WELCOME Ultrasonic Inspection A brief overview of ultrasonic

WELCOME! Ultrasonic Inspection A brief overview of ultrasonic inspection principles, applications, & techniques. Presented by Superior Signal Company, Inc. Copyright 2000, Superior Signal Company, Inc. Not to be reproduced in any way without written permission from Superior Signal Company, Inc. If you are not currently viewing this as a full screen presentation, click the small icon which looks like the sample to the left. It is located at the lower left of your screen (above the start button). Then Click here to Begin

A few Instructions Use the following icons to move through the presentation. . . Move ahead 1 page. Move back 1 page. Play Sound Hit ESCAPE at any time to exit the presentation. Click when ready. . .

What is Ultrasound? Sound frequencies above 20 k. Hz are considered Ultrasonic. These are frequencies above the human range of hearing. It doesn’t matter how loud, or how strong the amplitude of a particular ultrasound, our unaided human ear can NOT hear it Click when ready. . . Hit ESCAPE at any time to exit the presentation.

High Frequency Ultrasound Comes from. . . F riction A rcing (In moving equipment) (In electrical connections) T urbulence (In leaking systems) Although there are frequently sonic sounds also associated with faults/leaks, we can not simply use our ears to hear them because they are masked by high ambient noise levels. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Important Characteristics of Ultrasound It Does not travel as far as sonic sound. Sounds waves are more localized, easier to trace to their source. It Does not bend or penetrate as easily. Sounds waves do not travel well around corners or through objects. It Does reflect (echo). Ultrasounds will bounce or reflect off surfaces, however reflections are lower in amplitude than the original signal. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Sound does not travel well from one medium to another. (liquid to gas, gas to solid, etc. ) Example; It is difficult for someone only a few inches underwater to hear what is going on at the surface. This is the reason specific sensors are designed for detection within a particular medium. (Contact, Airborne or Liquid) Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Detection Methods REMEMBER: Sound does not travel well from one medium to another. (liquid to gas, gas to solid, etc. ) This is why different pick up devices, or sensors, are used for the specific job at hand. • Airborne Sensor Use to detect sounds which are created within air, and travel through the air. • Pressure Leaks • Vacuum Leaks • External Valve Leaks • External Hydraulic Leaks • Electrical Arcing • Contact Sensor Use to detect sounds which are created within solids, and travel through solids. • Defective Steam Traps • Worn Bearings/Gears • Internal Valve Leaks • Internal Hydraulic Leaks Click when ready. . .

Ultrasonic Instruments Detect and Convert High (Ultrasonic) Frequency Sound To low (Sonic) Frequency Sounds must be translated, or converted to lower /audible frequencies in order to be heard by the user, or analyzed. Click when ready. . .

There are two electronic processes used in ultrasonic detectors to select and convert high frequency ultrasound to lower, audible frequencies. Heterodyne The word is from the Greek, meaning Different Waves. DND This is an acronym for Dynamic Noise Discrimination. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Frequency Tuning (Heterodyne) When using a heterodyne type detector you have a limited window of sound that you can hear at any one time. It is like a radio in a sense that you can only tune to, or hear one frequency (radio station) at a time. When using an instrument that allows you to “tune”, you are basically adjusting a vertical window up and down the detection range of the instrument (left and right in the example above). The width of this window depends on the instrument, but it is generally not more than a few k. Hz wide. A disadvantage to heterodyning is that if a key signal is outside of this window, it will not be detected. Click when ready. . .

Frequency Selection (DND) Low Sensitivity High Sensitivity When adjusting the sensitivity of a “DND” type detector, think of it as moving a horizontal threshold up and down over the detection range of the instrument. As you lower the sensitivity only the signals of the greatest amplitude will be translated, while all sounds will be translated when using a high sensitivity setting. A detected sound will not trigger the translation process until the amplitude crosses this threshold. Once it does, it does not matter where the original frequency came from, it will be translated to an audible signal. This is the advantage to DND. No tuning is involved! Click when ready. . .

Technology Comparison • Heterodyne • Close to real sound translation • Best for contact applications • Best for using with analyzers • Limited frequency range • May miss signals if not tuned properly • DND • “Automatic” Tuning • Best for air leaks, especially in very loud areas. • Very simple to use. • Sound does not maintain true “signature” • Can not use with analyzer Click when ready. . .

Application; Air Leaks When a pressurized gas leaks from an orifice, it is forced into turbulence where the molecules collide and rub into each other. It are these collisions that create ultrasonic tones which can be detected using an ultrasonic leak detector. Photo reference; An Album of Fluid Motion. Van Dyke, Parabolic Press Click when ready. . .

