GE Krautkramer USM 35X

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5-72 Issue 01, 04/2005 Krautkramer USM 35X

Operation Evaluation according to the DGS method (only USM 35X S)

• Distance D between the probe and circular disk-

shaped equivalent reflector

• Difference in gain G between various large circular

disk-shaped equivalent reflectors and an infinitely

large backwall

• Size S of the circular disk-shaped equivalent reflec-

tor. The influencing variable S always remains

constant for one curve of the set of curves

The advantage of the DGS method lies in the fact that

you can carry out reproducible evaluations of small

discontinuities. The reproducibility is most of all impor-

tant, for example, whenever you aim to carry out an

acceptance test.

Apart from the influencing variables already mentioned,

there are other factors determining the curve shape:

• sound attenuation

• transfer losses

• amplitude correction value

• probe.

The following probe parameters affect the curve shape:

• element or crystal diameter

• frequency

• delay length

• delay velocity

You can adjust these parameters on the USM 35X S in

such a way that you can use the DGS method with

many different probes and on different materials.

H Note:

Before setting the DGS function, the instrument must

first be calibrated because all functions affecting the

DGS evaluation mode (MTLVEL, P-DELAY, DAMPING,

POWER, FINE G, FREQU, RECTIFY) can no longer be

changed after the reference echo has been recorded.

Please also refer to chapter 5.7

Calibrating the

USM 35X

on this subject.