Introduction - Beha-Amprobe ULD-400-EUR Serie Manuel De L'utilisateur

2. INTRODUCTION

Ultrasonic sound, or ultrasound, is a sound wave with frequencies above 20 kHz, higher
than the upper audible limit of human hearing. Ultrasound can be generated when
turbulence created by air or gas is forced through a small orifice. Leaking air or gas is
generally considered to be viscous flow, and as the flow velocity increases, the frequency
of the ultrasound emitted becomes higher. Vibrating, moving objects or electric discharge
will also create an ultrasonic wave, which is very directional in nature and can be used to
pinpoint the exact location of a leak, vibration or discharge.
The ULD-400-RE Receiver detects ultrasounds within 20 kHz to 90 kHz frequency, then
amplifies and converts these ultrasonic sounds to frequencies and levels that the human
ear can hear through headphones and show it on the LCD screen. The 20 kHz to 90 kHz
frequency range is the optimal range for detecting a variety of leakage events in assets such
as HVAC systems and pneumatic lines. A change in the ultrasound produced by an asset may
be indicative that an asset is beginning to fail.
0 20 Hz 20 kHz 20 MHz 200 MHz
Infrasound Acoustic Sound Ultrasound
Figure 2: Sound range spectrum
3