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CHAPTER FIVE
MAKING MEASUREMENTS
The steps involved in making measurements are detailed in this section. The
following sections outline how to setup and prepare your
ZX-1
for field use.
A manual zero must always be performed. A manual probe zero is performed using
the reference disk (battery disk) attached to the top of the instrument. The zero
compensates for variations of the transducer. Once the probe zero is completed, the
sound velocity must be determined to convert the transit time to a physical length.
The sound velocity can be selected from the material chart in the manual, or
manually adjusted using a single, or multiple, known reference point(s) until the
ZX-1
correctly measuring the reference point(s). The later will result in greater precision
overall. To enter a common velocity from a table of velocities, look up the material on
the chart in the appendix of this manual. Refer to the section below on Material
Calibration for instructions on manually adjusting the velocity using a reference
point(s)/standard(s). To determine the velocity of a single sample, refer to the
Material Calibration section on page 14.
5.1 Probe zero
Setting the zero point of the
ZX-1
is important for the same reason that setting the
zero on a mechanical micrometer is important. It must be done prior to calibration,
and should be done throughout the day to account for any temperature changes in
the probe. If the
ZX-1
is not zeroed correctly, all the measurements taken may be in
error by some fixed value.
The “on block” zero procedure is outlined below:
Performing a Manual Probe Zero (On Block)
Note:
The probe zero disk (battery cap) is located on the top of the gauge, and
used as the zero standard.
1) Apply a drop of couplant on the transducer and place the transducer in
steady contact with the disk (battery cover) located at the top of the unit to
obtain a measurement.
