Resistive thermal detectors

For most points requiring temperature monitoring, either thermocouples or resistive thermal detectors (RTD s) can be used. Each type of temperature transducer has its own advantages and disadvantages, and both should be considered when temperature is to be measured. Since there is considerable confusion in this area, a short discussion of the two types of transducers is necessaiy. 

Resistive Thermal Detectors (RTDs) RTDs determine temperature by measuring the change in resistance of an element due to temperature. Platinum is generally utilized in RTDs because it remains mechanically and electrically stable, resists contaminations, and can be highly refined. The useful range of platinum RTDs is... 

While redundancy—backing up one system with another just like it—is a logical way to protect against instrument failure, diversity may be a better choice in many cases. For example, dual thermocouples in the same well could corrode out at the same time. It might be better to have two different types of measurement, one a thermocouple in a thermowell and the other possibly a resistance thermal detector. 

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