Setting Up Gauge - Elcometer PG70 Operating Instructions Manual

5 SETTING UP GAUGE

As a delay line transducer should be used with these gauges, zeroing of the gauges is not necessary.
5.1 CALIBRATION
In order for the gauge to make accurate measurements, it must be set to the correct sound-velocity for the
material being measured.
Different types of material have different sound-velocities. For example, the velocity of sound through steel
is 5918 m/s (about 0.233 in/µs) and the velocity of sound through aluminium is 6350 m/s (about 0.248 in/µs).
Setting the calibration is crucial for the gauge to function and the procedure should be carried out after every
probe zero and when the material type is changed.
There are two methods of calibrating your gauge:
K
NOWN THICKNESS CALIBRATION
K
NOWN VELOCITY CALIBRATION
the gauge.
Note: Known thickness calibration must be performed on material with the paint or coating removed. Failure
to remove the paint or coating prior to calibration will result in a multi-material velocity calculation that may
be different from the actual material velocity intended to be measured.
5.1.1 Known thickness calibration
This procedure requires a sample piece of the material to be measured, the exact thickness of which is
known, having been measured by some other means e.g with a caliper or micrometer.
1. Apply couplant to the sample piece.
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: This is the simplest and most commonly used calibration procedure.
: The sound-velocity of the material being measured is entered directly into