aural thermal methods
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CONDITION MONITORING
AURAL METHOD Hearing ("auditory" or "aural") is the ability to
perceive sound by detecting vibrations through an organ such as the ear.
It is one of the traditional five senses. In humans and other vertebrates, hearing is
performed primarily by the auditory system: vibrations are detected by the ear and transduced into nerve impulses that are perceived by the
Like touch, audition requires sensitivity to the movement of molecules in the world outside the organism. Both hearing and touch are types of mechanosensation.
Frequencies capable of being heard by humans are called audio or sonic. The range is typically considered to be between 20 Hz and 20,000 Hz.
Frequencies higher than audio are referred to as ultrasonic, while frequencies below audio are referred to as infrasonic.
In common use, the word noise means any unwanted sound.
Can be used in condition monitoring Noise reduction with distance When one doubles the distance from a noise
source the recorded noise level is reduced by 6 dB. This is also called the Rule of 6
NASA researchers at Glenn Research Center conducting tests on aircraft engine noise in 1967
ULTRASONIC TESTING n ultrasonic testing (UT), very
short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz and occasionally up to 50 MHz are launched into materials to detect internal flaws or to characterize materials.
The technique is also commonly used to determine the thickness of the test object, for example, to monitor pipework corrosion.
Ultrasonic testing is often performed on steel and other metals and alloys, though it can also be used on concrete, wood and composites, albeit with less resolution..
At a construction site, a technician tests a pipeline weld for defects using an ultrasonic phased array instrument. The scanner, which consists of a frame with magnetic wheels, holds the probe in contact with the pipe by a spring. The wet area is the ultrasonic couplant that allows the sound to pass into the pipe wall.
PRINCIPLE OF WORKING In ultrasonic testing, an
ultrasound transducer connected to a diagnostic machine is passed over the object being inspected.
The transducer is typically separated from the test object by a couplant (such as oil) or by water, as in immersion testing.
There are two methods of receiving the ultrasound waveform, reflection and attenuation.
REFLECTION METHOD In reflection (or pulse-echo) mode, the
transducer performs both the sending and the receiving of the pulsed waves as the "sound" is reflected back to the device.
Reflected ultrasound comes from an interface, such as the back wall of the object or from an imperfection within the object.
The diagnostic machine displays these results in the form of a signal with an amplitude representing the intensity of the reflection and the distance, representing the arrival time of the reflection
ATTENUATION In attenuation (or through-transmission) mode,
a transmitter sends ultrasound through one surface, and a separate receiver detects the amount that has reached it on another surface after traveling through the medium.
Imperfections or other conditions in the space between the transmitter and receiver reduce the amount of sound transmitted, thus revealing their presence. Using the couplant increases the efficiency of the process by reducing the losses in the ultrasonic wave energy due to separation between the surfaces
ADVANTAGES High penetrating power, which allows the detection of flaws deep
in the part. High sensitivity, permitting the detection of extremely small flaws. Only one surface need be accessible. Greater accuracy than other nondestructive methods in
determining the depth of internal flaws and the thickness of parts with parallel surfaces.
Some capability of estimating the size, orientation, shape and nature of defects.
Nonhazardous to operations or to nearby personnel and has no effect on equipment and materials in the vicinity.
Capable of portable or highly automated operation.
DISADVANTAGES Manual operation requires careful attention by experienced
technicians Extensive technical knowledge is required for the development of
inspection procedures. Parts that are rough, irregular in shape, very small or thin, or not
homogeneous are difficult to inspect. Surface must be prepared by cleaning and removing loose scale,
paint, etc., although paint that is properly bonded to a surface need not be removed.
Couplants are needed to provide effective transfer of ultrasonic wave energy between transducers and parts being inspected unless a non-contact technique is used. Non-contact techniques include Laser and Electro Magnetic Acoustic Transducers .
Inspected items must be water resistant, when using water based couplants that do not contain rust inhibitors.
TEMPERATURE MONITORING Defects - tribological reasons – energy wasted
in heat energy heats the connected component. Equipment operating at ambient conditions. Temperature rise is monitored to detect any
fault. Different techniques are adopted to detect this
rise Temperature crayons and tapes Thermometers and Optical Pyrometers Softening cones/Wax/Paints Thermocouples and fusible plugs Infrared Meter
Thermography (Infrared Radiation scanner) Bimetallic Strips Theristors Vapour Pressure in Bulb Mercury in Glass etc.
