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Why use noncontact infrared
thermometers?
Noncontact
infrared (IR) thermometers use infrared technology to quickly
and conveniently measure the surface temperature of objects.
They provide fast
temperature readings without physically touching the object.
You simply aim, pull the trigger and read the
temperature on the LCD display.
Lightweight, compact, and easy-to-use, IR thermometers can
safely measure hot, hazardous, or hard-to-reach surfaces
without contaminating or damaging the object. Also, infrared
thermometers can provide several readings per sec ond,
as compared to contact methods where each measurement can take
several minutes.
How does IR work?
IR
thermometers capture the invisible infrared energy naturally
emitted from all
objects.
Infrared radiation is part of the electromagnetic spectrum
which
includes
radio waves, microwaves, visible light, ultraviolet, gamma,
and X-rays.
About Emissivity
 This
infrared "invisible heat" of an object is transferred in three
ways: Reflected, Transmitted, and Emitted. Reflected energy is
not particularly related to the temperature of the target
object, and transmitted heat is related to the both the
internal temperature of the target object and the temperature
of the "transmitted to" object.
The only
type of energy that can be used to tell that actual surface
temperature of the object is Emitted energy.
When IR
thermometers are used to measure surface temperature they can
potentially sense all three kinds of energy, therefore all
thermometers have to be adjusted to read Emitted energy only.
Measuring errors are often caused by IR energy being reflected
by light sources.
Some IR
thermometers allow you to change the emissivity in the unit.
The value of emissivity for various materials can be looked up
in published emissivity table.
Other
units have a fixed, pre-set emissivity of 0.95, which is the
emissivity value for most organic materials and painted or
oxidized surfaces. If you are using a thermometer with a fixed
emissivity to measure the surface temperature of a shiny
object you can compensate by covering the surface to be
measured with masking tape or flat black paint. Allow time for
the tape or paint to reach the same temperature as the
material underneath. Measure the temperature of the taped or
painted surface. That is the true temperature.
Accurate Temperature
Measurement Tips
When
measuring shiny surfaces, such as aluminum and stainless
steel, the reflectivity of the surface will skew the reading
of an IR thermometer unless you accommodate for it. Either
coat surfaces such as griddles or cooking pans with a
non-stick cooking spray before you take your reading, or place
a small piece of masking tape on the metal surface and measure
the taped area.
An IR
thermometer can go from kitchen to cold storage (above
freezing) and still provide an accurate reading if given time
to acclimate to the new ambient temperature. It's best to
leave the unit where it will be used most often. Note: If the
unit is left in an environment below freezing, it will
temporarily fail to operate properly.
Use an IR
thermometer to read internal temperatures of liquids, such as
soups or sauces, simply by stirring the liquid and then
reading the surface temperature. Keep the thermometer away
from steam to avoid condensation on the lens, which will skew
your reading.
Factors That Affect the Accuracy of
Readings
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1) Field-of-view.
Make sure that the target is larger than the spot size the
unit is measuring. The smaller the target, the closer you
should be to it. When accuracy is critical make sure that
the target is at least twice as large as the spot size.
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2) Distance to spot ratio.
The optical system of an infrared thermometer collects the
infrared energy from a circular measurement spot and
focuses it on the detector. Optical resolution is defined
by the ratio of the distance from instrument to the object
compared to the size of the spot being measured (D:S
ratio).
The larger the ratio number the better the instrument's
resolution, and the smaller the the spot size that can be
measured. The laser sighting included in some instruments
only helps to aim at the measured spot.
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Monitoring Food
 Receiving.
Quality assurance begins at the receiving dock. When a
delivery of fresh or frozen food arrives, use your Global
Sensors IR thermometer to check that the products, shipping
crates, and internal temperature of the delivery truck are all
at the right temperatures.
Storage.
Once received, verify that frozen and chilled foods are stored
at or below 40°F (4.4°C) to assure freshness and quality. In
supermarkets where product may be stacked unevenly or too high
in display cases and freezers, check to find warm spots or
uneven cooling. Also, you can quickly and frequently monitor
proper temperatures of all items stored in walk-ins.
Cooking.
Exact temperatures become vital to preventing food-borne
illness. To avoid bacteria growth, many foods must be cooked
to a specific temperature. An All QA Products thermometer
instantly confirms that your surface temperatures are within
safe parameters. In order to confirm internal temperatures,
you can use All QA Products thermometer that feature an
internal probe.
Holding
and Serving. Food products that are ready to be served or
sold and are located in holding or serving areas must be kept
out of the Temperature Danger Zone which is 40 to 140°F or 4.4
to 60°C.
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Cold Holding
With your IR thermometer, quickly verify that the
temperature of products held in open-top refrigeration
units, such as fresh meat or fish displays, cold buffets, or
preparation units, do not exceed 40°F (4.4°C), as mandated
by the FDA's 2000 Food Code.
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Hot Holding
Warm prepared foods that are kept in steam tables, warming
ovens,
and other heated serving and holding areas should be
carefully monitored to
remain at 140°F (60°C) or above. You can use your IR
thermometer to check the
internal temperatures of soups, gravies, and other liquid
foods by agitating them
before reading.
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Cooling
Improper cooling is the number one cause of food borne
illness. After food has been cooked and served, use your All
QA Products thermometer to confirm that leftovers are taken
down to an appropriate temperature—from above 140 to below
70°F (60 to 21.1°C) within two hours, and then down to below
40°F (4.4°C) within another four hours.
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Reheating
The last important temperature-related checkpoint is
reheating. Your IR thermometer can confirm that foods are
being reheated to at least 165°F (73.9°C) to destroy any
bacteria caused by improper cooling or storage techniques.
Monitoring Equipment
You can
use your noncontact thermometer to check more than just the
temperature of food. You can also evaluate the performance of
your equipment and machinery.
Detect
hot spots or leaks by taking sample spot readings of
freezers, walk-in coolers, refrigeration lines, compressor
motors, electrical, and HVAC equipment.
Safely
check the temperature and performance of ovens, ranges,
rotisseries, deep
fryers and dishwashers.
Check
clean dishes immediately after washing to ensure that high
enough
temperature levels were achieved in the dishwasher for
sanitation purposes.
Other
Uses in Gourmet/Specialty Cooking
Many specialty food recipes call for very specific preparation
temperatures. For example, sugar used in meringues and icings
relaxes to the softball stage at 220°F (104°C); at 320°F
(160°C) caramel reaches the stage for flavoring and
decorating, and at 350°F (177°C) it darkens. By using an IR
thermometer you can instantly check these temperatures and
avoid the mess of using a contact thermometer.
Experience
notwithstanding, it is often difficult to know when cooking
surfaces have reached the proper temperatures. For example, a
common way to test whether a griddle is "pancake ready" is to
see if a drop of water skittles across its surface. But water
does this at a wide temperature range—roughly between 320° to
440°F (160° to 227°C)—whereas pancakes griddle best between
350° and 370°F (177° and 188°C) and meat, on the other hand,
sears best at about 450°F (232°C). By instantly knowing these
temperatures you can avoid the guesswork and ensure food is
cooked perfectly.
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