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| January
8, 2008 Sponsored
by:
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Make a New Year’s
Resolution for Safety
Tip written by:
Infraspection Institute
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With the New Year upon us,
many of us will follow the tradition of resolving to change
or better ourselves. With this Tip, we offer suggestions for
making job safety a priority.
The New Year is symbolic for many reasons.
For some, the New Year represents a fresh start or new beginning.
For others, it provides an opportunity to rededicate one’s
self to a set of goals or principles. The New Year provides
a perfect opportunity for thermographers to take stock of
workplace safety practices and procedures. In doing so, be
sure to keep the following in mind:
• Review safety procedures to ensure
that they are complete and current
• Ensure that safety training is
up-to-date for all personnel including First Aid and CPR
• Physically inspect all Personal
Protective Equipment to ensure it is in good condition
• Check calibration and/or replacement
dates for all monitoring or test equipment
Lastly, resolve to make safety your number
one priority each and every day. Safety is not a poster, a
slogan, or a set of actions to be followed only when it is
convenient. Rather, safety is way of life that affects not
only you but those around you.
Thermographer safety is one of the
many topics covered in the Level I Infraspection Institute
Certified Infrared Thermographer® training course. For
information on thermographer training including course locations
and dates, visit us online at www.infraspection.com or call
us at 609-239-4788.
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Infraspection Institute Web Site
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| January
14, 2008 Sponsored
by:
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Inspecting Shaded
Building Elevations
Tip written by:
Infraspection Institute
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Infrared inspections of building
exteriors often rely on solar loading to create temperature
differentials necessary to detect damage or defects. A common
challenge for thermographers is inspecting building elevations
that do not receive direct sunlight.
Infrared imaging is a proven technique for
testing building sidewalls. Inspecting buildings during evening
hours following a sunny day can reveal the presence of structural
details, missing or damaged insulation, or latent moisture.
These conditions are detectable due to changes in the thermal
capacitance or conductance of the walls.
When using solar energy to drive an infrared
inspection of building sidewalls, it is normal for a building
to heat unevenly. Typically, east elevations receive the least
direct sunlight, while the south and west elevations receive
the most. For many northern latitudes, north elevations do
not receive direct sunlight.
Fortunately, it is not necessary to receive
direct sunlight in order to drive an infrared inspection.
Provided that the building is not in close proximity to other
structures or heavily shaded areas, it will receive indirect
heating from nearby objects such as the ground. For elevations
that are heated indirectly, it is important to note that they
will exhibit weaker thermal patterns when compared to other
exposures that receive direct sunlight.
When using solar loading to drive an infrared inspection,
keep the following in mind:
• Choose an evening when weather
conditions are optimal - sunny day followed by a cool clear
evening with no wind
• Begin infrared inspection on the
North elevation and continue in a clockwise fashion around
the exterior of the building
• Depending upon wall construction,
type of defect, and local weather conditions, it may be
necessary to begin prior to sunset
Lastly, be aware that thermal patterns associated
with defects may only appear for a short period of time on
the North and East elevations. All thermal anomalies should
be investigated for cause and appropriate action taken.
Infrared inspection of building envelopes
is one of the many topics covered in the Level I Infraspection
Institute Certified Infrared Thermographer® training course.
For information on thermographer training including course
locations and dates, visit us online at www.infraspection.com
or call us at 609-239-4788.
Visit
Infraspection Institute Web Site
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| January
21, 2008 Sponsored
by:
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Thermal Imager Rental
–
A Smart Alternative
Tip written by:
Infraspection Institute
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With prices ranging to over
$30,000, a thermal imager can represent a considerable investment.
For companies getting started in thermal imaging, renting
an imager can provide a cost effective alternative to purchasing
a system outright.
Whether you are facing an equipment shortage
or looking to evaluate the characteristics of a new imager
prior to purchase, renting a thermal imager may provide a
solution. In some cases, imager manufacturers will credit
short term rental fees toward the purchase price of an imager.
As with purchasing an imager, there are several important
things to consider when arranging for a rental unit.
To help ensure that you select an appropriate
imager for rental, be certain to:
• Identify appropriate spectral response
required for project
• Determine if temperature measurement
is required
• Evaluate the system for objective
specifications
• Ascertain imager compatibility
with reporting software
When arranging for a rental, obtain terms
and conditions from the rental agency. These should include,
but not be limited to: rental period, extension of rental,
shipping costs, and requirements for insurance against loss.
One should also consider the rental agency’s ability
to provide technical support during the rental period.
For more information on choosing an infrared
imager, refer to the article, “Selecting,
Specifying, and Purchasing a Thermal Imager” available
as a free download on this website.
