User's Manual
MIL-PRF-46374G
16
4.6.5.14.1 or 4.6.5.14.2 as applicable, with the stem parallel to the direction of the field. Upon
completion and removal from the field, the watch shall be rated by a precision type rate recorder
to determine compliance with 3.5.7.
4.6.5.14.1 Magnetism - type I. Watches shall be subjected to the field specified in 3.5.7, with the
field on for 3 seconds and off for 3 seconds. This cycle shall be repeated 10 times.
4.6.5.14.2 Magnetism - types II and III. Watches shall be subjected to the field specified in 3.5.7,
for 10 minutes.
4.6.5.15 Dark viewing. A dark room shall be used to represent total darkness when conducting
the visual examination under the conditions and distance specified in 3.5.8 to determine
compliance therewith. Watches shall be in the dark room for at least 8 hours prior to conducting
examinations. Individual(s) performing the test shall be acclimated to the dark room for a
minimum of 20 minutes prior to conducting the test. There shall be no intervention required, for
example, by pushing a button, on the part of the individual in order to read the watch. This test
shall be performed no sooner than 60 days after assembly of watches.
4.6.5.16 Isochronism (class 4 only). This test shall be conducted concurrently with 4.6.5.17
(see 3.5.9).
4.6.5.16.1 Type I. In the position and at the temperature specified in 3.5.9, the watch shall be
fully wound and operated for 4 hours. The watch shall again be fully wound and the rate
recorded while fully wound and after 4 hours of operation. The rates shall again be recorded at
the 20th and 24th hour. The difference in uniformity of rate between the 4-hour periods shall not
exceed 10 seconds.
4.6.5.16.2 Types II and III. This test shall vary from 4.6.5.17 in that the error shall be
determined at 6-hour intervals. The difference of error recorded between each 6-hour period shall
not exceed 5 seconds.
4.6.5.17 Accuracy. During the conditioning period, the running watches shall be subjected to the
test temperatures of table III for at least 4 hours prior to the test. Daily rates shall be recorded for
a period of 3 days in each position and the mean daily rate determined therefrom. The watches
shall be rejected if the mean daily rate exceeds the requirements of 3.5.10. The mechanical type
watches shall be wound at the beginning of each test and each 24 hours thereafter for the duration
of the tests (see 4.6.5.16).
4.6.5.18 Altitude - types II and III. Watches shall be subjected to the operating environment
specified in 3.5.12.
4.6.5.19 Salt fog - types II and III. Watches shall be subjected to the operating environment
specified in 3.5.13. Upon completion of exposure to salt fog, the watches shall be rinsed and
allowed to dry for 48 hours prior to examination.