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Temperature responsive indicators for process control instruments

  • US 7,528,737 B2
  • Filed: 04/10/2006
  • Issued: 05/05/2009
  • Est. Priority Date: 04/10/2006
  • Status: Active Grant
First Claim
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1. A process transmitter comprising:

  • a housing;

    a sensor within the housing for producing a sensor signal as a function of a process variable;

    transmitter circuitry within the housing for producing a variable electrical output based on the sensor signal and communicating the variable electrical output over a process control loop; and

    a temperature responsive indicator visible from an exterior of the housing, the indicator being visually responsive to a temperature change of the indicator induced by resistance heating of a conductive ink generated by the variable electrical output of the transmitter circuitry before being communicated over the control loop.

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