Manual No. OM5000
Jan X/04 Ver 1.40
51
7. CALIBRATION PROCEDURES
Calibration should be conducted only after properly setting-up the NovaScope initially, in
accordance with Section 6.
7.1 THICKNESS CALIBRATION WITH SAMPLES
a.
Read Sections 8,9, and 10.
b.
Set the THICKNESS/VELOCITY switch in the THICKNESS position.
c.
Select the thickness range to be covered and the units of measurement (English or
Metric) with the RANGE switch.
d.
With the transducer coupled to the calibration sample of the material representing the
upper end of the anticipated thickness range, adjust the front panel CAL control until
the digital display precisely reads that thickness.
e.
Then, couple the transducer to the sample of the material representing the thin end of
the anticipated thickness range and adjust the front panel ZERO control until the
digital display precisely reads that thickness.
f.
Repeat and refine the CAL and ZERO adjustments until the digital display reads both
thicknesses precisely without further adjustment.
g.
Always re-calibrate whenever changing the echo period over which the T-Gate
operates (except where no errors result when gaging on multiples with either delay
line or immersion transducers).
7.2 THICKNESS CALIBRATION WITH VELOCITY
If the ultrasonic velocity for the material to be gaged is accurately known, set the
THICKNESS/VELOCITY switch in the VELOCITY position and adjust it until the known
velocity value appears on the digital display. Be certain that the units of readout selected
(English or Metric) on the RANGE switch agree with the units for velocity. Once the velocity is
entered on the readout, set the same switch to its THICKNESS position for the thickness
gaging.
To accurately utilize this velocity-input feature, it is necessary that the ZERO control has been
properly set previously (to compensate for the inherent time delays in the electronics and
specific transducer/coax cable being used).
Refer to Section 7.3 regarding the NovaScope procedure for determining the velocity of a
given material. Once determined, the velocity value can be used (as described above) to
conveniently thickness-calibrate the NovaScope without the subsequent need for a material