The Effect of Ambient Temperature on Infrared Thermometers

The accuracy of all electronic instruments is affected by the temperature of the environment in which they are being used. Large changes in the ambient temperature can introduce error in the readings of the device.

This is also true for infrared thermometers. When an IR thermometer is taken into a refrigerated space, the readings may be as much as 5 or 6 degrees off. The graph above shows what happens when we took four different IR thermometers from normal room temperature into a space that was 50ºF lower. If the IR thermometer is allowed to acclimate to the new temperature before being used, it will provide fairly accurate readings. We suggest the practice of placing the IR unit in the cooled space at least 20 minutes prior to taking readings.

However, if you don't have 20 or 30 minutes to wait, or you need to come and go from the cooled space frequently, then this changing ambient effect will introduce as much as 5 or 6 degrees of error. The new Cold Zone IR from ThermoWorks is designed to overcome this problem.

Most infrared thermometers are fitted with a lens to focus energy on the IR sensor. Many use a Fresnel lens made of plastic materials. These are particularly susceptible to thermal shock, as seen in the graph.

Some IR thermometers use a Mica lens. These are less susceptible to thermal shock but will still display an error of a few degrees.

The Cold Zone IR provides for maximum reading accuracy in a changing ambient temperature. We employ three strategies to accomplish this.

First, the Cold Zone IR is designed to be used only a few inches from the surface being measured so we eliminate the lens completely.

Secondly, the electronics feature a temperature compensation to minimize thermal drift in the components.

Thirdly, the Cold Zone IR uses our higher accuracy circuit option to provide the highest precision currently available over this temperature range.

If you need the other advantages of an IR thermometer with a lens (such as reading at greater distances from the object), then we suggest you adopt an SOP that ensures the IR thermometer will acclimate to a new environment before taking readings.

The alternative is to use our new Cold Zone IR. It fits your pocket or hangs from the neck lanyard. Come and go between cold and warm environments throughout the day and take temperatures on the fly with the ThermoWorks CZ-IR.