Finding leaks with ultrasound depends on. . . n How much turbulence is present, which depends on. . . – Size of leak – Shape of leak – Material composition of leak • Flexible material will not produce as much turbulence as more solid material. – Pressure behind the leak. – Atmospheric Conditions Click when ready. . .

Use Ultrasound to Minimize Leakage! Do your compressors run between shifts? Do you have difficulty maintaining optimum pressures? Have you come to rely on a backup compressor for routine demand? • Reduce power consumption • Save Money • Reduce Chance of Failure Click when ready. . .

Sound of an Air Leak This air leak was found on the main air outlet pipe of a noisy compressor. Listen to the difference between the background noise and the leak sound as the instrument moves back and forth across the direction of the leak. Heterodyne type detector DND type detector Click to hear. Click when ready. . .

Air is NOT Free! This chart estimates the financial impact of 38 leaks of various sizes within a 6 month period. Click when ready. . .

Ultrasonic Leak Detection n Ultrasound is the only technology that will detect ANY type of gas, including systems under VACUUM! n Unlike gas “sniffers” It is not affected by wind, contaminants or concentrations of gas in the air. n Detect leaks in areas NOT pressurized (Using Sound Generator). Click when ready. . .

Application; Steam Traps Detect ultrasonic frequency of internal turbulent flow. What is a steam trap? Simply stated, a steam trap is a mechanical device designed to remove condensate (water) from the system while retaining (trapping) the steam. Why are they needed? • Efficiency; Keep system HOT, return water to boiler. • Eliminate Waterhammer Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Why test them? Steam Traps are generally located at low points in the system, a natural collecting point for dirt, rust, and other contaminants. n Steam Traps Fail – Open • Pass live steam which is costly to produce. – Closed • Condensate will collect. Click when ready. . .

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One Leaking Trap. . . (5/64 in. orifice @ 150 psig) • Loses 27 lb/hr. or… 226, 800 lbs. of steam per year! Cost to produce? . . . • 12 tons of coal ($679. 00) • 2, 500 gal. of fuel oil ($1392. 00) • 314, 000 cu. ft. of natural gas ($1272. 00) A typical petrochemical plant will use 5000 steam traps. In plants with no previous trap testing generally 30% are leaking. How many traps are leaking in your facility? Click when ready. . . Ref: Assessing the Impact of Energy Losses in Steam Systems, Plant Engineering, July 10, 1995

Trap Sounds n Continuous flow type traps require more of a trained ear to detect leakage by listening only. Compare meter readings with a known “good” trap. n Intermittent purge traps (inverted bucket) usually fail open. Listen for rushing sound. Good Inverted Bucket Trap Bad Inverted Bucket Trap Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Application; Valves Detect ultrasonic frequency of internal turbulent flow. Why Test them? Case : A pipeline where the contents are various gases; oxygen, carbon dioxide, compressed air, and nitrogen. Pressure differential across the valves is approximately 60 psi. Valve leakage causes non-conformance to the required purity standards, making the final product unusable. Solution: A monthly program of ultrasonic detection was successful in determining which valves were leaking and how extensive the leaks were. The test consisted of taking a reading upstream and downstream of the valve under test. Leaking valves showed higher ultrasound in the turbulent area downstream of the valve. Result: Maintenance time and costs formerly spent on rebuilding sound valves were saved and product purity was significantly improved. Click when ready. . .

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Application; Electrical Discharge Corona Arc Use ultrasound to hear what you can’t see in switchgear, breakers, distribution lines, insulators, and transformers. Click when ready. . .

Arcing / Corona Ultrasound compliments thermography … n Detect problems which may be masked by ambient heat. n Onset of Corona does not cause temperature change. n Ultrasound does not require opening of electrical cabinets. n It is easy, fast and inexpensive. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Application; Bearings & Gears As bearings and gears wear, ultrasonic signatures present themselves. Listen For. . . n n n Click to hear. n Lubrication break down Impact Scraping / Grinding Friction Click when ready. . .

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There are two types of trending used with ultrasonic inspection. Comparative; Compares to other similar machines. Intensity Example; If you have a group of 5 pump motors each performing the same job under the same conditions, inconsistently high ultrasonic readings will indicate a defect, or the onset of failure. #1 #2 #3 #4 #5 Pump Motor # The condition of motor #4 may be obvious, and possibly even diagnosed simply by listening. Click when ready. . .

The other type of trending typically used with ultrasonic inspection is. . . Historical; Looks for inconsistencies over a period of Intensity time… Example; If you had looked specifically at readings taken on pump #4 (from the previous page), they may look like this. . . Date The progressive increase in readings could be due to lubrication breakdown, or wear. Lubricate and retest. If readings are again elevated after a short period of time, the Click when ready. . . bearing is on the road to failure.

