1. #1
    Senior Member

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    Mar 2001
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    NF / Canada
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    Default Need info on in-line eductors

    We have 2 95 gpm eductors and I need some info on proper operation.
    -useing 1 1/2 line, max distance from truck to eductor?
    - max from eductor to nozzle
    - what psi should be maintained
    - how critical is it not to raise the nozzle 10 feet over the eductor? ( I found that # but we made foam with it higher than that)

    I had all of this info but can't put my hands on it now. Not something we use a lot.

    Thanks

  2. #2
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    Default

    I don't have figures with me as I'm on vacation but as I recall the 95 GPM portable eductors require 200 PSI at he intake side of the eductor to function properly. You maximum length would be reliant upon the capability and safety of providing that pressure to the eductor.

    Check the manufacturer's website. They may have it posted for download or an e-mail will probably get you all the info you need.

  3. #3
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    ** Your max is only the amount of PSI you have to use from your pump in order to get the proper pressure at the eductor.
    ** Now your max from the eductor to the nozzle depends on the hose size you are using:
    1 1/2...150ft
    1 3/4...200ft
    2 ...250ft
    **PSI to maintain is anywhere between 150 to 200 PSI with the "rule of thumb" being 200 PSI
    **At some point you wont get the concentrate of foam you need.. Check with your manufacturer for more detail..
    This is my opinion only and not of my department

  4. #4
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    you have to match the eductors with the nozzle, if you have a 95 gpm eductor, you need a 95 gpm nozzle. Depending on the nozzle most are 100 psi at the nozzle. The length of the hose should no more than 150ft and the eductor works best if it is at 100 ft from the nozzle. If you get more than 150ft from the eductor you will loss you foam concentrate and you won't make very good foam

  5. #5
    Junior Member

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    Apr 2000
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    Upper Canada
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    Default

    GPM

    Work the pressure requirements back from your nozzle given that you need 95 GPM flowing out the the business end. use the nozzle pressure for 95 GPM and subtract the friction loss and elevation loss for the length of hose from the eductor. Eductors use a venturi to suck the concentrate from the tank or container and introduce it into the water stream. The venturi requires a pressure drop (I think 25% - 35% depending on the make and model)across the hole to create the vacumn. Add the percentage drop to figure out what you need going into the eductor.

    Alternatively the rule-of-thumb is usually 200 p.s.i. into the eductor, so if we use 30% drop we have 140 p.s.i. out the other end. You should be able to calculate your hose length using the usual friction loss figures, the nozzle pressure for 95 GPM and the elevation difference.

    Of course the best method maybe to use calculations backed up with good solid field work and practice. Use several different set-ups and adjust pump pressure to get the best product. Keep track of the pump pressure, hose length, nozzle pressure and product charactoristics. Write it down and stick it on the eductor.

  6. #6
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    Default

    TO ANSWER YOUR QUESTIONS SPECIFICALLY...
    THE MAX DISTANCE FROM TRUCK TO EDUCTOR USING 1.5 INCH HOSE.
    REMEMBER THAT AT 95 GPM YOU HAVE AT LEAST 22 PSI FRICTION LOSS PER 100 FT OF 1.5 INCH HOSE. SO THE WAY TO GO IS TO SUPPLY THE EDUCTOR WITH 2.5 INCH
    THAT ONLY HAS 2 PSI OF FRICTION LOSS PER 100FT.
    THE DISTANCE FROM THE EDUCTOR TO NOZZLE WILL
    WILL BE 150 FT. USING 1.5 INCH HOSE
    USING 1.75 INCH WILL BE 300FT.

    ALL THESE LENGHTS AND FLOW RATES ARE BASED ON AN ELEVATION OF LESS THAN 10 FT.
    WHAT HAPPENS ABOVE 10 FT.? INCREASED FRICTION LOSS AND LESS WATER FLOW. THE FOAM CONCENTRATION WILL ACTUALLY INCREASE!!
    IF YOU SET THE EDUCTOR IS SET AT 3% IT WILL
    REALLY BE FLOWING A HIGHER CONCENTRATION DUE
    TO THE FACT THE SAME AMOUNT OF FOAM IS BEING
    DRAWN INTO THE EDUCTOR BUT LESS WATER IS COMING OUT THE NOZZLE.

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