WHAT IS INFRARED THERMOGRAPHY? Infrared thermography uses special cameras
that can detect radiation in the infrared range of the electromagnetic spectrum and produce an image of that radiation.
An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and performs calculations to indicate the temperatures.
CAMERAS - FLIR I60
Courtesy: FLIR Systems
CAMERAS - FLIR T250
Courtesy: FLIR Systems
APPLICATIONS Industrial
Process Control Predictive Maintenance Energy Audits Roofing Diagnostics
APPLICATIONS
Predictive MaintenanceElectrical
ELECTRICAL
Outdoor Switch With Bad Connection
ELECTRICAL
Substation Switch With Corroded Contact
ELECTRICAL
Substation Switch With Corroded Contact
ELECTRICAL
Motor Starter Connection
ELECTRICAL
Battery Inspection
APPLICATIONS
Predictive MaintenanceMechanical
MECHANICAL
Pulley Rubbing a Shroud
MECHANICAL
Coupling Alignment
MECHANICAL
Overheated Motor
APPLICATIONS
Energy Audits
APPLICATIONS
-Energy Audit
Blocked HeatExchanger Tubes
APPLICATIONS
Energy Audits
Refractory Damage
APPLICATIONS
Energy Audits
Process FlowHeat Loss
APPLICATIONS
Energy AuditsInsulation Damage
APPLICATIONS
Roofing DiagnosticsRoof Leaks (Moisture)
INFRARED LIGHT
Discovered in 1800 by Sir Fredrick Herschel
Light Beyond Red
All objects above the temperature of Absolute Zero emit Infrared light.
WHY IS THERMOGRAPHY NEEDED? Infrared thermography has become a
standard predictive maintenance practice to check electrical circuitry for loose connections.
The technology is now being used to scan pumps, steam traps, steam lines, refrigeration systems, manufacturing processes, manufacturing facilities, and HVAC systems.
The technology can provide instant feedback on unsafe or wasteful conditions.
WHAT IS INFRARED THERMOGRAPHY? Heat sensed by an infrared camera can be
precisely measured enabling the user to monitor thermal performance and evaluate the severity of heat-related problems.
Infrared thermography is the only diagnostic technology that can instantly visualize and verify thermal performance.
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight.
Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz.
In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not.
Infrared (IR) light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres ( µm), and extending conventionally to 300 µm.
These wavelengths correspond to a frequency range of approximately 1 to 400 THz, and include most of the thermal radiation emitted by objects near room temperature.
Microscopically, IR light is typically emitted or absorbed by molecules when they change their rotational-vibrational movements.
THERMOGRAPHY Infrared thermography, thermal imaging,
and thermal video are examples of infrared imaging science.
Thermal imaging cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 9000–14,000 nanometres or 9–14 µm) and produce images of that radiation, called thermograms.
Since infrared radiation is emitted by all objects above absolute zero according to the black body radiation law, thermography makes it possible to see one's environment with or without visible illumination.
The amount of radiation emitted by an object increases with temperature; therefore, thermography allows one to see variations in temperature.
When viewed through a thermal imaging camera, warm objects stand out well against cooler backgrounds; humans and other warm-blooded animals become easily visible against the environment, day or night
FACTORS AFFECTING THERMOGRAPHY Possible obstruction between sensor and
target (which is to be monitored) in the form of object, particles, steam and gas molecules, which may absorb, reflect or scatter the radiation before it reaches the sensor.
Background radiations from object, other than target.
Low emissivity
BENEFITS OF INFRARED THERMOMETRY
Can be used for Moving objects Non-contact
applications where sensors would affect results or be difficult to insert or conditions are hazardous
Large distances Very high
temperatures
BENEFITS OF A THERMOGRAPHY PROGRAM Quick problem detection without interrupting
services Prevention of premature failure and extention of
equipment Identification of potentially dangerous or hazardous
equipment Wide temperature range from (-17)oC to 900oC with
filters Can monitor targets in motion and also fragile target Can monitor target electrically charged. Can monitor small and remote items More efficient planning and scheduling. Increased wrench time for maintenance technicians. Decrease in equipment failures. Higher production efficiency, better quality, and
lower maintenance costs.
