Ultrasound Technology and Compressed Air Audits

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Ultrasound Technology and Compressed Air Audits
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Brief Overview of Ultrasound

• Ultrasonic frequencies are high frequency signals
  that are above range of human hearing.
• Human hearing range is 20 Hz to 20 kHz
• Ultrasound instruments sense 20 kHz to 100 kHz
• High frequencies have characteristics that work
  differently than low frequencies in the audible
  range.

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Low Frequency Sound Waves Range in Size from 3/4
of an inch to 56 feet (assuming the average
hearing is 16.5 kHz)
High Frequency (Ultrasound) Sound Waves Range In
Size from 1/8 of an inch to 5/8 of an
inch (assuming ultrasound range from 20
kHz-100kHz)
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Ultrasonic Characteristics

• Characteristics of short wave sounds
• They are directional/detectable
• They are localized to the source of emission
• They will reflect and not penetrate solid objects
  making them easy to block/shield
• They can be sensed in loud, noisy environments
• Subtle changes can be noted to provide early
  warning of failure

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SOUND PENETRATION

• Low Frequency Wave
• Vibrate Solid Surfaces
• Large Objects Appear Transparent
• High Frequency Wave
• Short
• Weak
• Can not Penetrate Solid Objects

MPEG SUPERSONIC FLYBY OF AN F14 SHOWING THE
SOUND WAVE WITH A VAPOR CLOUD
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How Do We Detect Ultrasound?

• Using a digital ultrasonic translator which
  provides
• Display Screens with test data including Decibel
  and Frequency read outs.
• Software for data management
• Sound recording ability and sound analysis
  software

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TYPICAL ULTRASONIC TRANSLATOR
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How Do these Ultrasonic Translators Work?

• The Ultrasound is detected and these sounds are
  then translated down into lower frequencies
  within the range of human hearing
• They are heard through headphones
• And observed as intensity increments on a meter
  or display panel.

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Interchangeable Modules

• Leaks Are Detected By
• Scanning Module
• Stethoscope Module
• Tone method
• Specialized Methods May Be Considered
• Long Range Module Non Accessible Leaks
• Liquid Leak Amplifier
• Laminar or TINY Leaks

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Sound Recording

• The translated ultrasound samples
• can be recorded for further analysis.
• Use the heterodyned output the headphone jack
  and connect to a suitable recording device.
• The captured sound can be analyzed using Spectral
  Analysis Software.

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Where Do Air Leaks Occur?

• Mechanical Seals
• Threaded Fittings
• Sealant Problems
• Gaskets
• Corrosion/Erosion
• Structure Penetrations

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Considerations in Leak Detection

• Turbulence
• Orifice Shape
• Fluid Characteristics
  Viscosity Molecular Wt.
• Pressure Differentials
• Distance From Leak
• Competing Ultrasounds
• Accessibility to Leak
• Atmospheric Conditions

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Turbulence
Turbulent Leaks Emit Ultrasound Based on Their
Shape, Pressure At the Leak, and other Factors
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ORIFICE
Shape of the Orifice is the Determining Factor in
How Much Detectable Ultrasound is Present
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How An Air Leak Generates Ultrasound
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Relating Sound Levels to CFM
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Conducting a Compressed Air Survey

• Gather Data
• Compressor Info
• PSIG Operating data
• Hours of Operation
• Begin Survey at Compressor
• Follow Air Lines to all Pieces of Equipment
• Record dB Readings of Leaks
• Take Photographs of Leaks

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How do we do this?

• Create a route
• Set up the instrument
• Gather relevant data
• Test, listen, record
• Data log
• Generate Report

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Create A Route

• Plan carefully
• With plant personnel, determine the optimal route
  for inspection and ease of follow up for repair.
• Create a method of equipment identification (if
  none exists)

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Set Up Instrument

• Verify the sensitivity it should be working the
  same from one inspection to the next.
• What frequency to use record this for
  consistency
• What test module to use?

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Gather Relevant Data

• Date and Time
• Compressor Data
• Operating Pressures
• Hours Operation
• Any Special or Hazardous Conditions

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Test, Listen, Record
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Data Log

• Data log all readings
• Take Photographs of all leaks

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Generate a Cost Report

• Place Recorded dB Readings in Analysis Software
• Generate Report of dB Sound Level of Each Leak
  Converted to CFM with Associated kW Usage and
  Annual Cost of Leak

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Place Pictures with Report

• Place Photos of Each Leak Location that
  Numerically Matches the Cost Report

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AIR LEAKS COST !!!!!!

• LEAK DIA AIR-LOSS LOSS/DAY LOSS/DAY
  LOSS/YR. CFM CU.FT/DAY
• --------------------------------------------------
  -------------------------------------------------
• 1/64 .40
  576 0.14 50.40
• 1/32 1.60 2,304 0.58 211.00
• 3/64 3.66 5,270 1.32 481.00
• 1/16 6.45 9,288 2.32 846.00
• 3/32 14.50 20,880 5.22 1,904.00
• 1/8 25.80 37,152 9.29 3,389.00
• 3/16 58.30 83,952
  21.00 7,661.00
• 1/4 103.00 148,320 37.08
  13,526.00
• 5/16 162.00 233,280 58.32
  21,275.00
• 3/8 234.00 336,960 84.24
  30,731.00
• ---------------------------------------------
  ------------------------------------------
• NOTE Based on 100 PSI, 0.25 /mcf, 8760
  hours / year

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Questions on Leak Detection?
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Other Uses for Ultrasonic Inspection

• Electrical
• Corona
• Tracking
• Arcing
• Detecting Interference
• Lubrication
• Motor Testing
• Complements Infrared

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ELECTRIC INSPECTION

• CORONA
• TRACKING
• ARCING

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WHAT ULTRASOUND FOUND AND INFRARED MISSED
Here We See A 138KV Line In A Substation That Had
a Wire That Was Corroded Due To Corona. It Broke
Loose And Welded Itself Back To Another Point
Due To The High Current Load. This Was NOT
Detected By The System Monitors!!
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OVER LUBRICATION

• AN EXAMPLE OFOVER LUBRICATION
  BARE WIRE

Bad Being Lubricated
Good
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Conclusion

• ULTRASOUND
• Versatile
• Simple to use
• Provides definitive data of air leaks
• Supports other technologies
• QUESTIONS??? THANK YOU