Table of Contents
Advertisement
penetration of the ultrasound through the material resulted by an unstable and there-
fore unreliable measurement.
The surface being measured should be clean and free of any small particulate mat-
ter, rust or scale. The transducer must be placed on a flat and even surface. To get it
clean it might be helpful to use a wire brush or a scraper. In more extreme cases,
rotary sanders or grinding wheels may be used. Care must be taken to prevent sur-
face gouging which inhibits a proper transducer coupling. Extremely rough surfaces
such as the pebble-like finish of cast iron will be measured quite complicated. These
kinds of surfaces comport to the sound beam like frosted glass on light: the beam
becomes diffused and scattered in all directions.
In addition to this, rough surfaces account for an excessive wear of the transducer,
especially when it is "scrubbed" along the surface. Transducers should be inspected
time by time if there are any signs of abrasion.
If the transducer is worn off on one side more than on the other, the sound beam
penetrating the test material may no longer be perpendicular to the surface of the
material. In this case, it is difficult to exactly locate tiny irregularities in the material, as
the focus of the sound beam no longer lies directly beneath the transducer.
4 Operation
4.1 Power on/ off
The instrument is turned on by pressing the
The instrument has got a special memory where all settings are stored even if it was
powered off.
4.2 Zero adjustment
The
key is used to „zero" the instrument. It is just the same way as a mechanical
micrometre is zeroed. If the instrument isn't zeroed correctly, all the measurements
taken may be in error by an initially incorrect value. When the instrument is zeroed,
this fixed error value is measured and automatically corrected for all subsequent
measurements.
The instrument is "zeroed" as follows:
1) The transducer is to be plugged into the instrument in the way that all connectors
are fully engaged.
It has to be checked that the surface of the transducer is clean and free of any de-
bris.
2) The
key has to be pressed.
3) The
key and the
used. The right choice of the sensor is of high importance.
4) A single droplet of ultrasonic couplant is to be applied to the metallic control plate.
TN_US-BA-e-1814
key has to be used to scroll on the sensor model currently
key.
9
Advertisement
Table of Contents
