Is Your Ultrasound Gun Making You Deaf?

A question often asked by ultrasound inspectors concerns the impact the steady use of ultrasound detectors might have on their hearing. Inspectors should be concerned. Safety is their first right, but everyone needs to own this. Inspectors spend hours in areas that produce constant, deafening background noise. Manufacturers of ultrasound instruments and employers of these inspectors owe it to protect their safety.

Governments also play a role. The United States Department of Labor (OSHA), the Canadian Centre for Occupational Health and Safety (CCOHS), and le Santé et Sécurité au Travail (translates to: Worker’s Health and Safety and carries the abbreviation INRS) all publish acceptable, non-negotiable exposure limits for noise. Here are the tables from European Union, Canada, and the USA.

List of legislated noise exposure in the United States
List of legislated noise exposure in European Community
List of acceptable noise exposure by province

Compliance Responsibility

Here are some ways employers ensure compliance to government regulated safety standards for noise exposure while protecting their employees.

  1. Post signage in high noise zones where hearing protection is mandatory and enforce it with penalties.
  2. Provide employees and visitors with access to approved hearing protection at the entrance to high risk zones.
  3. Conduct regular noise level inspections to ensure compliance and document the results.
  4. Educate employees about their rights and how to protect this important sense.

Safety doesn’t begin, nor end with the employer and the government. It extends to the manufacturer of instruments who also must take responsibility for the goods they produce. Does your ultrasound gun meet the standard of safety your employees deserve? Let’s take a quick look at how an ultrasound detector works to gain a better understanding of the potential risk.

Ultrasound Instruments

The Detector/Processor

An ultrasound detector, whether a gun, or a meter, is an electronic system designed to detect high frequency sounds and convert them to audible sounds. Many plant defects produce sound signals with peaks around 40kHz. The ability to detect, measure, and listen to these defects empowers us to find problems that impact uptime and energy costs. An ultrasound detector is considered the first line of defense in the battle for more reliable and profitable plants.

Inaudible sound pressure waves — around 40kHz — are inconsequential to human hearing. They are produced by Friction, Impacting, and Turbulence. They share three common characteristics in that they are high frequency, short wavelength, and low amplitude. As such, they don’t travel far from their source and are attenuated quickly by their transport medium. On their own, they pose no threat to human hearing.


Ultrasound detectors hear ultrasound with medium-high frequency piezo crystal sensors. Stimulated by the wave’s energy, the crystal produces an extremely low-energy electric voltage. This weak signal is first amplified, and then heterodyned by the ultrasonic meter. Don’t panic, heterodyned is just a fancy word that describes the process of converting inaudible ultrasound into audible sound. Once converted, the signal is made available to the inspector as a measured value, a time waveform and spectral display, and of course audibly, through the headphone output.

SDT270 Safely Transforms Ultrasound to Listening Levels Without Damage to Inspector’s Hearing


Inspectors listen with headphones provided with the instrument. The quality and style of these headphones vary from one manufacturer to another. The key features to look for are:

  • Do they provide sufficient hearing protection from external noise?
  • Do they provide a rich, high-quality sound experience?
  • Do they come equipped with volume adjustment, independent of instrument amplification?

Walkman Style

Walkman style headphones should not be used in industrial workplaces. These foam-covered earpieces have poor sound quality and provide no external hearing protection to the inspector. They are typically supplied with low-cost, low quality instruments. If an ultrasound instrument comes equipped with this style of headset, it is unlikely the manufacturer went to the additional care and expense to implement independent volume controls.

Don’t use this walkman style of headphone in a high noise environment.

Over-the-ear headphones are available in varying quality as well; once again depending on the manufacturer. Higher quality headphones, such as those made by 3M and supplied exclusively by SDT Ultrasound Solutions, provide rich sound quality while providing external hearing protection that exceeds requirements imposed by the USA, EU, and Canadian governments. It’s definitely worthwhile to do your homework and make sure the headset supplied with your ultrasound system are rated to block audible plant noise from reaching your ears.

Headphones from quality manufacturers like SDT protect your hearing and offer crystal clear sound

How Does SDT Work to Protect Your Hearing?

