4-10. TYPES OF THERMOMETERS
a. Clinical. The clinical thermometer is a glass bulb containing mercury, with a
stem in which the mercury can rise. The stem has lines representing the measuring scale.
It must read below normal range before the temperature is taken. It should be rinsed in
cold water to avoid distribution of the mercury and breakage. If the thermometer is kept in
a chemical solution, dry it with a wipe in a twisting motion starting at the bulb. The clinical
thermometer may be oral or rectal.
(1) The oral thermometer has a long, slender bulb. It may also be used for
(2) The rectal thermometer has a blunt, short, fat bulb. It should not be stored
with the oral thermometers.
Figure 4-1. Clinical thermometers.
b. Electronic. The electronic thermometer is portable and battery operated. It
registers the temperature in 10 seconds or less and displays it digitally. It must be fully
charged to give an accurate reading, so be sure the thermometer's base is plugged into an
electrical outlet between uses. Separate oral and rectal probes are supplied with each
c. Disposable. The disposable is single-use and has a sensor at the end of the
shaft, which measures the temperature.
d. Patch. The thermometer patch is a strip, which contains liquid crystals that
change colors as the temperature changes. It is usually placed on the forehead. The
scale is adjusted to convert skin-surface temperature to inner-body temperature. The
calibration is not as detailed as that of a glass thermometer.