Laboratory thermometers are used to measure temperatures or temperature changes with a high degree of precision. They are made of metal or glass and strengthened through thermal tempering or annealing.
The way a laboratory thermometer works depends upon its type. They are generally a liquid-in-glass device, a bimetallic strip, an electronic thermistor thermometer, or infrared (IR) device.
Specifications
The Engineering360 SpecSearch database allows industrial buyers to select laboratory thermometers by type, display options, operating environment, and specialty features.
Types
Several types of laboratory thermometers are commonly available including:Liquid-in-glass
Liquid-in-glass thermometers are made of sealed glass and contain a fluid, usually mercury or red alcohol, whose volume changes relative to its temperature. The liquid expands as the temperature rises, rising in the tube and indicating the temperature. When choosing a liquid or gas-filled thermometer, there are several things to consider, including: Material in tube - gas or liquid; Material of tube - glass or metal; Level of liquid or gas in the tube.
Bimetallic Strip
Bimetallic strip thermometers include two different metals that are bonded together and expand at different rates as they warm up. Since the two metals expand to different lengths, the bimetallic strip is forced to bend or curl towards the side with a lower coefficient of thermal expansion. The movement of the strip is used to deflect a pointer over a calibrated scale which then indicate temperature to the user. Often, long bimetallic strips are wound into a coil and used with a dial.
Advantages include: Low cost, tough, easy to use and install, accurate over a wide range of temperatures
Disadvantages include: only indicating types are available, possibility of calibration change due to use or environment, and not as accurate as glass stem thermometers.
Electronic Devices
Electronic devices such as thermistors measure changes in electrical resistance and convert them to changes in temperature.
Infrared Thermometers
Infrared thermometers are non-contact devices that convert infrared (IR) energy to an electrical signal that can be displayed in units of temperature.