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Thread: Bullk Reation Coefficient

  1. #1
    Associate Engineer
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    Bullk Reation Coefficient

    Is there an industry standard for a bulk reaction coefficient when beginning a design. I am connecting a pipe to an existing distribution system. I know the initial Cl- content. I am trying to juggle fire flow and quality. I am using EPAnet to water the system. Is there an acceptable value to use for the reaction coefficient or is the only option to perform a jar test on a sample of the water? I find it hard to believe that there are no good resources on this in the vast spaces of the internet.

    EPAnet says to use -1 but I assume this is a general value. I also assume that since fire flow usually dictates pipe size that modeling quality is not really a top priority and is simply dealt with after the fact. This may be why there is not a lot of info out there regarding this coefficient.

    Thanks in advance.

  2. #2
    Administrator Kelly Bramble's Avatar
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    I was unable to find a definition for "Bulk Reaction Coefficient" while searching the internet.

    Is this a EPANET unique phrase or term? How does EPANET use the coefficient in their calculations?

  3. #3
    Lead Engineer Cake of Doom's Avatar
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    Did you mean the bulk reaction rate coefficient, as in, kb (1/T)?

  4. #4
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    Quote Originally Posted by Cake of Doom View Post
    Did you mean the bulk reaction rate coefficient, as in, kb (1/T)?

    Yes that is the correct coefficient. the Decay rate of chlorine in the water. I know how to find it by measuring the chlorine content at time intervals and then graphing the log and taking the slope of the line of best fit as the coefficient, assuming it is linear which is valid assumption for chlorine. However, I don't have the equipment or time to do this and I can't imagine that this is performed every time an engineer performs a hydraulic model. But maybe it is. I realize this is specific to each water source so it may be determined experimentally every time but I just assumed there must be a generic starting value or range that is used when first starting a project to see if it is even feasible.

    Thank you both for your responses.

  5. #5
    Lead Engineer Cake of Doom's Avatar
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    Just for a feasibility study I usually go and see if I can find a previous project that is similar to one I've been asked to do. This should at least provide you with some basic starting values if non can be found in the EPANET toolkit.

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