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  • 4" or 5" LDH

    Dept. currently runs with 4" LDH and there have been discussions concerning switching over to 5".

    As for hydraulic calcs, most engines are 1500 gpm single stage pumps. Area is provided with hydrants and largest water mains are 12". Pressures on mains fluctuate based on seasonal demand and static pressures vary from 65-100 psi.

    Community is largely residental and good mix of commercial. Most buildings are type 3 construction and provided with fire sprinklers.

    Based on water supply, fire pump capabilites and building construction, is it realy worth the expense to switch from 4" to 5" hose?

  • #2
    Look back at past fires....

    have your engines been running short of water?
    do you lay in from the hydrant directly or are you on a humat and an engine pressurizes the hydrant?
    are you laying long stretches or under 1000'?
    what GPM from the hydrants is possible? All of mine give the same PSI but due to main sizes, flow from 500 up to 2000gpm.
    is mutual aid compatibility a concern? I doubt it, but it may/may not require adapters.


    Just a couple other things to discuss...
    "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?

    Comment


    • #3
      How about putting it this way. If purchasing LDH is there ANY reason to buy more 4" rather than stepping up to 5". Tremendous benefit to buying 5" if you are laying any distance at all.

      A few 4" to 5" adapters is a trivial expense if you end up with a mix of 4" and 5" for a few years. And make sure the 5" is on the hydrant not at end of the lay.

      Our LDH is 6" and we have 6"-5" Storz adapters as our mutual aid depts have 5" LDH.
      Last edited by neiowa; 09-07-2006, 02:58 PM.

      Comment


      • #4
        either 4 or 5

        Long lays..........nah. Most of the times not more than 500-600 feet at best. Hydrants located for the most part not more than 750 ft. apart, unless on a court or cul de sac.

        Running 4 and 5 together as a mixed load.....not good idea. Keep it simple. Each engine runs with 1200 ft (1000 in bed, 200 rolled in compartment).

        Replacement costs not a issue. Funds can be found or budgeted.

        Issue in my mind is this.......is there enough water in the Municipal system to justify going with 5 inch? My thinking is we can currently maximize the 4 inch (flows, gpm, etc)whereas will we only use "xyz" percentage of the capabilites of the 5 inch? With the problems with water restrictions in the spring and summer and the fluctuations in available water supply due to demand, is it prudent to consider going from 4 to 5 inch LDH?

        Past experience shows that if a single 4 inch lay don't cut it, drop another line. SOP's dictate forward lay for first due engine. No Humat/hydrant assist or engine on the hydrant. Just a "cold" water line from hydrant in to the job.

        Comment


        • #5
          Using the "x % of available" reasoning is a bad idea IMO. If you have a poor water system you want to use larger hose so as to not make a bad situation worse by excessive friction loss. In other words the flows encountered in ANY structure fire can make 5" a benefit. Remember we calculate available water at 20 psi residual system pressure so that means that if you are pulling the max system capacity you will only have 20 psi at the START of your hose lay and so you cannot afford to have more than 5-10 psi friction loss in the hose lay itself at the very most.

          Myself, I would just buy 5" hose, not mix them between engines, but I would probably not throw out anything either, I know money is tight.

          Also I would not base this kind of decision on past experience, I would pre-plan some of your larger commercial occupancies and consider what kind of water would be required vs how much pressure and flow would be available and see how that 4" would do in that situation.

          Birken

          Comment


          • #6
            If cost is not an issue, then there is no decision to me. No reason not to go to the 5". You won't overtax the water system and it will give you the added benefit of less friction loss (although minimal on 4").
            "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?

            Comment


            • #7
              Originally posted by Bones42
              If cost is not an issue, then there is no decision to me. No reason not to go to the 5".
              I agree, but let's look at your 500' lay at a few different flows and see what happens (numbers rounded off to nearest 5's)...

              We'll assume no supply engine on the hydrant, as you said was your SOP.

              @ 500 gpm over 500', you'll have 25 psi loss in the 4" and 10 psi loss in the 5". As long as your hydrant has a flow pressure of at least 45 psi, you're fine.

              @ 750 gpm over 500', you'll have 60 psi loss in the 4" and 25 psi loss in the 5". Now, you need a flow pressure of at least 80 psi on the hydrant to support the 4" lay, but only 45 psi for the 5".

              @ 1000 gpm over 500', you'll have 100 psi loss in the 4" and 40 psi loss in the 5". Now, you need a flow pressure of at least 120 psi on the hydrant to support the 4" lay, but only 60 psi for the 5".

              So, for most evolutions where you're using just a couple of handlines, you'll be fine either way. But, when you need bigger flows (or longer distances), the larger LDH really becomes an advantage, especially if you're operating without an engine on the hydrant (either by necessity or choice).

              If you flip this around and put a supply engine into the picture, consider this...

              With 4" tested at 200 psi and an operating residual of 20 psi, you can move 1000 gpm a maximum of 900' over flat ground (and just barely - 800' is safer). With 5", you can move that same 1000 gpm over 2000', or you can move 1500 gpm (if you could find it) over that same 900' of flat ground.

