DM4E, DM4, DM4 DL Operating Manual
Page 11
2.0 Operation
Figure 2-9
2.7 Calibration to a Known Velocity
NOTE:
2-PT calibration mode must be set to OFF.
If you know the velocity of sound of the material to be measured,
the instrument can be calibrated to the known velocity without
the use of a calibration standard. However, the calibration should
always be verified by measuring a known thickness (or calibra-
tion standard) of the same material and velocity as the material
to be measured.
To calibrate to a known velocity, press
until VEL illuminates.
The current velocity setting is displayed, as illustrated in
Figure 2-9.
Press
to enable calibration mode.
DM4E, DM4, DM4 DL Operating Manual
Figure 2-10
With the CAL indicator flashing, use and to set the
displayed velocity to that of the material under test.
Figure 2-10 shows how the display would appear for a calibra-
tion of .2328 inches per microsecond.
Press
again to exit velocity calibration mode and return to
THK mode.
Table 2-1, below, shows typical sound velocities for some com-
mon materials. Because processing, exact composition, and tem-
perature affect velocity, the values may not precisely match the
velocity in the material to be measured.
Material in/µs m/s Material in/µs m/s
Aluminum .2500 6300 Nylon .1000 2500
Brass .1700 4300 Phenolic .0560 1400
Cadmium .1100 2800 Platinum .1600 4100
Cast Iron .1800 4600 Plexiglas .1100 2800
Copper .1800 4600 Polyethylene .0700 1800
Epoxy Resin .1100 2800 Polystyrene .0930 2400
Glass (Crown) .2200 5600 Polyurethane .0700 1800
Glass (Window) .2700 6800 Porcelain .2200 5600
Gold .1300 3300 Rubber (Butyl) .0730 1900
Inconel .2200 5600 Rubber (Vulc.) .0900 2300
Lead .0850 2200 Silver .1400 3600
Magnesium .2300 5800 Steel .2300 5800
Manganese .1800 4600 Tin .1300 3300
Molybdenum .2500 6300 Titanium .2400 6100
Monel .2100 5300 Tungsten .2100 5300
Neoprene .0630 1600 Zinc .1600 4100
Nickel .2200 5600 Zircaloy 2 .1900 4700
Table 2-1: Typical Sound Velocities in Various Materials (Longitudinal Wave)
NOTE: This information is provided for the convenience of the user and Agfa NDT Inc. assumes no responsibility for inaccura-
cies. Actual velocities depend on exact composition, temperature, and processing of each material.
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