FED-STD-791D
6.4.2 Atomization. The conditions maintained in all parts of the exposure zone
shall be such that a suitable receptacle placed at any point in the exposure zone will
collect from 0.5 to 3 mL of solution per hour for each 80 square cm of horizontal
collecting area (10-cm diameter) based on an average run of at least 16 hours. The
solution thus collected shall have a sodium chloride content of 4.5 to 5.5% for the 5-
percent solution (specific gravity 1.027 to 1.041 when measured at 35 1C [95
2F]) or a sodium chloride content of 18 to 22% for the 20-percent solution (specific
gravity 1.126 to 1.157 when measured at 35 1C [95 2F]). At least two clean
fog-collecting receptacles shall be used, one placed nearest to any nozzle and one farthest
from all nozzles. Receptacles shall be fastened so that they are not shielded by
specimens and so that no drops of solution from specimens or other sources will be
collected.
NOTE 3:
When using nozzles made of material nonreactive to the salt solution,
suitable atomization has been obtained in boxes having a volume less than
0.34 m3 (12 ft3) with the nozzle pressure 82 to 124 gage kPa (12 to 18
psig) with the orifices of 0.05 to 0.08 cm, and with the atomization of
approximately 3 L (3 qt) of salt solution per 0.28 m3 (10 ft3 of box volume
per 24 h). When using large size boxes having a volume considerably in
excess of 0.34 m3 (12 ft3), the above conditions may have to be modified
to meet the requirements for the operating conditions.
6.4.3 Length of test. The length of the salt spray test shall be as required by the
product specification. The test shall be run continuously for the specified test period, or
until a definite indication of failure is observed, with interruption only for adjustment of
the apparatus and for inspection of the test panels.
6.5 At the end of the test, the test panels shall be examined immediately to
determine compliance with the standards of acceptability given in the product
specification. If necessary for examination purposes, the test panels may be washed
gently or dipped in running water not warmer than 38C (100F) and brushed lightly.
7. CALCULATIONS
7.1 This section is not applicable to the test procedure.
8. REPORTING
8.1 Report the number of specimens tested and the number of passing or failing
results.
9. PRECISION
9.1 Precision data have not been developed for this method.
Method Prepared by:
Army - ME - 1986
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