(! !& " & PRACTICE
•IR thermometers work best at ambient temperature. They will not function prop- erly if they are subject to an abrupt tem- perature change. If the IR thermometer has a temperature dierence of ≥70 °F (~20 °C) to the ambient environment, such as in a refrigeration or freezer unit, wait 15 to 20 minutes before taking the reading. Like- wise, when working in a warm kitchen and before taking temperature measurements in a walk-in refrigerator, “condition” the thermometer by placing it on the counter or in the refrigerator for 15 to 20 minutes before taking any readings. To avoid tem- perature extremes between clients, carry the unit in an insulated tote and preferably in a protective case to prevent damage to sensors and electronics. •Keep the unit away from exposure to electromagnetic and electrostatic noise, such as wireless communications devices. These sources could result in inaccurate measurements. • For the most accurate measurements, aim IR thermometers perpendicular to the tar-
get. If possible, the field of view should be an even, horizontal plane—in other words, a flat surface. •Response time varies with each instru- ment. Always refer to the instruction man- ual for response time specifications. • Air temperature cannot be measured with an IR thermometer. Only the temperatures of a solid object can be measured. Ambient temperature can be estimated, however, by aiming the device at an object within the area that is in equilibrium with its ambient air temperature. The temperatures should be the same. •Our IR thermometers cannot be cali- brated. They can, however, be validated and should be validated regularly (suggest weekly or more often) in much the same way as measuring ambient temperature. The procedure is simple. Ax a black spot or nonreflective masking tape to a file cabi- net or other piece of furniture. Avoid plac- ing the spot or tape where it can be aected by radiant heat. When the spot or tape has come to equilibrium, a temperature mea-
surement can be taken. By comparing the reading of the IR thermometer to a temper- ature-standard thermometer (in water) at equilibrium, the accuracy can be validated. We use a hot/cold validation for our IR, by using a black spot on an aluminum can, in much the same way that we calibrate or validate our thermocouple, thermistor, and bimetal thermometers. And always remem- ber to record your validation results. • Change the battery of the IR thermometer regularly and well before the end of its life. Some units show fewer problems, particu- larly with thermal shock, when a fresh battery is in place. None of the IR ther- mometers we consistently use work well in subfreezing temperatures, regardless of thermal conditioning or battery strength. So, there you have it. A brief review of the use and care of IR thermometers. And as a gentle reminder, we welcome any comments and anecdotes you might have regarding this column. We look forward to seeing them.
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