Lastly, the greatest limiting factor
in any infrared inspection is the thermographer. For accurate
results, infrared inspections should only be performed by
properly trained and certified thermographers. For more information
on thermographer training and certification, please contact
Infraspection
Institute.
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Infraspection Institute Web Site
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| January
28, 2008 Sponsored
by:
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Frostbite & Hypothermia
Tip written by:
Infraspection Institute
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“Jack Frost nipping
at your nose.” These lyrics from a popular Christmas
carol evoke romantic visions of winter; however, frostbite
and hypothermia are dangerous medical conditions that can
present serious safety hazards.
For many, the dead of winter is upon us.
Thermographers working outdoors in cold climates can face
serious safety challenges due to frostbite and hypothermia.
Knowing the symptoms of these conditions and proper treatment
is imperative for worker safety.
Frostbite is a severe reaction to cold exposure
that can permanently damage its victims. A loss of feeling
and a white or pale appearance in fingers, toes, or nose and
ear lobes are symptoms of frostbite.
Hypothermia is a condition brought on when
the body temperature drops to less than 90 degrees Fahrenheit.
Symptoms of hypothermia include uncontrollable shivering,
slow speech, memory lapses, frequent stumbling, drowsiness,
and exhaustion.
If frostbite or hypothermia is suspected,
begin warming the person slowly and seek immediate medical
assistance. Warm the person's trunk first. Use your own body
heat to help. Arms and legs should be warmed last because
stimulation of the limbs can drive cold blood toward the heart
and lead to heart failure. If the person is wet, put them
in dry clothing and wrap their entire body in a blanket.
Never give a frostbite or hypothermia victim
beverages containing caffeine or alcohol. Caffeine, a stimulant,
can cause the heart to beat faster and hasten the effects
the cold has on the body. Alcohol, a depressant, can slow
the heart and also hasten the ill effects of cold body temperatures.
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Infraspection Institute Web Site |
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| January
4, 2008 Sponsored
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Cold Weather Clothing
Tip written by:
Infraspection Institute
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Last week’s tip discussed
the dangers of Frostbite and Hypothermia while working in
cold temperatures. This week’s tip covers cold weather
clothing.
Cold weather clothing is a matter of functionality
not fashion. Clothing needs to be worn in layers in order
to trap air which is warmed by the body. When selecting clothing,
start with the innermost layer and work outward. The use of
multiple layers will trap warm air while providing greater
ease of movement. As you add layers, be sure to adjust the
next layer’s size accordingly.
The first layer should be made of a synthetic
material that will wick perspiration away from the body and
maintain its insulating properties when damp. The second layer
is your main insulator and should be a breathable material
that maintains its insulating properties when wet. Synthetic
fleeces or natural wool are good choices. The outermost layer
should be breathable and both wind and water resistant.
Head and neck protection is a must since
nearly 40% of body heat is lost here. Perspiration is the
main enemy of feet. The best footwear will have sturdy outers,
good treads and a removable felt liner. Buy extra liners and
replace them every few hours. Liners can take a full day to
fully dry out so buy enough to get through a typical workday.
Mittens are the warmest but present problems
in grasping tools etc. I have found that a heavy duty welder’s
glove with cotton or wool gloves lining them provide good
warmth and mobility. Buy enough liners to get you through
the day. One final note, the body needs fuel to produce heat.
Your calorie needs increase in cold weather and require regular
replenishment with good wholesome foods.
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Infraspection Institute Web Site
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| January
11, 2008 Sponsored
by:
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Infrared Inspections of Lightning Arrestors
Tip written by:
Infraspection Institute
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Infrared thermography is
a proven technology for detecting defects in electrical circuits
that are under load. Thermal imaging can also be used to detect
defective lightning arrestors that are leaking current to
ground.
Lightning arrestors are a common feature
in electrical distribution systems and are used to guard against
voltage surges associated with lightning strikes on power
or communications lines. Installed at strategic locations,
lightning arrestors act like a safety valves to provide a
short circuit path that carries excess voltage to ground during
a lightning strike.
Lightning arrestors are connected between
a conductor and ground. In order to prevent a ground fault,
lightning arrestors are engineered so that normal line voltage
will not pass through the arrestor under normal conditions.
While some lightning arrestors employ a simple spark gap,
others consist of porcelain tubes that are filled with semi-conductive
discs made of silicon carbide or zinc oxide. During a lightning
strike, the resistance of the spark gap or oxide plates is
overcome and excess energy flows to ground.
