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Table 1-4. Ring Specimen Indications | Up
TM-1-1500-335-23 Nondestructive Inspection Methods Manual | Next
Figure 1-9a. Establishing a Field Indicator Reference Standard |
T.O. 33B-1-1
AC amperage variations exceeding ±10% at maximum rated unit output SHALL necessitate location the
source of the difficulty and corrective action taken. The ammeter/shunt SHALL be calibrated as prescribed
in T.O. 33K-1-100-1.
1.6.12
Quick Break Tester.
Check SHALL be accomplished to insure the presence of accurate decay rate sufficient for quick break
magnetization. The quick break tester is authorized in TA-455. Operation fo the quick break tester SHALL
be accomplished according to the commercial manufacturer’s operating instructions. Test failure SHALL
necessitate locating the source of the difficulty and corrective action taken. The quick break check SHALL be
performed at least once each 60 calendar days.
1.6.13
Establishing a Field Indicator Reference Standard. (See Figure 1-9a.)
a.
Place a small bar magnet (approximately 1 by 1/2 inch) vertically near the bottom of an 8 1/2- by 11-
inch sheet of paper and trace around the magnet with a marker. (It does not matter which pole of the
magnet is up.)
b.
Place a new field indicator at the top of the paper with the bottom of the indicator above and in line
with one pole of the magnet.
c.
Slowly move the new field indicator toward the magnet until a half-scale meter reading is obtained.
(If the south pole of the magnet is up, the meter needle will def lect to the right.)
d.
Mark the location of this field indicator by tracing along the bottom of the indicator with a marker.
Label the line with a unique letter.
e.
Repeat steps b, c and d with all remaining new indicators in the NDI shop inventory. Use the same
magnet at the same orientation.
f.
From among the group of new field indicators tested, select the one that gave a half-scale reading at
the most common position marked on the sheet of paper.
g.
Label the selected field indicator as the reference standard.
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