Table 1 lists maximum service temperatures for long term exposures of bare wire thermocouples. For very short exposure times, temperatures of the fine gage thermocouples can be as high as the permissible temperatures for the 0.8 mm (0.032") diameter thermocouples.
** Do not expose to oxidizing atmospheres.
*The time constant is defined as the time required to reach 63.2% of an instantaneous temperature change. The data for Table 2 are obtained by measuring the time required for a Type J fine gage thermocouple to reach 63.2% of its final temperature when its junction is alternately exposed to two different temperature levels. In this case, the time constant was measured for exposures between 427°C (800°F) and 38°C (100°F) air between 93°C (200°F) and 38°C (100°F) water.