              So, I concur...if you have the money, get the 5" and give yourself some added flexibility.

              Comment


              • #8
                Originally posted by ajmcfm

                Running 4 and 5 together as a mixed load.....not good idea. Keep it simple. Each engine runs with 1200 ft (1000 in bed, 200 rolled in compartment).
                Probably correctly but 4" on one engine and 5" on another engine is OK if you provide yourself with appropriate adapters.

                Comment


                • #9
                  Personnally, I would stick with the 4". With the lays under 1000', the additional water will not be substancial, especially if you have plentiful hydrants where another line can be laid from in short order. 5" is most effevtive in long lays, low pressure-high flow water systems, rural LDH operations and situations where a engine is not available to pump the hydrant, which brings me to .....

                  I would make a suggestion though, if water is an issue. Buy a 4-way valve for each engine. This will allow the initial line to be laid and charged from the hydrant by the first in engine, and then a second engine can be sent to the hydrant to pump the line. This can make a big difference in your flow through the 4" as my former department in VT used this technique to boost flow and found it to be very effective.
                  Train to fight the fires you fight.

                  Comment


                  • #10
                    I'd go 5". Basically a 1000 gpm pumper cannot flow capacity over 650ft through 4" LDH due to friction loss and exceeding 165psi engine pressure. Using 5" you can flow 1000 gpm more than twice as far. Yeah, most jobs you'll not need the big flow, but when you do, look out it will be critical to exposure protection and good defensive ops. Or you could do like most places and wait until the ifre burnes down to a size your gpm can handle.

                    Comment


                    • #11
                      Originally posted by ajmcfm
                      Running 4 and 5 together as a mixed load.....not good idea. Keep it simple. Each engine runs with 1200 ft (1000 in bed, 200 rolled in compartment).
                      This one single statement holds the key to the biggest single thing you could do to make things easier on yourself. Forget the 4" and 5" stuff for a second.

                      If you really want to help yourself and drivers, get rid of those 100' sections of 4" or 5" hose in the compartment and replace them with 33' sections.

                      We carry 1066'. 1000 in the bed and (2) 33' sections. When you put it on the ground and come up 10' short it will be MUCH easier to complete the lay with a short section than unrolling or pulling off another 100'.

                      The basic rule we follow is if it looks like you are 50' short or less, use both short sections to complete the lay. Over 50', pull another 100' out of the bed.

                      Amazing how much time and energy you will save. Regardless of the hose you end up with, 4" or 5", getting some water faster is better than waiting with no water.
                      RK
                      cell #901-494-9437

                      Management is making sure things are done right. Leadership is doing the right thing. The fire service needs alot more leaders and a lot less managers.

                      "Everyone goes home" is the mantra for the pussification of the modern, American fire service.


                      Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

                      Comment


                      • #12
                        Originally posted by LaFireEducator
                        Personnally, I would stick with the 4". With the lays under 1000', the additional water will not be substancial, especially if you have plentiful hydrants where another line can be laid from in short order. 5" is most effevtive in long lays, low pressure-high flow water systems, rural LDH operations and situations where a engine is not available to pump the hydrant, which brings me to .....
                        This is certainly true, but if cost is not an issue, why not add flexibility for the low-prob, high-risk events. Some examples of where this could come into play...

                        1. As I type this and until further notice, our tanker (3500 gals with 700' of 5") and engine (2000 gpm with 1800' of 5") have been bumped up from first alarm to initial structure response on a new, fully hydranted housing development in the next district. Why? Because now that it's becoming occupied and people are trying to use the water system, it turns out that the combination of municipal planners/water company/developer didn't arrange for sufficient water capacity in the development for some domestic use, let alone firefighting. All of a sudden, they need that 2500' of 5" LDH we carry (or tankers) to help make the kind of lays they'll need in the event of a fire. Our job would be harder and we'd need even more apparatus assigned if we all had 4" instead of 5".

                        2. Several years back, for both LDH and tanker coverage, we were added to responses in the fully hydranted Reading suburbs several miles away for a few months. Why? Because the earthquake strong enough to damage infrastructure that never hits Pennsylvania didn't get the memo, and went ahead and hit Pennsylvania anyway, cutting their water supply in a whole bunch of places. Again, long lays to either static sources or uncompromised water systems were needed, and 5" was a big advantage.

                        My point is that it's those high-risk/low-probability events that getcha, and if you have the financial resources, why not have the extra capacity to handle them?? Mind you, I'm not suggesting huge investments in all kinds of fancy apparatus you'll never use, just a couple grand extra for one extra inch in diameter on hose you're gonna use anyway.

                        Originally posted by LaFireEducator
                        I would make a suggestion though, if water is an issue. Buy a 4-way valve for each engine. This will allow the initial line to be laid and charged from the hydrant by the first in engine, and then a second engine can be sent to the hydrant to pump the line. This can make a big difference in your flow through the 4" as my former department in VT used this technique to boost flow and found it to be very effective.
                        If you're going with 4", that's certainly good advice.

