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4" or 5" LDH - any advantages of one over the other?

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  • 4" or 5" LDH - any advantages of one over the other?

    What advantages, if any, are there to using 4" vs. 5" Large Diameter Hose?
    Any advantages to using one size over the other in terms of cost, friction loss, ease of use, amount of water that you can move, etc.
    Although the Town of Lyons has hydrants we rely on tanker (tender) shuttles to supply the majority of our rural district.

    Captain Michael Guy
    Lyons Fire Protection District
    Lyons, Colorado

  • #2
    2 things friction loss and volume:
    Now somebody will correct me where I am wrong
    -you have to look up for yourself, probably out of an IFSTA manual the differences in friction loss per 100ft of each size.
    -volume ~1000gpm for 4" and ~1500gpm for 5"
    it all depends on your required/capable water flow.

    Keep Safe!


    • #3
      Jizumper is right on in terms of operational considerations Volume/Friction loss will be considerably more favorable to you with 5" hose.

      Both 4 and 5" hose are capable of supplying significantly more water than the 1000 gpm/1500 gpm mentioned.

      Here is another way of looking at it. Lets assume that you want a flow of 1500 gpm (thats the size of your biggest pump) and that 100 psi is the average pressure you hydrant will provide that water.

      You would expect the FL to be 45 psi in the 4" and 18 psi in the 5". Consequently you will only be able to drop two lengths of 4" from the hydrant and with 5" you can get closer to 500' of drop.

      In terms of volume flow the 5" apples to apples should not quite double the flow as a rule of thumb.

      In practical terms they are both heavy, cumbersome and fixed to the ground when charged so why not use the larger diameter. Yes the 5" is more work, but it seems to be a 'low' cost upgrade if you are starting from zero.

      Good luck


      • #4
        I agree with both of the statements above. The thing about 5 inch hose is that you can get adapters, I believe, to connect to a 4 or 4 1/2 inch connection. I prefer to use 5 inch but that is just my opinion. Stay safe!

        *These are the opinions of me and only me and have nothing to do with what my company thinks.



        • #5
          > you can get adapters, I believe,

          Yup. We use 4" supply. Our neighboring FD, South Windsor, uses 5". We have adapters on our trucks so we can connect to their hose.


          • #6
            //the Town has hydrants we rely on tanker (tender) shuttles to supply the majority of our rural district.

            It might just be that 4 or 5 inch hose might be the wrong size. The 2nd best rural ISO ratings (Class 4)in your state Rattllesnake 55 miles from you uses 3 inch. The best (Class 3) Dolores uses 5" but could have done the same with 3". The 3rd best Loveland 21 nmiles from you also a Class 4 used 5". The next Class 4 in your state Berthod 14 miles from you will be using 3 miles of 5 inch.

            These folks have some serious rural weater supply knowlege going from A class 10 to a Clas 3 in one step, Two others going from 9/10 to a Class 4 in one step and and the last 9 to a 4 all at once. You are looking at $200 to #3100 a year savings on insurance every year on every home for the net 15 years if you do it right.

            n of the FD's used cisterns and a pond, one used a river, another used the town hydrant systems and the last one only had one hydrant in the entire district. So there are no obsticles that have not been overcome in your state as it applies to rural water.

            When you present the potential savings don't be surprised if the public triples your department like they did in Berthod. Or doubles your tanker fleet 10 minutes from the time they hear about it even though you are not on the agenda like happened in Loveland. Or quintuple your operating budget like happend in Dolores. Or 92% of the voters vote for your plan to replace your entire fleet and increase the size of all your stations, add a station, solve your water point needs and buy you a totally star wars fleet of CAF pumper tankers like happened in Rattlesnake. Or like Animas who covers 10,000 people have the voters authorize 5 more stations and 21 new fire trucks and increase the operating budget 1/2 million a year in just a few months.

            If you've got needs the insurance system will help you solve them as fast as you can move.

            86 of the towns in Colorado have the worst possible ratings of Class 9 or 10. SO there is plenty of money. All but 11 of the 598 fire departments in the state have Class 9 rural ratings. What a shame.

            What size hose? It all depends what you intend to do with it or not do with it. I know Class 4 rural department that used 2 1/2" hose and a 1957 500 gpm pumper.

            Your needed fire flows, distance needed to move water, whether hose will be used to move the water, and the size of the pump that will do the moving.

            SO tell us, what are your intentions? Do you have a plan? Share it with us.

            [This message has been edited by LHS* (edited 05-25-2001).]


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