Introduction

What is Ultrasound? Frequency band of sound: Infrasound Audible SoundUltrasound 20Hz2000Hz / 20Khz Range of most human hearing Low inaudible Soundwaves High inaudible Soundwaves ul-tra-sound is a cyclic sound pressure wave with a frequency greater than the upper limit of human hearing.

Normal SoundUltrasound Characteristics of Ultrasound Waves: Ultrasound waves act physically different than audible sound waves: Stays where it starts Low Penetrating Power Short wavelengths don’t stray from source

Sound Perception Animal Range of frequencies perceived Elephant5 Hz – Hz Humans20 Hz – Hz Dog50 Hz – Hz Cat45 Hz – Hz Bat Hz – Hz Dolphin Hz – Hz Ultrasonic Range = above of human hear perception Infrasonic Range = below of human hear perception

Example Intensity and Distance Inverse Square Rule

Definition of the dB Alexander Graham Bell dB is logarithmic unit used to describe a ratio. The ratio may be power, sound pressure, voltage or intensity. SDT’s reference value is 0dB = 1 µv The Decibel Definition

The Decibel Scale

Ultrasound Applications Generalities

Naturally occurring ultrasound (Passive) Friction Turbulence Electrical Ultrasound Sources

Friction – Bearings – Gear meshing – Coupling – Sheaves and Belts Turbulence – Leaks Internal - External Electrical Passive Ultrasound

Ultrasound Detector Uses different sensors to detect ultrasound waves Converts ultrasound waves into audible sound waves Airborne Sensors Contact Sensors Only detects Ultrasound waves. Audible range sound waves are ignored. +20Khz 

Airborne – Pressure – Vacuum – Steam traps – Electrical Structure borne – Vacuum – Valves & Steam traps – Bearings – Hydraulic Introduction Medium of Transport

Convert inaudible to audible - heterodyne Maintain ultrasound representation Measure ultrasound intensity for trending How it Works

Standard Uses Compressed Air Leaks Steam Traps Condition Monitoring – Bearings, Motors, Fans Acoustic Lubrication Electrical Inspections Tightness Testing ?

Turbulence Leaks in Pressurized Systems Leaks in Vacuum Systems Leaks in Hydraulic Systems Leaks in Steam Systems Friction and Impacts Wear from Mechanical Parts Couplings, Gears, Bearings Electrical Arcing Faults in Electrical Systems Arcing, Tracking, Corona Discharge, RTV Interference Sources of Natural Ultrasonic Noises