SDT Ultrasound Solutions has a 45+ year history of providing high quality instruments. This Belgian based manufacturer has, at times, been accused of over-engineering their products, but makes no apologies when it comes to the safety of their customers.

Each ultrasound instrument must meet stringent quality and safety standards before it can be released to sell. These standards are engineered at the design concept and rigidly tested and confirmed at the assembly and final production stages. The following declaration applies to SDT200, SDT270, SDT340, LUBExpert, and Checker Range of products.

SDT Commercial Declaration

During design, assembly, and production, SDT takes into consideration noise exposure and the health and safety protection of its customers.

We therefore declare, under our own responsibility, that:

SDT200, SDT270, SDT340, LUBExpert, and Checker Range ultrasound instruments deliver a maximum sound pressure level (SPL) of 79dB typical, when used only with the headsets supplied by SDT, having the references and markings of our company. This declaration is made regardless of the measurement level and/or the audio volume level as adjusted by the user.

SDT makes an additional safety guarantee to our users. When connecting any SDT sensor, or selecting/changing sensors, our instruments automatically self-adjust to a default, maximum sound pressure level of 58dB typical. This applies to all compatible, SDT manufactured sensors. This auto adjustment is done voluntarily by SDT, for the protection and safety of anyone who uses our products.

An audio volume adjustment, which is independent to the signal amplification setting, is a standard feature of all current SDT instruments. This feature enables each operator to adjust the headset volume in a safe, comfortable, and personalized way, without compromising the measurement accuracy of the instrument.

Through the design and engineering of our instruments, it is our intention to meet or exceed safety standards at every level. We are proud to know that all instruments mentioned in this declaration fall within the guidelines set forth by Canadian, American, and European government safety bodies.

Safe inspections from thoughtful, high quality

Final Thoughts

Ultrasound inspectors are exposed to some of the highest noise levels found in their facility. Safety and prevention of hearing loss should be a considering factor when selecting an ultrasound instrument, or using one already on hand. Government legislated exposure levels must be respected by employers, employees, and instrument manufacturers.

It is not enough for manufacturers to simply make a self-declared statement of compliance. They must be prepared to back up their declaration with documented testing procedures and results. Ask for PROOF!

Don’t compromise your hearing. Before you venture into the plant with your ultrasound gun, ask the manufacturer for proof that the headphone output of the ultrasonic gun respects the noise level exposure prescribed by OSHA, CCOHS, and INRS.

Stay safe,

Allan Rienstra

Director, Int’l Business Development
SDT Ultrasound Solutions

Six Signs of a Successful Acoustic Lubrication Program

Six Signs of a Successful Acoustic Lubrication Program

Acoustic Lubrication is just one of the 8 application pillars adopted by world-class ultrasound programs. And what an important one it is. Poor lubrication practices account for as much as 40% of all premature bearing failures. When ultrasound is utilized to assess lubrication needs and schedule grease replenishment intervals, that number drops below 10%. What would 30% fewer bearing related failures mean for your organization?

Keep up with the changes in on-condition bearing lubrication or risk falling behind. For example, Technology advancements from ultrasonic innovator SDT are transforming the way we look at the grease replenishment task. SDT’s LUBExpert, an ultrasound solution that helps grease bearings right, simplifies a complex process into a simple, 2-step procedure.

A successfully implemented world class, acoustic lubrication program delivers many wins for your company. Reduced maintenance costs as well as other savings on grease consumption and less unplanned downtime are two big doors that open other possibilities for factory maintenance teams. Another win will be factory wide efficiency. Properly maintained and lubricated bearings run more efficiently, using less energy and lowering their environmental impact.

With so much innovation available, the question begs, is your lubrication program world-class? Here are six signs to help you decide.

6 Signs your Lubrication Program is on Track

1. A Change in the Quantity of Grease Consumed

Maintenance departments should track grease consumption to monitor and control costs. Root Cause Analysis on failed bearings points to over-greasing as the leading contributor. Bad procedures lead to bearings routinely receiving more grease than they’re designed to handle. The excess ends up being pushed into the motor casing or purged onto the floor. Reduction in grease consumption is a sure sign that your lubrication program is on the right track.

Over lubrication happens when grease replenishment intervals are scheduled based on time instead of condition. Control lubrication tasks with ultrasound to monitor condition and maintain optimal friction. The time between greasing intervals increases, resulting in less grease used per bearing.