If a lightning strike is sufficiently strong,
lightning arrestors may be permanently damaged and begin to
conduct electricity to ground full time. When this happens,
the body of the arrestors will heat up allowing them to be
detected with a thermal imager. The images below show two
examples of defective arrestors.
Infrared inspections of lightning arrestors
are primarily qualitative in nature. As such, thermographers
should compare similar arrestors to one another and note any
that are inexplicably warm.
Properly functioning lightning arrestors
should be uniform in temperature and close to ambient air
temperature if they have not undergone recent solar loading.
Individual arrestors should not have any pronounced hot spots
across them. Working early in the morning, on cloudy days
or at night will help to eliminate solar loading which can
hide defective arrestors. When performing your inspection,
don't forget to check grounding connections for hot spots
as well.
Infrared inspection of power distribution
systems is one of the many topics covered in the Level I Infraspection
Institute Certified Infrared Thermographer® training course.
For information on thermographer training including course
locations and dates, visit us online at www.infraspection.com
or call us at 609-239-4788.
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Infraspection Institute Web Site
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| January
18, 2008 Sponsored
by:
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Infrared Inspections of Spandrel Glass
Panels
Tip written by:
Infraspection Institute
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Thermal imaging is widely
used to detect evidence of excess energy loss in building
envelopes. Under proper conditions thermal imaging may be
used to detect excess energy loss through spandrel glass panels.
Glass curtain walls are a common feature
found on modern commercial buildings. Opaque glass panels
called spandrels are used to cover materials or prevent construction
elements from being viewed from the exterior of the building.
Examples of such areas include areas between floors, hung
ceiling areas, knee-wall areas below vision lights, and sometimes
even columns or partitions.
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Spandrel
panels appear as dark horizontal bands on this high
rise building. |
Depending upon building construction, spandrel
glass may be installed as single-thickness panes, as part
of insulating glass units, or as laminated glass. When installed
as single pane units, spandrel panels are often insulated
to prevent excess energy loss; however, construction details
will vary between systems.
When performing an infrared inspection of
spandrel glass panels, keep the following in mind:
• Prior to the infrared inspection,
ascertain building usage and construction. Be aware of HVAC
settings and how they are likely to affect observed imagery.
• Spandrel glass panels can vary
widely. Determine panel construction and characteristics
prior to the inspection.
• When imaging from a building’s
exterior, significant errors can be introduced by hot/cold
reflections from nearby structures or the sky.
• Because spandrel glass often has
a low emittance; detected exceptions are likely to have
low temperature differentials.
Infrared inspections of spandrel glass should
be performed during evening hours with an inside/outside temperature
differential of at least 10ºC. Exceptions associated
with spandrel glass may appear as hot or cold depending upon
building usage, imaging vantage point, and panel construction.
As always, detected exceptions should be investigated for
cause and appropriate corrective measures taken.
Infrared inspection of building envelopes
is one of the many topics covered in the Level I Infraspection
Institute Certified Infrared Thermographer® training course.
For information on thermographer training including course
locations and dates, visit us online at Infraspection
Institute or call us at 609-239-4788.
~ Tip suggested
by Kevin Richardson,
ITI Network
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Infraspection Institute Web Site
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| February
25, 2008 Sponsored
by:
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Negative Findings Versus
No Problems
Tip written by:
Infraspection Institute
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When documenting an infrared
inspection with no detectable exceptions, thermographers should
be aware that there is a big difference between reporting
“no problems” versus “negative findings”.
Infrared inspections may be performed for
a wide variety of reasons including condition assessment,
quality assurance and predictive maintenance. In its simplest
form, thermography detects, displays and records thermal images
and temperatures across the surface of an object. In many
cases, thermal anomalies are indicative of deficiencies, changes,
or undesirable conditions within the object or system being
inspected. Typically, such conditions are reported with a
thermal image and a description of the anomaly.
Upon completing infrared inspections during
which no anomalies are detected, thermographers will frequently
report that the subject system has “no problems”.
From a liability standpoint, this can increase a thermographer’s
risk since there may exist problems that are simply not detectable
by thermography. Most importantly, a proclamation of “no
problems” may leave an end user with a false sense of
security regarding the condition or integrity of the subject
system.
Since it is not possible for thermography
to detect all potential problems within a given system or
object, it is advisable for a thermographer to report “negative
findings” when no anomalies are detected. This statement
is direct, to the point, and in accordance with terminology
utilized in other types of scientific testing.
Although the difference between “no
problems” and “negative findings” may seem
small, the proper use of terminology can help to prevent costly
and embarrassing misunderstandings.