CONCLUSION Thermography is a predictive maintenance
tool that when properly used can save money within days of the first scan.
The program has saved many companies thousands of dollars annually.
One of the best programs a manufacturing facility can invest in to improve production, quality, worker environment, and save money.
THERMOGRAPHY
Thermography is the use of an
infrared imaging and measurement camera to "see" and "measure" thermal energy emitted from an
object.
APPLICATIONS
Roofing Diagnostics
CONCLUSION
Is there a need for an Infrared Energy Audit
Scheduling of the Survey
Questions??????
INFRARED THERMOGRAPHY
Plant Predictive Maintenance Program
INTRODUCTION What is thermography? Why is thermography needed? Infrared cameras Examples of thermal imaging Program investment and downtime reduction Benefits Conclusion
WHAT IS INFRARED THERMOGRAPHY? Infrared thermography uses special cameras
that can detect radiation in the infrared range of the electromagnetic spectrum and produce an image of that radiation.
An infrared camera is a non-contact device that detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and performs calculations to indicate the temperatures.
WHAT IS INFRARED THERMOGRAPHY? Heat sensed by an infrared camera can be
precisely measured enabling the user to monitor thermal performance and evaluate the severity of heat-related problems.
Infrared thermography is the only diagnostic technology that can instantly visualize and verify thermal performance.
WHY IS THERMOGRAPHY NEEDED? Infrared thermography has become a
standard predictive maintenance practice to check electrical circuitry for loose connections.
The technology is now being used to scan pumps, steam traps, steam lines, refrigeration systems, manufacturing processes, manufacturing facilities, and HVAC systems.
The technology can provide instant feedback on unsafe or wasteful conditions.
CAMERAS - FLIR I60
Courtesy: FLIR Systems
CAMERAS - FLIR T250
Courtesy: FLIR Systems
EXAMPLES OF THERMOGRAPHY
This is a busbar connection that is loose. The scale on the left is the temperature range. The loose connection is producing temperatures close to 175° Fahrenheit.
Courtesy: FLIR Systems
EXAMPLES OF THERMOGRAPHY
This is an example of a 120VAC breaker with a loose connection.
Courtesy: FLIR Systems
PROGRAM INVESTMENT AND DOWNTIME The initial cost of a camera may be high, but
cost justification is evident when the cost of downtime is realized.
The average cost of downtime in a manufacturing environment has been estimated at greater than $20,000 per hour.
PROGRAM INVESTMENT AND DOWNTIME
Unplanned downtime due to equipment failure cost manufacturing plants up to 3% of their annual revenue. Predictive maintenance can save 8% to 12% over reactive maintenance.
The U.S. Federal Energy Management Program estimates that half of electrical failure that occurs in manufacturing environment facilities could have been prevented with a routine maintenance program.
BENEFITS OF A THERMOGRAPHY PROGRAM Early indication of faults and undesirable
conditions. Enable a proactive work-flow model. More efficient planning and scheduling. Increased wrench time for maintenance
technicians. Decrease in equipment failures. Higher production efficiency, better quality,
and lower maintenance costs.
CONCLUSION Thermography is a predictive maintenance
tool that when properly used can save money within days of the first scan.
The program has saved many companies thousands of dollars annually.
One of the best programs a manufacturing facility can invest in to improve production, quality, worker environment, and save money.
WORKS CITED Campbell, Kevin. Plant Engineering. 7 April 2007.
6 November 2008 <http://www.plantengineering.com/article/CA6431534.html>.
FLIR Systems. 18 April 2008. 6 November 2008 <http://www.goinfrared.com/news/news_item/1126/>.
Stockton, Gregory R. Stockton Infrared Thermographic Services. 10 June 2000. 6 November 2008 <http://www.stocktoninfrared.com/PUBLISHED/PDF/low-hang.pdf>.
Wikipedia - The Free Encyclopedia. 10 July 2008. 6 November 2008 <http://en.wikipedia.org/wiki/Thermography>.
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