1. #26
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    Sure, everyone does that when they don't have LDH but the original question was about running LDH off the side ports. And one LDH will get you a lot more water than 2 3" with a lot less effort expended.

    Birken

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    Quote Originally Posted by BirkenVogt
    Sure, everyone does that when they don't have LDH but the original question was about running LDH off the side ports. And one LDH will get you a lot more water than 2 3" with a lot less effort expended.

    Birken

    Yeah, our is due to the fact that only half of our district has hydrants. The first due engines on the hydranted side have 4" supply while the first due on the non-hydranted side lay dual 3" supply. Thanks for all the information in this thread... especially fireh20... practical examples are just what I needed.

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    Quote Originally Posted by hwoods
    .....we NEVER (Yes, I said Never) connect a Supply Line direct to a hydrant, There is ALWAYS (yes, I said always) an Engine on the hydrant to pump the line.
    Just curious as to why you do this? Not enough hydrant pressure, long hose lays, etc? Do you usually do a forward lay from the hydrant or reverse lays to the hydrant??

    We have the first engine stop at the hydrant, forward lay to the fire. If we know a second engine is right behind the first one, then the second in engine drops the line to the first. Unless it is one of the few bad ones we are aware of, we always have more water than what we need from just static pressure of the hydrant. Maybe we are not using "big water" like you either....don't know.

    Just curious as to how you do it, thats all. not trying to start a schitt storm
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    Quote Originally Posted by Firetacoma1 View Post
    We had hydrant training last night and it made me wonder something... one of the teams instead of using the 4" output on the hydrant, used an adapter to hook the 4" supply line to a 2.5" discharge. What's the difference in flow between the 2... I argued that even with a 4" line, you're restriced by the 2.5 inch orifice of the hydrant... a bunch of the physics and engineer types thought it was neglible... I quickly shut up, but wondering if they're right?

    What's the flow with a 2.5" hydrant output adapted to flow through 4" hose?
    What's the flow with a 4" hydrant output to flow through 4" hose?
    The flow from the 4" will be 2.56 times greater than the 2.5", which is pretty significant. The outlet restricts the flow, even with LDH on it. You may not need that much water, but nobody ever got hurt because they had too much water available.

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    Interesting question and thank you. If memory serves, (always suspect) the friction loss of the 2.5 inch outlet from the barrel of the plug would be very little. You most likely would get at least 90% and perhaps a whole lot more. Perhaps even 98%? The 2.5 inch SIDE outlet discharge would flow just about as much as the 4 inch outlet.

    The GPM of the 4 inch hydrant outlet using a 4 inch hose would be dicated by the flow of the hydrant unless the plug flow is high enough that friction loss would instead dicate max flow through that 4" hose. Then that high GPM flow/pressure would determined by the friction loss per 100 feet of flow going through the aforementioned 4 inch hose.

    But ... and this may not apply here, if that 2.5 inch outlet is a "warf valve" or "corporation value" and is on top of the barrel, then the construction and type of that special case low flow outlet might directly and greatly restrict that 4 inch hose flow. Our wet type Class 1 West coast plugs had two 4" NS outlets on big mains and one 4" and 1 2.5" NS on most.

    Hope this helps. Long ago and far away. Respectfully to all. HB of CJ (old coot) retarded EN

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    Quote Originally Posted by HBofCJ View Post
    Interesting question and thank you. If memory serves, (always suspect) the friction loss of the 2.5 inch outlet from the barrel of the plug would be very little. You most likely would get at least 90% and perhaps a whole lot more. Perhaps even 98%? The 2.5 inch SIDE outlet discharge would flow just about as much as the 4 inch outlet.

    The GPM of the 4 inch hydrant outlet using a 4 inch hose would be dicated by the flow of the hydrant unless the plug flow is high enough that friction loss would instead dicate max flow through that 4" hose. Then that high GPM flow/pressure would determined by the friction loss per 100 feet of flow going through the aforementioned 4 inch hose.

    But ... and this may not apply here, if that 2.5 inch outlet is a "warf valve" or "corporation value" and is on top of the barrel, then the construction and type of that special case low flow outlet might directly and greatly restrict that 4 inch hose flow. Our wet type Class 1 West coast plugs had two 4" NS outlets on big mains and one 4" and 1 2.5" NS on most.

    Hope this helps. Long ago and far away. Respectfully to all. HB of CJ (old coot) retarded EN
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    Quote Originally Posted by HBofCJ View Post
    Interesting question and thank you. If memory serves, (always suspect) the friction loss of the 2.5 inch outlet from the barrel of the plug would be very little. You most likely would get at least 90% and perhaps a whole lot more. Perhaps even 98%? The 2.5 inch SIDE outlet discharge would flow just about as much as the 4 inch outlet.