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Infraspection Institute Web Site
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| March
3, 2008 Sponsored
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Infrared inspections
of electrical systems can help to improve the efficiency of
a preventive maintenance program. In this Tip, we focus on
several key considerations for setting up inspection routes.
Electrical infrared inspections
are best performed when carefully designed routes are set
up listing the equipment to be inspected. But how does one
go about designating a route? To answer this, you must first
understand your electrical system layout. Keep in mind that
electrical systems are designed to fit the type of operation
of a facility. In general, in-plant electrical systems begin
with higher voltage classes nearest the incoming source of
electricity and branch down to lower voltage classes via transformers
to meet specific power demands throughout the facility.
As a general guideline, the
following is a list of the types of electrical systems found
at various facilities:
Industrial / Large Manufacturing
- 23 to 13kV supply voltage on site that
is stepped-down to 4160V and 277/480V for various motor
and lighting loads (substations, load interrupter switches
and large transformers are common with this set-up)
- 277/480V is stepped-down to 120/208V
via transformers for receptacle, computer, and lighting
loads
Medium to Small Manufacturing / Large
Commercial / Healthcare
- 277/480V supply voltage is brought into
the facility via outside pad-mount or pole-mounted transformers
to be used for various motor and lighting loads and stepped-down
to 120/208V via transformers for receptacle, computer, and
lighting loads
Small Commercial / Office
- 120/208V or 110/240V supply voltage brought
into the facility via outside pad-mount or pole-mounted
transformers used for receptacle, computer, and lighting
loads
Infrared inspection routes can set up based
upon various criteria including but not limited to, specific
areas or operations in your facility, by voltage class of
equipment, by individual circuit branches, by criticality
to operation of a facility, or other determining factors deemed
important.
Keep in mind that routes should be limited
to the amount of equipment that can inspected in a single
day or shift. Routes should also start with high-voltage equipment
closest to the incoming power source as failures high in the
electrical hierarchy generally affect larger portions of the
facility than lower voltage equipment.
~ Tip provided
by Brady
Infrared Inspections, Inc.
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| March
10, 2008 Sponsored
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How Dust Creates Full Size Thermal
Imagery
Tip
written by: Infraspection Institute
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When performing an infrared
inspection of the interior of a building, you may be able
to visually observe full-size thermal images without your
thermal imager. The cause of this phenomenon is simple dust
and dirt normally found within most buildings.
Many buildings employ cavity wall details
in the construction of interior spaces. When the exterior
of framed walls are exposed to cold temperatures, areas with
diminished R values will cause the interior surfaces of the
wall to cool. Such cold areas may be caused by framing members
or wall cavities with missing or damaged insulation.
If interior humidity levels are high and
outdoor temperatures sufficiently low, moisture will condense
on the wall surfaces within the occupied spaces. Once moisture
condenses on the wall surfaces, dust and smoke particles can
collect in these areas and will remain once the wall surface
has dried.
Thermal patterns caused by dust and condensation
are readily observed for light-colored walls with smooth surfaces
such as drywall coated with smooth latex paint. The intensity
of the resulting dust patterns will be dependent upon humidity
levels, wall temperatures, and the amount of particulates
within the air.
Typically dust patterns are more intense
within areas occupied by smokers, within kitchens, near woodstoves
or fireplaces, or in areas where candles are burned. Over
time, dust patterns can become quite pronounced and will often
clearly show every framing member and insulation deficiency
within the wall.
Infrared inspection of building envelopes
is one of the many topics covered in the Level I Infraspection
Institute Certified Infrared Thermographer® training course.
For information on thermographer training including course
locations and dates, visit us online at www.infraspection.com
or call us at 609-239-4788.
Visit
Infraspection Institute Web Site
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| March
17, 2008 Sponsored
by:
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Infrared Inspection of Load Break Elbows
Tip
written by: Infraspection Institute
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Load break elbows are a common
feature on shielded cables. Thermography may be used to provide
evidence of loose or deteriorated connections associated with
these connectors.
Load break elbows are insulated plug-type
terminals typically used to terminate shielded, underground
cables. Load break elbows act as large power plugs for connecting
cables to transformers, switching cabinets and bushings equipped
with load break receptacle bushings.
Internal to load break elbows are several
mechanical connections each of which is subject to deterioration
over time. A typical elbow contains a crimp connection and
a pin electrode that screws into the elbow. During normal
operation, this pin electrode mates with a receptacle which
also contains mechanical connections. Elbows and receptacles
that have loose or deteriorated connections will operate at
elevated temperatures and are readily detectable with a thermal
imager.
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Thermogram shows hot elbow
due to loose internal connection.
