Infrared Thermography Training
Resource Speaker:
Vincent Jason V. Peñalosa
Level 1 Thermographer
What Is Infrared Thermography?
Infrared thermography is the science of acquisition and analysis of
thermal information from non-contact thermal imaging devices
Why Is It Useful?
It’s non-contact
It keeps the user out of danger
It does not intrude or affect the
target
Why Is It Useful?
It’s two dimensional
Comparison between
areas of the target is
possible
The image allows for
excellent overview of the
target
Thermal images can be
visualised for analysis
Why Is It Useful?
It’s real time
Enables fast scanning of
stationary targets
Enables capture of fast
moving objects
Enables capture of fast
moving thermal patterns
Activity:
What Applications Can You Identify?
Applications:
Condition-based Maintenance
Activity:
Mechanical Inspections
Activity:
Medicine and Veterinary
Activity:
Security and Surveillance
Activity:
Automotive Safety
Activity:
Process Quality Monitoring
Activity:
Building and Facility Management
Activity:
Law Enforcement and Military
Activity:
Gas Detection
Activity:
What Applications Can You Identify?
Choosing The Right Infrared Camera
One for all does not exist!
Resolution
Detector Image - 320 x 240 FPA
Note that IR detectors may
be totally different from LCD
resolution
Choosing The Right Infrared Camera
Thermal Sensitivity and Accuracy
Infrared cameras allow the user to differences in heat as well
as measure these differences. The accuracy of these
measurements is an important factor to consider. Sensitivity is
the smallest temperature difference between two objects that
an IR camera can discern. This specification is typically
measured in mK (milliKelvin).
Adequate sensitivity is deemed as 100mK (0.10 deg C) with a
+/- 5% or 5 deg C accuracy. However, the desired thermal
sensitivity is 50mK (0.05 deg C) +/-2% or 2 deg C accuracy.
Choosing The Right Infrared Camera
Temperature Range/Span
The camera’s temperature range indicates minimum and
maximum temperature readings the camera is able to measure.
The user must determine the camera’s application before
deciding on a camera. The typical entry level camera usually
cannot handle more than 150-200 degrees.
Choosing The Right Infrared Camera
Others:
Screen display
Field controls and adjustments
Ergonomics, durability
VLCM (Visible Light Camera Module)
Flash/LED illumination
PiP/Fusion
Laser
Lens Option (Telephoto/Wide Angle)
Manual Focus
Bluetooth/Wi-Fi
Software
Cost
So You’ve Chosen and Purchased The
Right Camera……
So what's next?
Do you immediately start shooting?
Not yet, we need to understand some
of the fundamentals
Why?
Thermographer?
Back to Basics:
IR Camera Measurement Functions
Level
Span
Back to Basics:
IR Camera Measurement Functions
“SPAN” is the part within the
temperature measurement range
currently in use.
This is the
difference between the highest set
temperature and the lowest set
temperature
“LEVEL” is the centerpoint or
focal point of the SPAN
Back to Basics:
Isotherm
The Isotherm replaces certain colors in the scale
with contrasting palette
Back to Basics: Spot Meter
The Spot Meter shows relative
temperature within a specific spot
Back to Basics: Area Function
The Area Function shows the hottest,
coldest or average temperature within
a specified area
Back to Basics: Capturing an Image
Capturing an image is done by freezing or storing it, or
both in consecutive order. For reporting purposes the
image must be stored in the camera and transferred to a
report software.
VERY IMPORTANT!
3 Things that cannot be changed after freezing or storing
the image
Temperature Range
Optical Focusing
Image Composition
Back to Basics: Capturing an Image
Temperature Range:
You have to set a range that includes what you want to measure. If the
temperature measurement is not within range, the measurement precision
is inconclusive.
Optical Focusing:
A poorly focused image reflect very badly on the thermographer, and looks
very unprofessional. Your reports are usually the only part of your work
that other people see, this is where their impression of your work is
created. Unfocused images will give false temperature readings.
Image Composition:
The general rule is if you’re too far away, you cannot measure temperature
properly.
Basic Thermal Science
What Is Temperature
Heat and Temperature
What Is Heat?
The total kinetic energy of the molecules that composes it.
Hotter molecules move faster
Cooler molecules move slower
The speed of the molecules will correspond to a temperature level
The substance will contain a certain amount of heat
Heat is a form of energy
Heat is created by conversion of other forms of energy
An object can contain heat, or thermal energy
Heat and Temperature: Moving Molecules
Molecules in a substance are always moving
The hotter it is the faster the movement of molecules
The colder it is the slower the movement
Heat VS. Temperature
The concepts of temperature and and heat are difficult to keep apart. Example, if we take
two objects both 100 deg C and containing 100 joules, and add them together, the
temperature will not be twice as high. There will however, be twice as much energy in the
resulting combination.
