DMTA-10040-01EN, Rev. E, February 2018
Chapter 5216
The subtracting frequency should be at least half of the prime frequency. However,
since the NORTEC 600 allows fully independent frequencies, the best results are
obtained with a ratio of 4:1 between the highest and lowest frequency. This section’s
procedure has been prepared with frequency 1 as the highest frequency, though the
NORTEC 600 will function equally as well with frequency 2 as the highest frequency.
Inspection materials are shown in Figure 5-135 on page 216.
Figure 5‑135 Materials—dual frequency for heat exchanger tubing
The following products are used in this procedure:
• Eddy current bobbin probe for heat exchanger tubing: absolute/differential,
14.8 mm (0.583 in.) diameter, 15 kHz center frequency, 20 m (65.6 ft) cable;
P/N: TEA-148-015-N05 [U8282109]
Cable—part 3 of
foot switch
Auxiliary absolute
tube adaptor
EC bobbin probe
Foot switch—part 1
Connector—part 4
of foot switch
Cable—part 2 of foot switch
Calibration tube with ring
Top of instrument
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