~ Images
courtesy Jim Lancaster
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Normally, all electrical connections within
an elbow are hidden from view due to the elbow’s molded
rubber insulating body. Due to their high emittance, load
break elbows are excellent candidates for infrared inspections.
In fact, thermal imaging is one of the best ways to inspect
these components for the integrity of their connections.
Since line-of-sight access to the electrical
connections within load break elbows is not possible, temperatures
at the point of origin are likely to be much hotter than observed
temperature values on the exterior surface. Small Delta T’s
observed on the surface of elbows can be indicative of a serious
problem. Because of this, hot load break elbows should be
investigated for cause as soon as possible and appropriate
corrective measures taken.
Infrared inspection of power distribution
systems is one of the many topics covered in the Level I Infraspection
Institute Certified Infrared Thermographer® training course.
For information on thermographer training including course
locations and dates, visit us online at www.infraspection.com
or call us at 609-239-4788.
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Infraspection Institute Web Site
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| March
25, 2008 Sponsored
by:
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Many infrared imagers utilize
PC cards to store imagery and data. Due to advances in technology,
storage capacity of flash cards has increased. Unfortunately,
some older thermal imagers will not work with newer, large
capacity flash cards.
PC cards, also known as flash cards, first
appeared as removable storage media on some thermal imagers
beginning in 1995. At that time, the average capacity of PC
cards was 5 MB of data. Over time, the storage capacity of
PC cards has increased dramatically. As of 2008, several thermal
imagers are using PC cards with a capacity of 1 GB or more.
Newer infrared imagers, digital cameras,
pocket pc’s and other devices are likely able to recognize,
read and use smaller capacity PC cards. Older thermal imagers
and electronics may not work with a larger and faster PC card
such as those with 1GB or greater capacity.
With the fast changing digital electronics
market and the demand for larger memory cards, smaller capacity
PC cards are becoming more difficult to find. Most electronic
stores and large retail stores no longer carry PC cards smaller
than 1 GB. Some camera stores still have a limited selection
of the smaller capacity PC cards.
In some instances, it is possible to
use memory card adaptors such as, xD to CF; however, success
is sometimes limited. For example, it may be possible to save
data onto a memory card, but not read or view the data previously
saved on the same device. If you have a thermal imager that
is not compatible with modern PC cards, it may be wise to
obtain compatible PC cards while they are still available.
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| March
31, 2008 Sponsored
by:
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Safe Air Travel with Batteries and
Devices
~
Tip written by: Infraspection Institute
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Many electronic devices including
infrared imagers are powered by lithium batteries. Effective
January 1, 2008, US Department of Transportation regulations
prohibit loose lithium batteries in checked baggage onboard
aircraft.
Spare
batteries, also called “loose” batteries, are
batteries which are not installed in equipment. A lithium
ion battery inside your computer is an installed battery.
A battery you carry separately in case that battery runs low
is a spare battery.
Effective January 1, 2008, you may not pack
spare lithium batteries in your checked baggage. You may pack
spare lithium batteries in your carry-on baggage. The following
are tips for packing spare batteries:
o Pack spare batteries in carry-on baggage.
In the passenger compartment, flight crews can better monitor
safety conditions to prevent an incident, and can access
fire extinguishers, if an incident does happen.
o Keep spare batteries in the original
retail packaging, to prevent unintentional activation or
short-circuiting.
o For loose batteries, place tape across
the battery's contacts to isolate terminals. Isolating terminals
prevents short-circuiting.
o If original packaging is not available,
effectively insulate battery terminals by isolating spare
batteries from contact with other batteries and metal. Place
each battery in its own protective case, plastic bag, or
package. Do not permit a loose battery to come in contact
with metal objects, such as coins, keys, or jewelry.
For personal use, there is generally no restriction
on the number of spare batteries allowed in carry-on baggage.
This is the case for cell phone batteries, "hearing aid"
button cells, and AA batteries/AAA batteries available in
retail stores, as well as almost all standard laptop computer
batteries.
For some devices, lithium batteries are permitted
in checked luggage provided they are installed in the device.
If you pack a device containing batteries, secure it against
activation by locking the activation switch in the "off"
position, placing the device in a protective case, or by other
appropriate measures.
For more information, visit the TSA
website.
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Infraspection Institute Web Site
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| April
7, 2008 Sponsored
by:
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Infrared inspections of electrical
systems often include high visibility equipment such as substations,
switchgear and motor controllers. In this Tip we discuss several
critical items that are often overlooked during infrared inspections.
Perhaps one of the most overlooked pieces
of equipment during an infrared inspection of electrical substations
and indoor electrical switchgear is the control cabinets located
beneath breakers in outdoor substations and above or on the
side of rack-in breaker bays on 480V and higher indoor switchgear.
