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  1. #1
    Captain Mike
    Firehouse.com Guest

    Post 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
    Dalmatian90
    Firehouse.com Guest

    Post

    For most applications, go with the 5" if you can.

    5" costs a bit more.
    It also moves more water farther all other things equal. Even with weak water supplies, it will move what you do have farther with less pressure loss.

    Get the actual friction loss ratings from different fire hose manufacturers. It can make a huge difference. For instance, traditional fire service charts list 4" having a FL of 45psi/100' @ 1500gpm and 5" having a FL of 18psi/100' @ 1500gpm. Angus Hi-Vol 4" is rated at 20psi/100' @ 1500gpm and Hi-Vol 5" is rated at 8psi/100' @ 1500gpm.

    That means Hi-Vol can move the same water twice as far the old friction loss charts would calculate. Also means if for whatever reason you decide to go with 4", go with a high-end 4" like Hi-Vol which is much more efficient!

    Possible Advantages of 4"

    -- Slightly more manageable on the fireground if used to supply master streams, etc. It weighs about 9lbs/ft when charged compared to about 13lbs/ft for 5" if you need to move it a few feet.

    -- If using as part of the dump-site to fire scene evolution in a tanker shuttle, 4" strands 1 gallon/foot of water, while 5" strands 1.6 gallons/foot of water. Have a 1000' lay? It'll take 1000 gallons to fill 4" and 1600 gallons to fill 5".



  3. #3
    M1NFD
    Firehouse.com Guest

    Cool

    I worked a town with 5" for 10 years. It was hydranted with good flow. I now work in a town with no hydrants,and 4". I prefer the 5 still over the 4, as your basic thought for supply line is going to be what will move the most water most efficiently. As far as workig and handling, full they are both too heavy to deal with, so no difference there. Flow, 1000gpm for 4 2000 for 5. Thats a HUUUUUUUGE benefit. You might have to give more thought to initial water supply if you get into long lays, but like anything else, you have to make what you use work for your manpower/staffing/ability to fill the hose. Where we are(my chief and I disagree) we would lay a 4" line, potentially up to 1000', that would wipe out one pumper(we all have 1000 gallon tanks here) Our tanker is 5600 gallons, so on a first alarm we roll out with 8600 gallons, and if we know we have a fire, we get our cover companies on the road and coming earlier, this way they can divert to tanker ops sooner. If we arent gonna get it with what we bring on the first alarm, they're usually gonna wind up there eventually.

  4. #4
    chiefjay4
    Firehouse.com Guest

    Post

    Twice as much water and barely any friction loss. Why take a knife to a gun fight?

  5. #5
    Junior Member
    Join Date
    Jun 2001
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    BFPD
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    Default

    There's only one reason I can think of for going 4" instead of 5", and that's compatability with everyone around you. I was on a department in a county where half of us had 4", half had 5" and everyone had a compartment full of adaptors for mutual aid. Otherwise go for 5".

  6. #6
    Banned
    Join Date
    Jun 2001
    Posts
    18

    Default

    Why would they have a compartment full of adapters when one, two or three 4 by 5 storz fitting would do everything? The fitting is the size of a frizbee.

  7. #7
    Junior Member
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    BFPD
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    Default

    We had three types of hose in the county: 5" Storz, 4" Storz, and 4" with national standard couplings (which I don't think you can even buy anymore). So thats a lot of adaptors. Perhaps not a compartment full, but I was using a bit of hyperbole there to make a point.

  8. #8
    Forum Member
    Join Date
    Dec 1999
    Location
    Swanton Fire Dept. Swanton, Vermont
    Posts
    474

    Default

    Buy what is correct for your department. We did not have LDH and had a 1750gpm engine on order, we bought the 5" LDH. The other departments have not had to by adaptors to work with us, we bought them!! Our rigs have the adaptors so they do not have to expend money and create hard feelings because of it.

    The 5" is big and heavy but it can sure move some water! Phase it in, buy 1000' to get started then, 500' a year for a while and you will get to what you need.

    Others have hit the high points of the advantages. The disadvantage of the 4" can be the limitations it creates on your supply. If you have a 1250gpm, you may be okay. If you have a 2000gpm pump, you better be thinking 5". If all you have are 1000-1250gpm engines, you may be able to get away with the 4". Your other issues can be needed fire flows.

    Just a few thoughts....

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