Temperature Defined
Temperature is a measure of the average speed of the
molecules and atoms that make up the substance
Temperature describes the condition an object is in
Temperature is not a form of energy, temperature will generally rise and fall as the
thermal energy of an object increases or decreases
Temperature is a byproduct of more or less energy
Temperature will not tell us how much energy is stored in an object
Units for Measuring Temperature
There are generally 3 units of
measurement °Kelvin, °Celsius,
°Fahrenheit
For
purposes
of
thermography, °K is used as
standard. However °C and °F
are widely used
How Cold Can It Get
Absolute Zero Temperature is the theoretical temperature
measurement of an object where the molecules are in a stand still
or no motion at all
Absolute & Relative Temperature Scales
Absolute Zero is the logical
starting point for absolute
temperature scales, thus
how it is defined.
The most common relative
temperature scale is the
Celsius and Fahrenheit scale
Relative temperature are
conveniently adapted for
everyday use
Comparing Temperature Scales
Thermal Science
Rules of Thermal Science
The sum of the total energy contained in a closed system is
constant, therefore, energy cannot be created nor destroyed, only
converted from one form to another
Rules of Thermal Science
Direction of Heat Flow
Heat will spontaneously flow from hotter to colder, thereby
transferring heat from one body or place to another
Basic Heat Transfer Modes
Heat Transfer Modes:
Conduction
Convection
Evaporation/Condensation
Radiation
Basic Heat Transfer Mode: Conduction
Direct transfer from molecule to molecule
Transfer of energy of movement (kinetic energy) between molecules
Can occur in solids, liquids, and gasses
It is the only one that occurs in solids
Basic Heat Transfer Mode: Conduction
Conduction Heat Transfer Rate
The rate of heat flow under steady state conditions is directly proportional
to the thermal conductivity of the object, the cross section of the object
through which the heat flows, and the temperature difference between the
two ends of the object. It is inversely proportional to the length, or
thickness of the object.
Basic Heat Transfer Mode: Conduction
Where:
k = Thermal Conductivity
A = Area or Cross Section
T1 – T2 = Temperature Difference
L = Conductive Path Length
*This is only for temperatures in the “Steady State”
Basic Heat Transfer Mode: Conduction
Basic Heat Transfer Mode: Conduction
Basic Heat Transfer Mode: Conduction
Why is it hotter or colder in the ceiling?
Why is room temperature hotter or colder than outside temperature?
Basic Heat Transfer Mode: Conduction
Steady and Transient State
A stable condition without changes in temperature, and with constant rate of heat flow is termed as “Steady
State”. This means that the heating power (A) and cooling power (B) are the same, therefore so is ΔT.
A Transient Condition is one where changes in temperature and heat flow rate occur. Example, if the heating
power is greater than the cooling power, the object will heat up, thus relevant temperature increase. Should
heating power decrease or stop, the object will start cooling down to ambient state.
Thermal Capacity
Conductivity will not determine
how much heat is required to differ
steady to transient state
Convection
Convection is a heat transfer mode where a fluid is brought into
motion, either by gravity or another force, thereby transferring
heat from one place to another
Heat transfer by moving fluids (liquids, gas)
Can occur in liquids and gasses, not solids
Can create difficulties for thermographers
Convection
Forced Convection
Natural Convection
The fluid is affected purely by gravitational
forces around the object of study
The fluid is directly affected by an outside
force ie, wind, fan pump, etc
Convection
No Wind Influence
With Wind Influence
Radiation Heat Transfer
Heat transfer by emission and absorption of thermal radiation is
called radiation heat transfer
Thermal radiation is a kind of electromagnetic radiation
All objects emit thermal radiation
No medium is required
Passes easily through most gasses
Will pass with difficulty, or be blocked by liquids and solids
Radiation Heat Transfer
Heat is transferred by emission and absorption
Both objects emit and absorb radiation
The net heat transfer is the difference
Radiation Heat Exchange
What are ways that radiation can be
exchanged between object?
Emission – gives off radiation
Absorption – to receive and retain radiation
Reflection – to bounce radiation back
Transmission – to let radiation pass through
Incident Radiation
Incident radiation is all the radiation that strikes an
object from it’s surroundings
Wα + Wρ + Wτ = Wincd = 100%
Radiation Heat Exchange
How do we know what the proportion of the
radiation is?
Absorbed?
Reflected?
Transmitted?