Equipment inside these cabinets is comprised
of both AC and DC current and includes relays, conductor terminal
connections, current transformers, breakers, and fuses. The
primary function of this equipment is to activate the trip
mechanism of a breaker if voltage or current conditions fall
outside the specified trip settings.
Connection failures and other heat related
damage to equipment inside these cabinets can cause a breaker
to trip resulting in widespread power outage throughout a
community and/or a facility. Given the vital importance of
this equipment, it should be on every thermographer’s
inventory list to inspect.
Below are a few examples of thermal
problems that can be detected in these cabinets: 1) Image
1 shows internal heating on a breaker, 2) image
2 shows heating of a impregnated ribbon bus on a
relay circuit board, and 3) image 3 show
heating on a plug-in fuse responsible for the switchgear cabinet
heater.
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| April
14, 2008 Sponsored
by:
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Spring is the Time for Infrared Roof
Inspections
~
Tip written by: Infraspection
Institute
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With onset of warmer weather,
the harshness of winter is but a fading memory for most. Left
undetected, the damage caused by winter’s fury is a
reality that can lead to premature roof failure. Fortunately,
an infrared inspection of your roof can detect evidence of
problems before they can get out of hand.
Performed under the proper conditions with
the right equipment, an infrared inspection can detect evidence
of latent moisture within the roofing system often before
leaks become evident in the building.
The best candidates for infrared inspection
are flat or low slope roofs where the insulation is located
between the roof deck and the membrane and is in direct contact
with the underside of the membrane. Applicable constructions
are roofs with either smooth or gravel-surfaced, built-up
or single-ply membranes. If gravel is present, it should be
less than ½” in diameter and less than 1”
thick.
For smooth-surfaced roofs, a short wave
(2-5.6 µ) imager will provide more accurate results
especially if the roof is painted with a reflective coating.
All infrared data should be verified by a qualified roofing
professional via core sampling or invasive moisture meter
readings.
Infrared inspection of flat roofs and proper
equipment selection are two of the many topics covered in
the Infraspection Institute Level I Certified Infrared Thermographer®
training course. For more information or to register for a
course, visit Infraspection
Institute or call us at 609-239-4788.
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Infraspection Institute Web Site
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| April
22, 2008 Sponsored
by:
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A common question among thermographers
who perform infrared inspections of buildings is, “What
emissivity setting should I use?” While this might seem
like a straightforward question, the answer is not that simple.
Recent years have seen a dramatic increase
in the use of thermography as a building diagnostics tool.
While many applications are qualitative, there are occasions
when quantifying temperature can be useful. In order to accurately
perform non-contact temperature measurements, one must input
the correct emittance value into a radiometer’s computer.
While many equate emissivity to values published
in emittance tables, emissivity is a dynamic characteristic
that is influenced by several factors. These include: wavelength,
object temperature, viewing angle, target shape, and surface
condition. Each of these factors can vary between projects
or during a given inspection.
Further compounding the challenge is the
fact that not all imagers are created equal. Imagers lacking
corrective inputs for atmospheric attenuation and/or reflected
temperature often require an exaggerated emittance value be
utilized.
When performing an infrared inspection of
buildings, keep the following in mind:
- For qualitative inspections performed
with an imaging radiometer, leave the imager’s E control
set to 1.0. If possible, turn off all temperature measurement
tools.
- In general, dielectric materials will
have a relatively high emittance; shiny surfaces and glass
will be quite reflective.
- Viewing angle and reflected temperature
can greatly influence the effective emittance of a material.
In particular, smooth-surface roof membranes and building
sidewalls can be quite reflective when imaged at low viewing
angles often associated with ground-based inspections.
Lastly, emittance values obtained from
published tables can introduce significant temperature measurement
errors. Whenever possible, one should calculate emittance
values with the subject imager and cross verify observed temperatures
with contact thermometry.
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| April
30, 2008 Sponsored
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Infrared Inspections
of Control Panels
Containing Exposed Contacts
~ Tip provided
by Michael Sharlon,
Thermasearch of Arkansas
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Infrared inspections of relay
panels containing exposed electrical contacts can be hazardous
to your imager’s health! This is especially so when
viewing elevator contact switchboards where momentary arcs
are visible.
Electrical control panels are items that
are frequently included in an infrared inspection of electrical
distribution systems. Even though most of these relays operate
at or around 120 volts AC and 50/60 Hz, the arc that occurs
at break generates high intensity electromagnetic pulses that
your imager’s shielding can rarely handle at distances
of less than four feet.