    The GPM of the 4 inch hydrant outlet using a 4 inch hose would be dicated by the flow of the hydrant unless the plug flow is high enough that friction loss would instead dicate max flow through that 4" hose. Then that high GPM flow/pressure would determined by the friction loss per 100 feet of flow going through the aforementioned 4 inch hose.

    But ... and this may not apply here, if that 2.5 inch outlet is a "warf valve" or "corporation value" and is on top of the barrel, then the construction and type of that special case low flow outlet might directly and greatly restrict that 4 inch hose flow. Our wet type Class 1 West coast plugs had two 4" NS outlets on big mains and one 4" and 1 2.5" NS on most.

    Hope this helps. Long ago and far away. Respectfully to all. HB of CJ (old coot) retarded EN
    I'm confused. Are you saying that the 2 1/2" and the 4" outlet on the same hydrant are going to flow the same amount of water?

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    Quote Originally Posted by micahma View Post
    The flow from the 4" will be 2.56 times greater than the 2.5", which is pretty significant. The outlet restricts the flow, even with LDH on it. You may not need that much water, but nobody ever got hurt because they had too much water available.
    It's been nine years but I think you finally gave the OP a good answer. A very simple answer to his very simple original question.

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    Quote Originally Posted by captnjak View Post
    It's been nine years but I think you finally gave the OP a good answer. A very simple answer to his very simple original question.
    The difference is the restriction on a 2 1/2 discharge is minimal due to the length on the outlet. It is entirely possible with a hydrant discharge pressure of 20psi to get over 800 gpm out of a 2 1/2 inch discharge, over 1300 gpm at 50psi, and over 1600 gpm at 80psi. Of course this is all dependent on what the total flow the hydrant is capable of. It may not be equal to a 4inch discharge, or in our case a 4 1/2 inch discharge, but most of the time it is more than enough water if for some reason you can't make the steamer.

    So technically 2.56 is correct, but without knowing the hydrant flow capability it really doesn't mean anything of useful value.
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    Quote Originally Posted by FyredUp View Post
    The difference is the restriction on a 2 1/2 discharge is minimal due to the length on the outlet. It is entirely possible with a hydrant discharge pressure of 20psi to get over 800 gpm out of a 2 1/2 inch discharge, over 1300 gpm at 50psi, and over 1600 gpm at 80psi. Of course this is all dependent on what the total flow the hydrant is capable of. It may not be equal to a 4inch discharge, or in our case a 4 1/2 inch discharge, but most of the time it is more than enough water if for some reason you can't make the steamer.

    So technically 2.56 is correct, but without knowing the hydrant flow capability it really doesn't mean anything of useful value.
    I get your point and I agree.

    Another member (old coot) seemed to imply that the flows would be nearly identical. That I do not get.

    The Op basically asked if the difference between the flow of a 4" hose on a 4" hydrant outlet and a 4" hose on a 2 1/2" hydrant outlet would be negligible. He stated that the engineer types suggested it was negligible. I submit that the difference would not be negligible. He was indeed asking for actual volume numbers, which we can't give him. Although a lot of people tried and did so using hypothetical numbers. I kind of zoned out reading the responses because I'm not a big hydraulics guy. I'm just gonna stick with the difference being substantial, at least in all likelihood.

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    Quote Originally Posted by captnjak View Post
    I get your point and I agree.

    Another member (old coot) seemed to imply that the flows would be nearly identical. That I do not get.

    The Op basically asked if the difference between the flow of a 4" hose on a 4" hydrant outlet and a 4" hose on a 2 1/2" hydrant outlet would be negligible. He stated that the engineer types suggested it was negligible. I submit that the difference would not be negligible. He was indeed asking for actual volume numbers, which we can't give him. Although a lot of people tried and did so using hypothetical numbers. I kind of zoned out reading the responses because I'm not a big hydraulics guy. I'm just gonna stick with the difference being substantial, at least in all likelihood.
    Substantial to the capabilities of the hydrant, most often inconsequential to necessary fire flow for most incidents.
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    Quote Originally Posted by FyredUp View Post
    Substantial to the capabilities of the hydrant, most often inconsequential to necessary fire flow for most incidents.
    Yes, I've already said I agree with that.

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    Quote Originally Posted by captnjak View Post
    Yes, I've already said I agree with that.
    HOORAY!! We agree again!! LOL
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