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View Diary: BP Top Kill Diary # 7 as of 10 pm MDT appx (374 comments)

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  •  A thermocouple might tell flow rate (3+ / 0-)
    Recommended by:
    greenearth, jwinIL14, Onomastic

    by measuring the change in resistance or temperature differential across the couple.

    I have seen something similar used to measure sap flow rate in a tree (a much slower process!), but I suppose that the concept would work in a similar way for this situation.

    A Wall Street "bonus" should not be more than what my house is currently worth.

    by bushondrugs on Thu May 27, 2010 at 11:40:28 PM PDT

    [ Parent ]

    •  Fascinating and somehow poetic too. (2+ / 0-)
      Recommended by:
      abarefootboy, bushondrugs

      I suppose you'll just have to trust me on that, or not.

      Stepping up to life eliminates the capacity for bullshit. - Robinswing

      by Onomastic on Thu May 27, 2010 at 11:48:26 PM PDT

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    •  At those depths and pressures an RTD makes (0+ / 0-)

      great deal of sense vs. a thermistor or a thermocouple.

      " It's shocking what Republicans will do to avoid being the 2012 presidential nominee."

      by jwinIL14 on Fri May 28, 2010 at 12:11:31 AM PDT

      [ Parent ]

      •  RTD/thermocouple (0+ / 0-)

        Thermocouples are available with 40,000PSI design pressures (60,000 PSI proof pressures).  

        I would suspect that an RTD might get confused about whether it is measuring temperature or pressure (pressure sensitive resistor or strain gage effects) but I did see at least one enclosed probe that was rated to 30,000PSI (proof).   The higher accuracy of an RTD would probably be unneeded and unrealized under such conditions.  From a brief glance it looked like two wires were used which would be more appropriate for a thermocouple than an RTD.    

        GP mentions using a thermocouple as a flow sensor.   That would likely depend on knowing the composition of the liquid, or at least its thermal properties.  Hard when you are measuring an unknown mix of oil fractions, methane, mud, sea water, etc.   Turbulence compounds the problem.

        One general problem with sensors is that they usually measure (are sensitive to) more than one parameter so adverse environmental conditions can result in errors.

        There are all kinds of sensors out there.    The oil drilling industry probably has some neat ones.

        The floppy wires would be even more of a problem if you were trying to measure flow or pressure vs temperature.

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