If many relays are actuating randomly you
may see momentary wavering to all out loss of vertical sync
resulting in a total skewing of the imager’s display
screen. The variation in intensity is directly related to
how close you are to the subject panel.
To minimize the effects of pulsing associated
with operating relays, maintain a distance of at least six
feet when viewing these panels. Doing so will eliminate or
minimize any adverse effect on your imager’s display.
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| May
6, 2008 Sponsored
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Focus, Focus, Focus
Tip written by:
Infraspection Institute
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Proper image focus is still
one of the most important aspects of performing an infrared
inspection. A clear image not only allows for optimal problem
diagnosis, but it is also critical to accurate temperature
measurement.
Clear focus is not difficult to achieve if
you follow a few simple steps:
- Get as close as safely possible to your
target
- Take time to carefully focus for optimum clarity. This
may take some practice if you have a motorized focus mechanism.
- Ascertain that your target is stationary.
- Only shoot from a stable platform. If
imaging from a motor vehicle, it may be desirable to shut
off the engine to avoid vibration.
- Be sure your imager is steady as you
capture the image. Gently push the store button rather than
punching it.
- If using a handheld imager, consider
using a tripod or monopod to help stabilize your imager.
Once you’ve stored an image,
recall and check for clarity. If the results are less than
perfect, start over. In addition to greater accuracy, capturing
clear images makes it easier to convey information to the
end user and/or the person who will eventually perform corrective
actions.
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| May
12, 2008 Sponsored
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Fire Resistant Clothing
Tip written by:
Infraspection Institute
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Fire Resistant Clothing is
required Personal Protective Equipment for many who work in
high temperature areas or near energized electrical equipment.
If your job requires the use of FRC, there are several important
things of which you should be aware.
Not all garments classified as FRC are created
equal. When choosing FRC you should be aware that:
- FRC is not fireproof. It is designed
to protect the wearer from burns by resisting ignition during
brief periods of high temperature exposure such as electrical
arc flashes.
- FRC is manufactured with different materials
and different weights. Be certain that the chosen material
is appropriate for the task at hand.
- FRC effectiveness can be compromised
by age, wear, contamination with flammable materials and
the attachment of name patches or embroidery. FRC can be
permanently damaged by improper cleaning or laundering.
- FRC is only effective when it is worn
properly. It should always be worn as the outer-most garment.
If worn over other layers clothing, the undergarments should
be made of natural fiber and completely covered by the FRC.
Before wearing FRC, be certain to understand
its proper application and limitations and how to use it properly.
As always, remember to work safely!
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| May
19, 2008 Sponsored
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Safety – It
Takes Two
Tip written by:
Infraspection Institute
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If you are a thermographer
who performs infrared inspections of electrical distribution
systems, you are not alone and you never should be. Working
alone near exposed, energized electrical equipment is not
only dangerous, it is a violation of federal law!
Administered by OSHA, the Occupational Safety
and Health Standards for General Industry, 29 CFR, Part 1910
apply to most thermographers working within the United States
or its territories. Specifically, 1910 Subpart R covers the
operation and maintenance of electric power generation, control,
transformation, transmission and distribution lines or equipment.
Covered facilities include utilities and equivalent industrial
establishments.
According to Subpart R, prior to the commencement
of work, medical and first aid supplies must be provided for,
including persons trained in first aid and CPR when work is
on or near exposed lines or equipment energized at greater
than 50 volts. Since CPR cannot be self-administered, at least
two people trained in first aid and CPR must always be present
when working near most exposed energized equipment.
When performing infrared inspections
in the future, having a second CPR trained person along will
not only satisfy OSHA requirements, it may save your life
should an accident occur!
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| May
26, 2008 Sponsored
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Protecting Against
West Nile Virus
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The onset of seasonably warmer
weather signals that Summer has returned. For many, it also
means the return of mosquitoes and the threat of West Nile
virus.
West Nile Virus (WNV) infection is an illness
transmitted to humans primarily by mosquitoes. Flooded areas,
particularly in warm climates, provide ideal conditions for
mosquitoes to breed in stagnant water. Bites from infected
mosquitoes may result in illnesses which range from mild flu-like
conditions (West Nile fever) to severe and sometimes life-threatening
diseases requiring hospitalization (West Nile encephalitis
or meningitis). If you have symptoms of severe illness, seek
immediate medical assistance.
