How to Choose the Correct Delay Line for Your Dakota PCX Ultrasonic Thickness Gauge

When it comes to measuring thin materials with pinpoint accuracy, the DakotaNDT PCX8 Ultrasonic Precision Thickness Gauges are designed to provide accurate and reliable material thickness measurements on materials as thin as 0.15mm. To do this successfully, they use a single element transducer with a suitable delay line.

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CONTENTS:
0:37 - How do single element transducers work?
1:40 - Which delay line is most suitable for you?
3:04 - How do you change delay lines?
4:28 - For more information
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When triggered by a voltage, single element transducers emit an ultrasound pulse which travels from the transducer into the material aided by ultrasonic couplant, hits the back-wall of the material and echoes back towards the transducer where it is detected. The gauge then uses the speed of the pulse with the time taken between the pulse being emitted and the echo being detected, to calculate the thickness of the material.

However, measuring thin materials means that the ultrasonic signal will return to the transducer incredibly quickly, meaning there’s not always enough time between the pulse leaving the element and the echo returning. This is why when using a DakotaNDT PCX, single element transducers use a delay line to increase the time between the pulse being sent and the echo being received.

DakotaNDT supply two different materials of delay line; acrylic and graphite, and the material you are measuring will affect the material of the delay line you should use. Acrylic delay lines are suitable for measuring on steel, aluminium, titanium, and other thin metals with the gauge in either Interface-Echo or Echo-Echo mode. While thin plastics and other similar materials should be measured using a graphite delay line with the gauge set to Plastic Mode.

There are also different lengths of delay line and the one that is best suited to your application is typically dependent on the thickness and density of the material you’re measuring. For example, a 12mm acrylic delay line is best used on thicker materials and provides greater accuracy on “noisy” materials. In other words, materials that are good conductors of sound.
On the other hand, because it is shorter, a 9mm acrylic delay line provides a greater signal strength, helping you to measure more dense materials which are tougher to penetrate like plastics or lead.

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For more information on delay lines, visit our website:
https://dakotandt.com/en/delay-line.html

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STANDARDS:

EN14127, EN15317