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  1. #1
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    Default Jet Siphon Assisted Dry Hydrants

    Our department is considering options to supply water to a small housing development in an otherwise very rural area. The main idea being considered at this time is a dry hydrant, but it would need to be located at least 250 feet from the lake with an 18 foot lift to the pump. Not only do I question the long horizontal run, but I'm extremely concerned about the vertical lift. Does anyone out there have any experience with this type of setup? Would you locate a jet siphon at the inlet or where the pipe turns vertical? Any other ideas?


  2. #2
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    We have a similar setup in one of our areas that is remote from our otherwise strong public water system. It's quite unique, and unfortunately, I don't have any pictures of it. Ours is in a creek that has varying water levels and is prone to debris floating by, so we actually have to attach sleeves on both ends. Nevertheless, we can get in excess of 750 GPM from it. The horizontal travel is of minimal consequence as long as you use a large enough diameter pipe, free of too many tight turns. It would take quite of time to prime the pump.

    We did give some thought to using a jet siphon, but for a variety of reasons unrelated to the operation of the unit, discarded it. The location requires carrying equipment down a steep rocky trail. Getting the sleeves to it is quite a chore, so carrying the heavy siphon unit to the same place would be, we think, risky at best. Still, it would be nice to see how it would do. One unit is made locally, and we were thinking of inviting them to demonstrate it there.

    I'd be interested in knowing how you make out with it if you decide to do it.

    Stay safe out there, everyone goes home!

  3. #3
    Let's talk fire trucks! BoxAlarm187's Avatar
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    Although we've thought about a setup like this, we haven't taken the time to evaluate it's effectiveness. I'll watch this thread carefully.

    As for the hoizontal distance, one of the dry hydrants in our district is 300' from the water source. Now, unlike your vertical lift issue, our vertical is only 8'. Nevertheless, the 300' length has never proven to be a problem for us.

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    Quote Originally Posted by mongobob
    it would need to be located at least 250 feet from the lake with an 18 foot lift to the pump.
    Is the horizontal run relative flat? If so, not a problem.

    Let's assume that you can trench and lay the PVC piping relatively flat. Mother Nature will fill the pipe with water for you. All you have to do is lift it the last 18 feet. That shouldn't be a problem for a well maintained pump.

    If the trench is on a slope and most of the pipe will be dry, that's another issue. You can draft but you'll need more priming time to evacuate the air in the pipe. Some engine run dual priming pumps just for that reason. Haven't seen any permanent turbo-draft style devices for dry hydrants yet.

    Good luck!
    Remember, it IS as bad as you think and they ARE out to get you!

  5. #5
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    Quote Originally Posted by Jim917
    Is the horizontal run relative flat? If so, not a problem.

    Let's assume that you can trench and lay the PVC piping relatively flat. Mother Nature will fill the pipe with water for you. All you have to do is lift it the last 18 feet. That shouldn't be a problem for a well maintained pump.

    If the trench is on a slope and most of the pipe will be dry, that's another issue. You can draft but you'll need more priming time to evacuate the air in the pipe. Some engine run dual priming pumps just for that reason. Haven't seen any permanent turbo-draft style devices for dry hydrants yet.

    Good luck!
    The horizontal run would be flat and underwater. Not being an engineer, I invision it in 8 inch diameter PVC. I would think the vertical would be reduced to 6 inch to lessen the weight of the water being drafted. I know a good pump should pull 21 to 22 feet, but the reality of everything being that perfect in an emergency situation is questionable at best. If a jet siphon can be added for extra security, I'm sure it would be worth the expense (which is probably minimal). I would like to hear from someone that has seen a system like this work. I don't like being the guinea pig!

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    Quote Originally Posted by mongobob
    I don't like being the guinea pig!
    Oh, but you are!

    Stay safe out there, everyone goes home!

  7. #7
    Forum Member Bones42's Avatar
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    I'd be more concerned with the underwater 250' horizontal run getting plugged up with silt and/or debris. You'll have to make sure it's maintained to avoid that happening.

    Is there any road access to that lake 250' away? If so, I'd rather just do a reverse lay from the scene to that point and setup a normal draft. Of course, if there is no road access....

    PS - we have a 50' dry hydrant setup that is unusable due to non-maintenance. It's plugged solid.
    "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?

  8. #8
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    Quote Originally Posted by Bones42
    I'd be more concerned with the underwater 250' horizontal run getting plugged up with silt and/or debris. You'll have to make sure it's maintained to avoid that happening.

    Is there any road access to that lake 250' away? If so, I'd rather just do a reverse lay from the scene to that point and setup a normal draft. Of course, if there is no road access....

    PS - we have a 50' dry hydrant setup that is unusable due to non-maintenance. It's plugged solid.

    We have a couple of other dry hydrants. When we hook up to them for training every year, the first thing we do is back flush them with the booster tank water. Like anything else, they need to be maintained.

    Also, there is no access to the lake. That's why we need such a long horizontal run. The DNR has their own logic, but at least they make the permit process for the hydrants relatively easy.

  9. #9
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    Contact: Larry Davis <rfofire@stx.rr.com> He wrote the book on rural water supply including dry hydrants.

  10. #10
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    Quote Originally Posted by mongobob
    Our department is considering options to supply water to a small housing development in an otherwise very rural area. The main idea being considered at this time is a dry hydrant, but it would need to be located at least 250 feet from the lake with an 18 foot lift to the pump. Not only do I question the long horizontal run, but I'm extremely concerned about the vertical lift. Does anyone out there have any experience with this type of setup? Would you locate a jet siphon at the inlet or where the pipe turns vertical? Any other ideas?
    One solution would be to install at "wet well" as your draft point. The PVC dumps into the wet well and you draft from there using your suction hose. 8" is a good size for a "normal" dry hydrant (6" being miminal recommended). I'd suggest using 12". Your wet well could be a concrete structure (as used in the sewer or storm water business) or as simple as a vertical pipe off your horizontal run. 12" is sufficient to keep you suction hose supplied.

  11. #11
    Forum Member nmfire's Avatar
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    I echo what others have said about junk building up in the pipe. If you have a reletively level horizontal run that is below water level, it will have water in it all the time. All the crap in the water will settle in the pipe... mainly sediment, dirt, and anything else that floats or swims into it. I would make a regular thing of backwashing it once a month or something to make sure it stays clean.

    If it is a sealed up properly, a good primer pump should have no problem with it. Although now that I say that, I did manage to sieze the primer pump on our tanker last week, and that was with the truck parked next to the pond and it only ran for about 10 seconds.
    Even the burger-flippers at McDonald's probably have some McWackers.

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