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Thread: ph versus scaling

  1. #1 ph versus scaling 
    3s
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    with a bit of lacking knowledge about chemistry I came across a problem caused by scaling in pipe works.After done some research on the net, i concluded scaling mainly consist of calcium/magnesium carbonates or calcium sulphates.Adding such chemicals to water with a Ph of 7, it will make the water ph rise (I assume).
    raising the temperature of the water will increase the sollubility (I assume).
    so here is the question:
    is there some data available to state:
    At this temperature, the ph of water can be maximum ..., without risking the formation of scaling.
    or with this ph the water temperature should be minimum...,without risking the formation of scaling.
    or a ph versus temperature plot, giving the boundary conditions for not risking the formation of scaling


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  3. #2 Re: ph versus scaling 
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    [quote="3s"]with a bit of lacking knowledge about chemistry I came across a problem caused by scaling in pipe works.After done some research on the net, i concluded scaling mainly consist of calcium/magnesium carbonates or calcium sulphates.Adding such chemicals to water with a Ph of 7, it will make the water ph rise (I assume).[/qoute]

    Yes slightly because CO4+ H2O <-> HCO4 +OH- <-> CO2 + OH-

    (not balanced)

    raising the temperature of the water will increase the sollubility (I assume).
    No, incorrect in the case of CaCO4 and MgCO4 higher temperature and in addition lower pressure induces scaling.

    so here is the question:
    is there some data available to state:
    At this temperature, the ph of water can be maximum ..., without risking the formation of scaling.
    Are you asking by altering pH can you prevent scaling of a saturated solution at constant temperature? If so, yes but only to a very slight degree. A far more effective strategy is to remove the Ca and Mg using a water softener or tie them up with a chelating agent.

    or with this ph the water temperature should be minimum...,without risking the formation of scaling.
    Yes lowing temperature is an effective method at preventing scaling of a saturated solution of Ca and Mg ions.

    or a ph versus temperature plot, giving the boundary conditions for not risking the formation of scaling
    Yes that is effective.


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  4. #3  
    3s
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    let me rephrase that:
    can one predict weather the formation of scaling will occure or not by measuring ph and temperature of the water?
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  5. #4  
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    Yes, if you also know the concentration or know that it is saturated, and you know the pressure since scaling is a function of pressure too.
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  6. #5  
    3s
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    thanks for the reply
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