Laboratory thermometers are specialized temperature-measuring instruments designed specifically for scientific and laboratory applications, capable of measuring temperatures ranging from -10°C to 110°C, which is much broader than clinical thermometers used for human body temperature.
Laboratory thermometers typically consist of a glass tube with a bulb at one end containing mercury or alcohol. The glass tube is marked with temperature scales in Celsius, Fahrenheit, or Kelvin units. These thermometers are made from strengthened glass through annealing or thermal tempering processes to withstand laboratory conditions. Unlike clinical thermometers, laboratory thermometers do not have kinks, allowing for continuous temperature readings as substances undergo temperature changes.
Liquid-in-Glass Thermometers
These are the most common type, featuring a glass bulb filled with temperature-sensitive liquids like mercury or red alcohol. Mercury expands as temperature rises and contracts as temperature decreases, providing accurate readings between -200°C and 600°C. Alcohol thermometers are considered safer since they don’t contain toxic mercury.
Infrared thermometers focus infrared energy onto a detector that converts it into temperature readings, ideal for measuring surface temperatures from a distance. Thermocouples use two different metal conductors with hot and cold junctions to measure extremely high temperatures up to 2300 K. Pyrometers detect surface temperatures based on radiation emitted from objects without making contact.
Laboratory thermometers serve multiple critical functions in scientific settings :
Laboratory thermometers offer several benefits over clinical thermometers. They can withstand extreme temperatures and harsh laboratory conditions without breaking or leaking. Their wider temperature range makes them suitable for measuring various substances beyond human body temperature. Many types, particularly liquid-in-glass thermometers, are inexpensive, easy to use, and require no power supply or batteries.
