MIL-DTL-3971F
3.5.7 Salt spray. Meters shall operate for at least 1 hour, be accurate within ± 1 percent of
actual elapsed time and show no evidence of damage to the finish after being subjected to the salt
atmosphere test of 4.4.6.10.
3.5.8 Power supply tolerance. The meter shall not be damaged, operate for at least 1 hour,
and be accurate within ± 1 percent of actual elapsed time when subjected to the power supply
tolerance test of 4.4.6.11. The meter is exempt from being accurate during the test but shall
resume proper operation when returned to the specified nominal.
3.5.9 Water resistance. Meters shall be capable of rejecting the entry of water when
subjected to the water resistance test of 4.4.6.12.
3.5.10 Long term accuracy. Meters shall be capable of operating continuously for 2500
hours and be accurate within ± 1 percent when subjected to the long term accuracy test of
4.4.6.13.
3.6 Identification marking. The identification marking shall be as specified in figure 1.
Type
Grade
Part No.
Date
Frequency and Voltage
Mfr's Name
Federal Stock No.
Contract or Purchase Order No.
FIGURE 1. Identification marking.
Note: The part number, date, frequency and voltage, manufacturer's name, federal stock number
and contract or purchase order number may be applied without their descriptive titles.
Identification markings which appear on the dial need not be duplicated on the case.
3.6.1 Application. The marking shall be applied on the side or rear of the case and shall be
legible after withstanding the test procedures of 4.4.6.8, 4.4.6.9 and 4.4.6.10.
3.6.2 Acceptance date. The marking shall include the date of acceptance of the meter by the
Government. The marking for the month shall be the first three letters and the marking for the
year shall be the last two numbers, e.g., December 2000 is Dec 00.
3.7 Workmanship. Workmanship shall be of a quality consistent with the highest
commercial production standards and practices. The meters shall be free of loose components,
rust, scratches, burrs, sharp edges, chips, and unnecessary oil or foreign materials.
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