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Spectrum Analysis For more detailed analysis, ultrasonic translations can be output (through the headset jack) to typical vibration / spectrum analyzers for storage and later comparisons. This reading was taken using a heterodyne type ultrasonic detector tuned to 38. 5 k. Hz, output to a common vibration analyzer. The frequency range shown is 10 Hz to 1100 Hz (or 1. 1 k. Hz). Remember, these are not actual frequencies, they are TRANSLATED from the ultrasonic range. You must know precisely where the unit was tuned (in this case 38. 5 k. Hz) to determine the actual frequency. The peak shown here at 70 Hz has come from an original signal of either 39. 2 k. Hz, or 37. 8 k. Hz, depending on whether it was above or below the tuned frequency. Click when ready. . .

Spectrum Analysis Inexpensive software packages are also available. Here the sounds were recorded with a cassette and played back into a PC. This graph shows the low level of ultrasound from the motor side bearing of a high-speed overhung cantilever fan. The sound is barely audible. This trace shows the fan side bearing, approximately one foot away, on the same fan. The excessive ultrasound was due to a bent fan shaft. Click to hear! Click when ready. . .

What is the difference between Sound and Vibration? VIBRATION: Any mechanical oscillatory motion of a machine member. SOUND: Vibration of air molecules (airborne sound), or molecules in solids (solid borne sound). Sound is the precursor to vibration. It is vibration that is too fast, and with an amplitude too small to move “large” masses. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Why use Ultrasound on bearings? n As a compliment to vibration analysis. – Test more points in less time. • Little training needed, less equipment to carry. • Allows you to perform PM on less critical equipment – Increase window of prediction. • May see elevated ultrasonic levels before changes in vibration are present. – Effective at fault detection on slow speed equipment. – Help determine lubrication intervals and amounts. • Listen to sound levels decrease as lubricant is induced. n As a stand alone program. – – Capable of establishing basic trends and alarm levels. Use your ear and instrument readings to confirm problems. Inexpensive, and easy to use; little training required. Excellent start for those implementing first PM program. • Very versatile Click when ready. . .

Accu. Trak Ultrasonic Inspection Instruments Product line overview n Model VPE-1000 – Low cost digital n Model VPE-2000 – Advanced Digital n Model VPX-WR – The ultimate air leak detector featuring “DND” technology n Combo Package – Offers the best of everything Superior Signal has been providing excellent products at affordable prices for over 40 years. We are the only company offering true innovations in ultrasonic inspection technology. To prove it, we hold 4 of the most recently issued patents in the field. Click when ready. . . Hit ESCAPE at any time to exit the presentation.

Accu. Trak Model VPE-1000 When powerful performance is needed and budgets are limited, choose the versatile VPE-1000. It is the first low cost digital ultrasonic detector offering extraordinary features at a fraction of the cost of other ultrasonic instruments! • Digital LED indicators (Alphanumeric and Bargraph) • Digital Peak Hold • Separate Volume & Sensitivity • Dual Sensors (no changing heads) Perfect for hospitals, schools, hotels, and other large institutional or light industrial environments. Excellent for steam trap testing! Click when ready. . .

Accu. Trak Model VPE-2000 First in digital ultrasonics the VPE-2000 is rich in features, yet remains compact and easy to use. In addition to everything offered on the VPE-1000, the VPE-2000 also offers selectable frequency modes, including sonic mode. • Digital LED indicators (Alphanumeric and Bargraph) • Digital Peak Hold • Digitally tuned for maximum repeatability • Separate Volume & Sensitivity • Dual Sensors (no changing heads) • 5 sensor/frequency modes, including SONIC • Includes variety of accessories (probe extensions & more) Click when ready. . .

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Accu. Trak Model VPX-WR n n Offers patented “DND” technology which tunes itself automatically to dominant leak sounds. Absolutely the best for finding leaks fast, especially in loud environments. Sophisticated inside, Simple outside. Most durable unit available, hard anodized aluminum shell, and completely waterproof. Click when ready. . .

Accu. Trak Combo Offer Get the best of Both, Two units, One Great Price! Allows you to have two people, with two instruments performing numerous tasks. Combo offer includes one Model VPX-WR and one Model VPE-2000; Two state of the art instruments for the price of one analog “gun” type detector. Click when ready. . .

Congratulations, You’ve reached the end of the Program! Hit Escape to exit the program now. For more information on ultrasonic inspection contact. . . Superior Signal Company P. O. Box 96 Spotswood, NJ 08884 1 -800 -945 -TEST, or (732) 251 -0800 www. Superior. Signal. com