Ultrasound pinpoints compressed air leaks

For more than 30 years, ultrasound technology has been the preferred diagnostic technology of maintenance departments throughout the world.

By Alan S. Bandes, UE Systems, Inc. May 1, 2009

For more than 30 years, ultrasound technology has been the preferred diagnostic technology of maintenance departments throughout the world due to its simplicity and reliability as well as its ability to save plants hundreds of thousands of dollars in production and energy waste.

In this time, hundreds of case studies have documented how ultrasonic detectors pinpoint leaks in steam traps and valves, detect bearing wear, and identify arcing, tracking and corona in electrical equipment. Virtually every industry has profited from early detection of potential serious problems while reducing their energy consumption and carbon footprint along the way.

The effectiveness of ultrasonic

Most leakage problems produce a broad range of sound. The high-frequency ultrasonic components of these sounds are extremely short wave signals that tend to be fairly directional. Therefore it is easy to isolate these signals from background plant noises and to detect their exact location.

Airborne ultrasound instruments, often referred to as “ultrasonic translators,” provide information in two ways: qualitatively through the ability to “hear” ultrasounds through a noise-isolating headphone and quantitatively via incremental readings, such as decibels on a meter.

Although the ability to gauge intensity and view sonic patterns is important, it is equally essential to be able to “hear” the ultrasounds produced by various equipment. That is precisely what makes these instruments so popular. They allow inspectors to confirm a diagnosis on the spot by being able to clearly discriminate among various equipment sounds.

When routinely inspecting compressed air and steam trap systems, ultrasound technology is among the most effective and efficient ways to ensure detection of leaks, helping increase production and reduce energy waste — controlling your carbon footprint.

Easy-to-use instruments

Today’s airborne ultrasound translators are portable and relatively easy to use. They generally consist of a handheld unit with headphones, a meter or display panel, a sensitivity/volume adjustment, and (most often) interchangeable modules used in either a scanning or contact mode. Some instruments have the ability to adjust the frequency response from between 20 kHz to 100 kHz. An ultrasonic transmitter, called a tone generator, is often included.

Many of these features are useful in helping a user adapt to a specific test situation. As an example, should a low-level leak occur in a water valve, the frequency tuning can be adjusted to help a user tune into and hear the trickle of the water leak.

Digital instruments are supported by software that is used to report leak survey results. Some software calculates the survey savings as well as related carbon footprint gas reduction for reporting purposes. For leak management purposes the reports generated by the software provides information on leaks found and, more importantly, leaks repaired.

Leak detection

According to the U.S Department of Energy, compressed air is the most costly utility in plants today. When a manufacturer’s utility bills run into the millions of dollars annually, management is wise to keep a close eye on wasted energy. This is why many facility managers now have a compressed air program with

Ultrasonics as their key weapon to fight air leaks.

Here are some recommended steps to use in a compressed air survey:

Walk through the test area. While walking, pay attention to obvious problems such as loud leaks that can be spotted and tagged without the aid of an ultrasonic detector. Observe misuse of air such as valves left wide open, rags placed over pipes to reduce the noise level of large leaks, unattended machines left on with air blowing all over the place.

As you walk, try to determine the best route for inspection.

For consistency, start at the compressor/supply side and work your way to the use side.

When you begin your inspection, create a series of inspection “zones”. This will help organize your approach and prevent the possibility of overlooking a section and missing some leaks.

Tag all leaks. The tag will make it easy to spot the leaks for repair.

Test all leaks after they have been repaired. Sometimes leaks can be fixed and new ones created inadvertently.

Calculate your savings using cfm charts, air leak formulas and software.

Report your results.

The use of ultrasound technology helps detect minute leads in compressed air and other systems.

Author Information

Alan Bandes is vice president of U.E. Systems, Inc. He can be contacted at abandes@att.net or by visiting www.uesystems.com .