Exploring Ultrasound...

PROSARIS operates within the ultrasonic region, using high‑frequency pressure waves to detect leaks and electrical faults that are completely inaudible to humans. With this acoustic foundation in place, we can better understand what ultrasonic detection truly involves and why it is such a powerful diagnostic tool.

We briefly talked about different sources that occur in the different acoustic ranges in our previous blog. Here, let’s take an in-depth look at what can create ultrasonic frequencies. While animals can be a common contributor, we’ll be reviewing examples that are a bit more relevant to us: mechanical, fluid, and electrical systems, and their respective issues and errors.

An array of fluid, electrical, and mechanical systems that may emit various ultrasonic anomalies when malfunctioning or operating inefficiently

Different sources, different ultrasound frequencies

20 kHz

• High-speed electric motors: Bearing defects or frictional wear in motors can produce ultrasonic harmonics in this range.

• Electrical corona discharge: Under certain conditions, corona can emit wideband ultrasonic noise in this range.

• Ultrasonic cleaners: Entry-level ultrasonic baths for cleaning jewelry or lab equipment often use 20 - 25 kHz frequencies.

• Rotating equipment under 300 RPM emit frequencies in the 20 – 25 kHz. Equipment above 300 RPM can produce 28 – 32 kHz.

30 kHz

• Air and other gas leaks (High pressure): Compressed air/gas escaping from openings emit broadband ultrasonic noise with good content in the 30 - 40 kHz range for medium to larger leaks.

• Bearing friction or wear: Failing or poorly lubricated bearings emit ultrasonic signals. 30 kHz is often used for mechanical fault detection, especially when using contact (probe-based) ultrasonic sensors.

40 kHz

• Electrical partial discharge: Arcing and corona discharge can produce impulsive noise in the 20 - 60 kHz range, with 40 kHz commonly used as a detection reference point.

• Ultrasonic transducers: Many commercial ultrasonic sensors (like those used in distance measurement, object detection, or robotics) transmit and receive at exactly 40 kHz.

• Vacuum, air, and other gas leaks (Small/High pressure): High-pressure leaks from very small orifices often emit strongest at 35 - 45 kHz, with 40 kHz often sitting right in the sweet spot.

• Conveyor bearing faults/Friction (High-speed machinery): Subtle friction or cavitation at higher RPMs can push ultrasonic frequencies upwards of 40 kHz.

• Partial discharge events in electrical systems (Corona, surface treeing, tracking, arcing): High-frequency electrical emissions can include components peaking in this range.

• Steam leaks and high-flow turbulence: Escaping steam or turbulent flow in pipes can generate broadband ultrasound with 40 kHz components (ensure you maintain a safe distance from the steam leak while detecting!).

• Power distortion, loose connections and panels, heat sync fans, and other manmade noises can all quickly be identified in this range due to the lack of 50/60 Hz harmonics being present.