kept the 4" and split the load into 2 500' lengths? We could then use it as a double lay from a hydrant or a single from two hydrants. If the lay was over 500' feet the two could easily be coupled together. Thoughts on this?


            • #7
              Is this a quint or dedicated ladder?

              Do you have suffcient water and pressure from one hydrent to supply two 4" lines?

              Do you use a Humat valve or a portable hydrent as your normal hydrent lay SOP?

              If you used both hydrents would you have enough resdiuale pressure/gpm to supply two 500' 4" lines?

              I personally would keep it at 1000' for easier lays. With storz it is easy enough to break if needed.

              Our trucks we dress the hydrent with the 4" and 2x 2.5" gates and hook the 2.5 up to them. We send water with just the 4" and that usally supplys our needs pretty well if more is needed then we open the 2.5".
              Last edited by dfdex1; 06-05-2003, 02:51 AM.


              • #8

                My Department utilizes 6000' of 5-inch LDH on 3 Different Pumpers and a Utility/Support Vehicle. E-mail me
                and I can give you any useful information you might need as far as LDH is concerned. If you are local or on the eastern seaboard, you are also more than welcome to come down and observe the different things you can do with LDH. I despise using the 5 inch because it it such a Pain to re-pack and move around, but for fire flow, it works very well and you can move a hell of a lot of water.

                My Department is the Dedicated "Water Supply Unit" for our Entire County. We roll on all 2nd alarm or greater jobs countywide. We can use the 5-inch for Rural or Urban water-supply. It has few limitations.

                [email protected]

                you are gonna have to type it manually because FH.com breakes the E-mail address up. Who knows why...
                Last edited by TillerMan25; 06-05-2003, 02:47 AM.
                Proud Right-Wing Extremist since 1992

                "Extreme Liberalism is a Mental Disorder"- Michael Savage


                • #9
                  Do you have suffcient water and pressure from one hydrent to supply two 4" lines?
                  By that I meant a single 4" and 2x 2.5" into a 4" siamese. Wouldnt let me edit thats why I posted again.


                  • #10

                    5" is the only way to go.... It is like laying a water main on top of the street, The friction loss is negligible. NEIDNER hose makes a lightweight, double jacketed, lined synthetic LDH. The weight comparison is hugely different. 100' section of NEIDNER 5" is 96.5 pounds with couplings as compared to 125-130 for rubber LDH. It also packs much better and allows you to get more in the bed. Since it is synthetic and ENCAP treated it is resistent to mildew and also abrasion.
                    09-11 .. 343 "All Gave Some..Some Gave ALL" God Bless..R.I.P.
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                    The comments, opinions, and positions expressed here are mine. They are expressed respectfully, in the spirit of safety and progress. They do not reflect the opinions or positions of my employer or my department.


                    • #11
                      Thank you all for taking the time to post. This truck will be a quint. As to flows from hydrants I will be talking to someone who has knowledge of this. No Humat, but once I have all the information possible this may be a future purchase. captstanm1 if we currently have 1000' of 4" on the trucks how much 5" could you stuff in that space?


                      • #12
                        Why would you not get 5"? It gives you much less friction loss, it gives you future capabilities, it gives you more chances to get the most water. Even if your water supply system can't give you more than 800gpm, why not put that 800gpm in the bigger line? The cost is going to be a little different, but in the end, it most likely will pay for itself. Your dual 4" lines from 1 hydrant will be easier with 1 5" line and I'm guessing the hydrant probably won't give you much more than 1500gpm at most (wish I had a hydrant that would give me that much).

                        From snap-tite web site:
                        Friction loss on 4" at 500gpm = 3 lbs per 100'
                        Friction loss on 5" at 500gpm = 1.1 lbs per 100'

                        Friction loss on 4" at 1000gpm = 11.9
                        Friction loss on 5" at 1000gpm = 4.1
                        "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?


                        • #13
                          Try www.akronbrass.com. They have a chart that shows the friction loss per 100' for various size hose at various gpm. click "NEWS" and then "Technical Data" and look for the Friction loss in fire hose

                          That chart, like the others you see in fire service publications like IFSTA & NFPA, is hopelessly outdated.

                          The charts where written in the 60s if not earlier for double cotton jacketed, rubber lined fire hose. They may even be relevant if you buy low bid hose. They're not relevant if you pay attention to what your purchasing!

                          Since the 60s, we've improved jacket construction, liner materials, and the bonding of the liner to the jacket.

                          Angus' Hi-Vol line of nominal 4" & 5" hose the jacket allows it to expand to 4.2" and 5.2" when charged. Plus the material is slipperier than rubber. The "chart" says 4" has a coefficient of friction of 0.2 and 5" has a C of 0.08. Hi-Vol comes in at 0.1 and 0.034 respectively -- over twice the performance of the charts.

                          Ponn Conquest similiarly radically outperforms the handline friction loss found on the charts. Their polyethelyne liner is much more slippery than rubber. Plus it's injected into the inner jacket, so it doesn't take as much room allowing the inside diameter to be larger than the nominal size of the hose.
                          IACOJ Canine Officer


                          • #14
                            Do the logical thing. If it's for the ladder....most likely, you're going to be flowing BIG water....so, why not go with the larger hose?

                            The difference in friction loss alone is reason enough to step up to 5 inch.

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                            • #15
                              While the 5" can move double the water the 4" can (2000 vs 1000gpm), it really pays off when running at the lower flow rates which are more typical for a rural or older hydrant system water supplies and this may be the easiest way to convince the powers that be to pay for it.

                              At 1000gpm you can lay 2300 feet w/o a relay pumper (assuming 180psi pump pressure and 20psi residual and no elevation loss/gain). Single 4" over that distance and at that flow rate would require 4 pumpers (in other words, you could only lay 800 feet with a single pumper). If you are running shorthanded this pays off big time, that's 3 trained firefighters who can go to the scene instead of running a pump. If you lay dual 4" you have to pick up twice as much line at the end of the day, who wants to do that?

                              It does takes up more of the hose bed and you end up with less of it on the truck (it's a trade off). Our quint tower could carry 1000' of 4" only carries 800' of 5". You could also just spec your truck to carry 1000' of 5" if it is not already built.

                              So even if you don't have a single pumper over 1000gpm, 5" LDH pays off "in the long run" litteraly. Carry a pair of 4"-5" adaptors and possibly a gated wye (with storz it could be a wye or a siamese) 4"-5" to maximize flow if you have smaller pumps or if forced to extend with 4" from other trucks/mutual aid.
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