Volume 2, Issue 9 (October 2005)
Selection of Alternatives to Liquid-in-Glass Thermometers
A desire to increase automation or to eliminate the use of mercury has prompted several ASTM committees to consider alternatives to ASTM Liquid-in-Glass (LiG) thermometers. In this paper, we address the technical issues of choosing an alternative. We first discuss the basic properties and relative merits of platinum resistance thermometers, thermistors, and thermocouples in the context of replacements for LiG thermometers; then we list uncertainty components for measurements with alternative thermometers; and finally we discuss other factors in temperature measurement and control that are important in the development and execution of ASTM standards.