                        Originally posted by MemphisE34a
                        If you really want to help yourself and drivers, get rid of those 100' sections of 4" or 5" hose in the compartment and replace them with 33' sections. The basic rule we follow is if it looks like you are 50' short or less, use both short sections to complete the lay. Over 50', pull another 100' out of the bed.
                        This is also excellent advice, and we do much the same thing as is described here.

                        Comment


                        • #13
                          My two cents.......

                          I currently work for a Department that uses 5" hose...... and we have to have a "football" that we have on all LDH beds. We are trying to go to 4" with a 4" to 4 1/2" adapter since we have hydrants that have both 4" and 4 1/2" steamer ports. Some reasons why are FF safety (having to carry 4" is easier on your shoulders and back, than 5"), money (both initial buys and replacement) and room in the hosebed.
                          Personally, we have lots of hydrants that are a great water supply and I think that 4" is sufficient enough, especially from one hydrant. If you need more water than that I suggest bringing water from a different water main.
                          Ultimately, it depends on your fire flows needed, availability of manpower, Management's opinion (come on let's be honest here) and the capabilities/needs of your Department.
                          "Be LOUD, Be PROUD..... It just might save your can someday when goin' through an intersection!!!!!"

                          Life on the Truck (Quint) is good.....

                          Eat til you're sleepy..... Sleep til you're hungry..... And repeat.....

                          Comment


                          • #14
                            Ultimately, it depends on your fire flows needed, availability of manpower, Management's opinion (come on let's be honest here) and the capabilities/needs of your Department.
                            Okay, reasonable bottom line, but....

                            Originally posted by mikeyboy
                            Some reasons why are FF safety (having to carry 4" is easier on your shoulders and back, than 5"),
                            Let's face it - you shouldn't be carrying LDH, no matter what size - 110 lbs isn't easy on your back, but 90 isn't much better. In reality, you should never have to carry 100' lengths of LDH: supply line can be drained an re-packed without ever breaking the couplings or lifting more than 10' at a time; make-and-break operations can be done with 25-50' lengths; and lower flow operations (tank fills, etc) can be accomplished with 2 1/2" or 3" hose. If a new 100' length is being added, or if you have to roll an old one to take it out of service, use a dolly.

                            money (both initial buys and replacement)
                            When you consider the overall cost, it's not really that much of a difference between 4" and 5". Especially if you eliminate the need for a hydrant assist valve, etc, by going to 5".

                            and room in the hosebed.
                            It all depends on what brand you use and how you pack it. When we switched from 4" to 5", we were able to put 3200' of 5" in the same hosebed that previously held 2000' of 4" - simply by carefully loading couplings at the front of the bed and staggering folds. This was with Angus Hi-Vol 5", the highest flowing hose on the market.

                            Personally, we have lots of hydrants that are a great water supply and I think that 4" is sufficient enough,
                            That may be the case, but fire departments' perception of "sufficient" is often based on those 95% fires that only cause 5% of the damage - and they don't take into consideration of the remaining 5% that cause 95% of the damage.

                            especially from one hydrant. If you need more water than that I suggest bringing water from a different water main.
                            If you need to hit another main to get enough water, that may be enough reason in itself to buy bigger hose - if you need to go farther away to get the water, you will need bigger hose to overcome the friction loss created by the extra distance.


                            Again, I don't know your department's operations, so 4" could work fine for you. I just think you need to be careful about your rationale for making this decision.

                            Comment


                            • #15
                              Originally posted by RFDACM
                              I'd go 5". Basically a 1000 gpm pumper cannot flow capacity over 650ft through 4" LDH due to friction loss and exceeding 165psi engine pressure. Using 5" you can flow 1000 gpm more than twice as far. Yeah, most jobs you'll not need the big flow, but when you do, look out it will be critical to exposure protection and good defensive ops. Or you could do like most places and wait until the ifre burnes down to a size your gpm can handle.

                              This is only true at draft with ONE suction line (or 2 if you have a 2000+ GPM pump). Working off a pressurized supply (hydrant) your 1000 GPM pumper can probably pump 1500+ GPM if you use the pump and hose right and it can certainly pump 1000 GPM more than 165 PSI if the incoming pressure is sufficient.

                              Assuming my math is right...

                              The max you can move 1000 GPM is at 185 PSI in supply grade LDH for a total approximate distance of 825 feet in 4" and about 2050 feet with 5" hose.

                              If you are drafting with that 1000 GPM pumper your 4" will give you 1000 GPM @ about 725 feet pumping at 165 with 20 residual. The 5" will give you about 1800' of distance with 20 residual.

                              Alot of people will read this an say "thats crap, nobody can remember that." We made a chart that shows the supply line pressures/FL's and keep it in the rig.
                              Last edited by MG3610; 09-16-2006, 10:17 PM.

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