How To Measure With The Dgs - Epson USN 52R Operating Manual

Introduction

1.1 How to measure with the DGS

The DGS option (Distance - Gain - Size) enables you to
compare the reflecting power of a natural flaw in the
test object with the reflecting power of a theoretical flaw
(disk-shaped reflector) at the same depth.
Attention:
You are comparing the reflecting power of a natural flaw
with that of a theoretical flaw (= disk-shaped reflector)
at the same depth. No definite conclusions with regard
to the natural flaw (roughness, oblique
position, etc.) are permitted.
The basis of this comparison of the reflecting powers is
the so-called DGS diagram. This diagram consists of a
set of curves showing the interrelationship of three in-
fluencing factors:
• Distance D between probe and disk-shaped reflector,
• Gain difference G between disk-shaped reflectors of
different sizes and an infinitely large backwall,
• Size S of the disk-shaped reflector.
DGS-6
The factor S is always constant for one curve of the set
of curves.
The following illustrates the general DGS diagram. This
diagram is standardized with regard to the near-field
length and the element diameter:
Issue 02, 03/99
How to measure with the DGS
Krautkramer USN 52R/USN 52L Option DGS