Typical Applications
by Vern Lappe, Ircon/Raytek Corp.
April 1, 2009
In this web-exclusive sidebar to his feature article, Vern Lappe of Ircon/Raytek looks at applications well suited for infrared temperature measurement.
Infrared thermometers can be used in food cooling
applications ranging from candy manufacturing to ensuring the right temperature
of frozen peas and baked goods.
For manufacturing candy bars, the chocolate is poured into
plastic molds. These molds are a thick plastic and are chilled to a temperature
of 62°F (17°C) before they are filled with chocolate. If the molds are not
sufficiently cooled, then the bars will not be solid enough to be wrapped.
Conversely, pouring the chocolate into molds that are too cool can alter the
color of the chocolate and make it visually unappealing to the consumer. The
temperature of the molds is easy to control with infrared devices because the
target is large and the temperature is measured at the exit of the cooler. The
color of the molds will not affect the measurement or the emissivity setting
required on an infrared thermometer.
Many candy-making processes require sugar or corn syrup to be
melted and later cooled to a taffy-like condition. To obtain the proper process
temperature, the sugar or corn syrup is poured over chilled rolls. The tendency
is to control the roll temperature using contact-type temperature measurement
devices to measure the sugar temperature is not practical because sugar buildup
would insulate the sensor and result in an inaccurate temperature indication. Infrared
sensors can provide improved measurement accuracies in this application. Again,
the color and thickness of the sugar or syrup do not influence the thermometer
setting.
Frozen food is a big market for the use of infrared
thermometers. Products such as frozen corn, peas, French fries and waffles must
be cooled rapidly to the right temperature to prevent color changes that would
make them unappealing to consumers. They are typically flash-cooled to
approximately -36°F (-38°C). In these applications, the infrared instruments
are installed so that they measure the food temperature as the food exits the
flash-cooling chamber. The instrument is not installed to measure the food in
the actual cooling chamber because moisture in the air will interfere with the
temperature indication.
In
the highly automated production of baked goods such as pizza, accurate
temperature measurement is crucial to ensuring process safety. If a baked food
product is not properly cooled before it is packaged, it can start a fire that
could destroy the process line or, worse yet, cause major damage to the entire
factory or warehouse. Infrared thermometers can monitor the temperature of the
product to ensure that it is cooled to specification.
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