Signs & Symptoms
of West Nile Fever
(mild illness)
- Headache, fever, body aches
- Swollen lymph nodes, and/or a skin rash
on the body
Signs & Symptoms
of West Nile Encephalitis or Meningitis
(severe illness)
- Headache, high fever, stiff neck
- Disorientation (in very severe cases,
coma)
- Tremors, convulsions and muscle weakness
(in very severe cases, paralysis
Preventing Mosquito
Exposure
- Reduce or eliminate mosquito breeding
grounds (i.e., sources of stagnant or standing water)
- Cover as much skin as possible by wearing
long-sleeved shirts, long pants and socks when possible
- Avoid use of perfumes and colognes when
working outdoors
- Use an insect repellent containing DEET
or Picaridin on skin that is not covered by clothing
- Spray insect repellent on the outside
of your clothing (mosquitoes can bite through thin clothing).
Do not spray insect repellent on skin that is under clothing.
- Do not spray aerosol or pump products
in enclosed areas or directly on your face. Do not allow
insect repellent to contact your eyes or mouth. Do not use
repellents on cuts, wounds or irritated skin.
- After working, use soap and water to
wash skin and clothing that has been treated with insect
repellent
- Be extra vigilant from dusk to dawn
when mosquitoes are most active
Thermographer safety is one of the topics
covered in all Infraspection Institute Certified Infrared ThermographerŪ
training courses. For information on thermographer training
and certification, visit us online at www.infraspection.com
or call us at 609-239-4788. For more complete information on
workplace safety, visit the OSHA
website. Visit
Infraspection Institute Web Site |
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| June
3, 2008 Sponsored
by:
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Post Processing
Thermal Images
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Post processing of thermal
images is a common practice for many thermographers. While
image processing may provide a measure of convenience for
some, it can have significant drawbacks.
For many thermal imagers, infrared images
can be stored in 12 bit format. Saving thermal images in 12
bit format allows thermal images to be recalled at any time
and post processed for level, gain and color palette. For
imaging radiometers, temperature measurement settings such
as emittance may also be changed. Post processing may take
place within the imager or through a separate personal computer
using the manufacturer's proprietary software.
Over time, many thermographers have adopted
a policy of quickly recording imagery in the field and then
returning to the comfort of their office to further process
their imagery. Although post processing affords the thermographer
a variety of options for image analysis, one should be aware
that post processing can be time consuming. Spending as little
as five minutes processing imagery can result in a substantial
increase in report preparation time.
In addition to wasted time, post processing
may invalidate imagery as legal evidence. Not unlike digital
photography, thermal images that have been post processed
are creations and not originals. Should a thermographer’s
report be introduced in a claim, a competent opponent will
likely question if the imagery is original. In such situations,
a thermographer must be able to affirm that his/her report
does not contain processed imagery.
In light of the above, we recommend that
thermographers store images exactly the way they will appear
in their report and endeavor to avoid post processing altogether.
Image recording and reporting are two
of the many topics covered in all Infraspection Institute
Certified Infrared Thermographer® training courses. For
information on thermographer training and certification, visit
us online at www.infraspection.com or call us at 609-239-4788.
Visit
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| June
9, 2008 Sponsored
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The Myth Behind
IFOV Values
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A specification commonly
provided for thermal imagers is Instantaneous Field of View
or IFOV. Many people mistakenly believe that IFOV values provide
meaningful information about a thermal imager’s performance.
Unfortunately, this is simply not true.
Originally developed for evaluating the
optical performance of thermal imaging systems, IFOV values
were intended to allow a user to calculate the minimum target
size needed to achieve 50% probability of detection at any
given distance. Using IFOV values to evaluate modern thermal
imagers and radiometers is unreliable for several reasons:
o To date, there is no accepted standard
for determining IFOV. Consequently, imager manufacturers
calculate IFOV values differently, making test results impossible
to compare.
o Because IFOV values are reported for
a single pixel, they cannot be used to accurately calculate
spot measurement size for imaging radiometers since accurate
temperature measurement requires several pixels, not just
one.
o Stated IFOV values are traditionally
reported at 50% radiance or less which is unreliable for
both temperature measurement and accurate thermal imaging.
The Infraspection Institute Standard for
Measuring Distance/Target Size Values for Infrared Imaging
Radiometers provides a simple and effective method for determining
spot measurement size for any quantitative infrared imager.
Proper use of this standard is taught in all Infraspection
Institute Level II training courses.
For more information on thermographer
training and certification or to obtain a copy of the standard,
visit us online at www.infraspection.com
or call us at 609-239-4788.
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| June
17, 2008 Sponsored
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Video Output –
A Useful Feature on Thermal Imagers
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Purchasers of thermal imagers
are often faced with the challenge of which features to look
for on new equipment. For some, a video output jack can be
a particularly useful feature.
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