Precision Interchangeable Epoxy Thermistors YSI thermistors provide highly accurate and stable temperature sensing for applications of temperature measurement, control, indication and compensation. typical uses include precise measurements without the necessity of individual circuit calibration and with the advantage of precision interchangeability of sensors. Precise cold junction compensation of thermocouples may be designed directly without "bread boarding" after mathematically deriving the circuit because of the superior interchangeability of YSI precision thermistors. Two interchangeability tolerances and two thermistor configurations are offered. Teflon encased thermistors allow exposure to hostile environment such as conductive or corrosive liquids and particulate suspensions. A stiff wire placed in the tube also allows the thermistor leads to be formed to various shapes with slight finger pressure.
Time Constant: The time required for a thermistor to indicate 63% of a newly impressed temperature is the time constant. For a thermistor suspended by its leads in a well-stirred oil bath it is 1 sec. max. for standard thermistor and 2.5 sec. max. for teflon encased thermistors. In still air it is 10 sec. max. for standard thermistors and 25 sec. max. for Teflon encased thermistors. Dissipation Constant: The power in mW required to raise a thermistor 1°C above surrounding temperature is the dissipation constant.
For all thermistors suspended by their leads in a well stirred oil bath it is 8mW/°C min. or 1mW/°C in still air. Interchangeability: See Table = +/- 0.1°C Tolerance from 0 to 70°C = +/- 0.2°C Tolerance from 0 to 70°C Stability: YSI thermistors are chemically stable and not significantly affected by aging or exposure to strong nuclear radiation. The table shows typical thermoelectric drift. Operating: Typical Thermoelectric Drift Temperature 10 Months 100 Months 25°C <0.01°C <0.01°C 70°C <0.12°C <0.01°C 100°C <0.15°C <0.03°C 150°C <0.20°C <0.08°C 200°C <0.20°C <0.60°C