Over-greased machines are not only more susceptible to fail, but run less efficiently. Optimally greased bearings draw far less energy and contribute to a greener factory. That alone should be motivation enough to Grease Bearings Right.

2. Fewer Lube Related Failures

Your organization should track failures and perform root cause analysis to eliminate sources of defects.

Optimized greasing programs experience fewer lube-related failures. Less fixing and fire-fighting translates to more creative time for maintenance. Use that time to bring more machines into the greasing program.

Additionally, with ultrasound you find many non-trendable defects. For example, broken or blocked grease pipes and incorrectly fitted grease paths that prevent grease from reaching the bearing.

3. Optimized MRO Spares Management

Your new and improved lubrication program is delivering wins; better control of grease consumption, fewer failures, and more productivity for maintenance. Use this time to study trends and better manage your storeroom.

A decrease in bearing related failures improves spares optimization. Share your ultrasonic lubrication data with your MRO Stores manager to create a plan to reduce the number of emergency parts on hand.

Since you’re taking stock, why not shift some burden to your suppliers? Ask them to confirm your emergency parts against their own stock. If it can be supplied on the same day then why keep it on your balance sheet?

4. Increased Number of Machines Monitored

One benefit of an effective lubrication program is time.

-Time allotted to monitoring machines instead of fixing them.

-Time allotted to correctly assessing the real needs for lubrication.

-Time to look at the big picture.

Take for instance, criticality assessment. Many lubrication programs begin with small steps. All the “A” critical machines receive priority, rightly so. But what about the rest? With more time to plan, organize, and schedule, increase the number of machines acoustically monitored for optimal lubrication.

5. Save Time Combine Acoustic Lubrication and Condition Monitoring

You worked hard for these results. It’s time to use your data for more than just lubrication.

Acoustic lubrication is the proven method to ensure precise bearing lubrication. New technology from SDT, LUBExpert, combines the power of onboard lubrication guidance with Four Condition Indicators for bearing condition assessment.

The time savings from assessing bearing condition during the lubrication process is beyond valuable and another sign your acoustic lubrication program is on the right track.

6. Inspector Confidence at an All-Time High

Reliable machines are the product of an effective lubrication program. You have:

-Managed grease consumption

-Fewer grease related bearing failures

-Optimized MRO spares

-More machines under watch

-Increased data collection intervals

The power of adding ultrasound to your greasing program delivers win after win for reliability. Reliability breeds confidence. More confident inspectors make better decisions and infect a positive culture throughout the organization.

Ultrasound assisted lubrication of plant assets offers significant benefits that calendar based lubrication cannot. Lubrication serves a primary purpose, which is to create a thin layer of lubricant between rolling and sliding elements that reduces friction. So, it makes sense that the best way to determine the lubrication requirement of a machine is to monitor friction levels, not time in service.

Machines that are properly lubricated require less energy to run. Imagine that reducing grease consumption can lower your energy bills. Machines that consume less electricity run cooler and enjoy longer life cycles.

Finally, by monitoring the condition of your machinery’s lubrication, you are at the same time collecting valuable condition data about the machine itself. Dynamic and static ultrasound data coupled with the 4 condition indicators (RMS, Max RMS, Peak, and Crest Factor) are all indicators of bearing health.

Optimizing lubrication of plant machinery with ultrasound results in a significant reduction in grease consumption. Successful ultrasound programs accelerate the velocity of positive culture change.

Who knew so much good news could come from such a simple shift from calendar to condition based maintenance?

Ultrasound Tip: March 2018

Where Should I Place My Ultrasound Sensor on a Gearbox?

A proven method to assess gearbox condition is to collect a DYNAMIC ultrasound signal. If possible, you want to capture at least 3-5 revolutions of the gearbox. From there, analysis is straightforward. Use UAS2 software to view the signal in the time waveform and spectrum displays. Use the software’s many analysis tools to determine the exact nature of any defects. Just remember these three keys for successful ultrasonic condition monitoring.

  1. Collect the best data you can, using a high quality ultrasonic data collector.
  2. Consistent sensor placement must fundamentally be observed.
  3. Identifying boundaries that impact data transmission is imperative.