Greatly depend on the properties of the object
α+ρ+τ=1
An object will have a certain capacity to either:
Absorb – absorptivity α
Reflect – reflectivity ρ
Transmit – transmisivity τ
Radiation Heat Exchange
Excitant Radiation
Excitant radiation is all the radiation that leaves the surface of an object,
regardless of its original sources
The first part of excitant radiation we look at is the part that originates
from the target object
An object will have a certain capacity to emit, called emissivity ε
Radiation Heat Exchange
Radiation Wε is emitted in all directions
Dependent on temperature and emissivity
Higher temperature = more radiation
Higher emissivity = more radiation
It is the combination of temperature and emissivity that determine
radiated power
Radiation Heat Exchange
Radiation Heat Exchange
Of the total exitant radiation from a target, a certain proportion will be:
Emitted, from the object itself
Reflected from a source in front of the object
Transmitted, from a source behind the object
Wε + Wρ + Wτ = Wexit = 100%
Radiation Heat Exchange
“The capability of an object to absorb incident radiated energy is
always the same as the capacity to emit its own energy as radiation”
α=ε
Black Body
“An imaginary object, where it absorbs 100% of
incident radiation, and emit 100% of its energy as
radiation”
Black bodies are simulated and are used to calibrate IR
devices
α = 1 (and ρ + τ = 0)
ε = 1 (and ρ + τ = 0)
Real Targets
“Our targets won’t be black bodies”
Most objects are non transmissive, but opaque
When conditions are fulfilled ε + ρ = 1
For real targets we must always consider that
radiation from TWO sources exit the object:
Emitted from the object itself
Reflected from surroundings
Thermal Image Interpretation and
Shooting Techniques
Thermal Image Interpretation and
Shooting Techniques
“High Emissivity: The apparent temperature will be close to the
true temperature of the target”
“Low Emissivity: the apparent temperature will be close to the
apparent temperature of the surrounding objects, hence you
cannot trust what you see”
Thermal Image Interpretation and
Shooting Techniques
Thermal Gradient
Thermal Gradient is a gradual change in temperature over distance
Thermal gradient often indicates the presence of conductive heat transfer
Most of our targets are opaque solids
Conductive heat transfer is the only heat transfer mode in opaque solids
Shows the direction of the heat flow
We analyze thermal gradients
Thermal Analysis Techniques
Important Tools: Pattern Enhancement
Use Thermal Tuning (Level & Span)
Isotherm
Palettes
Thermal Analysis Techniques
Thermal Tuning is the means by providing colors to the image on the
object of analysis, in order to maximize contrast
Thermal Analysis Techniques
No Thermal
Gradient!
Thermal Analysis Techniques
Level and Span
Thermal Analysis Techniques
Thermal Analysis Techniques
Thermal Analysis Techniques
Thermal Gradient
Thermal patterns can be difficult to see:
Three important tools for pattern enhancement
Thermal Tuning
Isotherm
Palettes
Thermal Analysis Techniques:
Thermal Tuning
Thermal tuning means putting the colors of the image on the object of
analysis, in order to maximize contrast
Thermal Analysis Techniques:
Isotherm
The isotherm replaces certain colors in the scale with a contrasting
color. It marks an interval of equal apparent temperature
Thermal Analysis Techniques:
Palettes
The color palette of the image assigns different colors to mark specific levels of
apparent temperature. Palettes can give more or less contrast, depending on the
colors used in them.
Thermal Analysis Techniques:
Palettes
Rule of Thumb
Use high contrast palettes for low contrast targets
Use low contrast palettes for high contrast targets
Thermal Analysis Techniques
How to recognize:
Reflections from spot sources
Emissivity differences
Hot spots will have gradients and will not have straight edges
If the hot spot moves with you, it’s actually a reflection
Thermal Analysis Techniques
Avoiding Spot Reflection:
Do not stand directly in front of your target to avoid reflecting yourself
Move around, if the hot spot moves, it is a reflection
Use angle in = angle out to determine the source so you can avoid it
Use a piece of cardboard or similar to shield off the reflection
Look for thermal gradients, real heating has gradients
Look for parts of the target with high emissivity. They will show less reflections and an
apparent temperature closer to the true temperature
Qualitative & Quantitative Analysis
Qualitative Analysis
Qualitative Thermography relies on analysis of thermal
patterns to reveal the existence and locate the the positions
of anomalies
Quantitative Analysis
Quantitative Thermography uses temperature measurements
to determine the seriousness of an anomaly, in order to
establish repair priorities.
Qualitative & Quantitative Analysis
Qualitative Analysis
Quantitative Analysis
Analyze patterns in the image
Find if there are anomaly
Find where it is located
Apparent temperature only
Usually done first
Used to classify seriousness of the anomaly
Temperature measurement involved
Compensations is made
Not always relevant
Qualitative & Quantitative Analysis
We always need to compare with something:
In electrical we compare:
The phases between each other
A hot connection with the cable
Incoming and outgoing
Qualitative & Quantitative Analysis
Baseline Data:
Baseline data must be systematically and consistently collected
Newly installed or repaired equipment is ideal
In trending applications, the base line becomes an integral part of the process
If you’ve ever asked yourself: “How is this supposed to look?” You probably need base line data
Hot Spot Analysis
Hot Spot Analysis
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: What’s Wrong?
Analysis: It can spell the difference
Analysis: It can spell the difference
Analysis: Its Not All About Hot Spots
Disrupt the norm!
Understand how things work!
What is the process?
Analysis: Its Not All About Hot Spots
Analysis: Its Not All About Hot Spots
Standards According to NETA
Thank you