Ultrasound is Shy… It Keeps Boundaries

SDT270 detects and measures ultrasound and vibration on gearboxes

Think of ultrasound as the quiet introvert. It prefers to stay in, and rarely mixes well with ultrasounds from other places. We call this “boundary behavior” and it’s another characteristic that makes ultrasound such an attractive condition monitoring technology. Ultrasound signals remain isolated to their source, making it easy to pinpoint defects without interference from other elements of the machine.

Sensor Placement

sdt sensor measures gearboxInspectors tempted to place their ultrasound sensor directly on the gearbox cover, should reconsider. This common mistake affects data integrity. A gasket seals the cover plate to the gearbox housing. The specific acoustic impedance of the gasket material differs greatly from the steel gearbox cover. The change in materials is a boundary barrier through which bashful ultrasound is reluctant to pass. A better option is to place the sensor on a bolt head, which is directly connected to the gearbox housing. The result is crystal clear ultrasound signals for listening, trending, and condition assessment.

Contact Us

For more info about ultrasound and condition monitoring, contact us at

Ultrasound Finds Worn and Misaligned Couplings

Simon is a condition monitoring specialist from a local oil refinery. He contacted my office for advice about predicting flexible coupling failures. Currently, they perform basic vibration analysis on their pumps and motors using an overall meter.  They have some success predicting bearing failures but the same cannot be said for couplings. Several unexpected failures shut them down this year.

Continue reading “Ultrasound Finds Worn and Misaligned Couplings”

Find Condenser Tube Leaks with Ultrasound

Identifying Condenser Tube Leaks with an SDT270 Ultrasound Detector

Case Study – AB Brown Power Plant, Mt. Vernon, Indiana

By Allan Rienstra, SDT Ultrasound Solutions
Data and situational contributions provided by Bill Phipps, Production Manager, Vectren Corporation

Executive Summary

Power Generation facilities aim to run at maximum output during uptime and manage downtime such that it has a minimal effect on efficiency.
Turbine efficiency is negatively impacted by tube leaks in the condenser. Leaks cause contamination of pure water used for steam. When contaminant counts reach alarm states pressure must be lowered reducing output. The turbine continues to run in a low capacity mode until the leaks are found and isolated.
Results Engineers must choose between:

  • Treating the symptoms with a system flush or
  • Fixing the problem by finding leaking tubes and plugging them, thereby removing them from service.

Continue reading “Find Condenser Tube Leaks with Ultrasound”

VIDEO: Acoustic bearing lubrication monitoring using ultrasound

Poorly lubricated bearings are a primary contributor of premature machinery failure. Companies looking to optimize lubrication practices have adopted a conditional approach. By monitoring the friction levels of bearings with ultrasound they can determine when the lubricant has deteriorated and needs replacement. Trending against an establish decibel value, increased friction levels are quickly spotted and alarms triggered. It becomes a standard practice to sort good bearings from those that require the attention of the lubrication technician.

Avoid These 3 Common Mistakes When Lubricating Bearings ->

Hunting for Green Steam


Sustainability and Ultrasound Testing

The Paradox of Sustainability…

When manufacturers face uncertain economic headwinds, the word “Sustainability” can be a paradox.

In a good economy it’s fashionable to invest in green initiatives that promote  environmental sustainability. Reduce that carbon footprint. Conserve energy. Reduce waste. Sustainability under these circumstances paints a picture of responsible big business putting emphasis on the needs of community and planet first.

The paradox occurs when economic conditions turn south. Factories struggle to carve profits from their assets. Green initiatives no longer survive the budget cuts. In fact they are often the first programs to go.

Sustainability is redefined as “doing whatever it takes to keep the doors open.”
Continue reading “Hunting for Green Steam”

Ultrasound and the CBM Journey

Ultrasound CBM
Condition Monitoring with Ultrasound

Look beyond the acronyms and discover the true destination of your CBM journey.

Too philosophical for you? Then ask yourself, “what is the goal of any journey but to arrive at your destination?” Not any destination, YOUR destination. Yes… that means you need to know where you want to go before you leave the start line. Once your destination is locked in, defining the steps along the way becomes much easier.

Still not sure? I can help. Continue reading “Ultrasound and the CBM Journey”