FED-STD-791D
6.1.4 Examine with the 10X magnifier for discoloration, etching, pitting, or other
signs of corrosion. Discard disks with any sign of corrosion.
6.1.5 Store the disks in the desiccator until use. Immerse the brass clips (see 5.3)
in the etching solution for 20 s, and immediately wash successively in cold running
water, distilled water, and acetone. Allow to air dry, and store in the desiccator until
ready for use. Be careful not to touch (with bare hands) the surface that will be in
contact with the steel disks (see Figure 1).
CAUTION:
Acetone is flammable. Use it only in a well ventilated area. Keep all
flames away from this material.
6.3 Remove the disks from the desiccator (being careful not to touch the finished
surface), and using the stirring rod, drip the test sample over the entire polished surface of
each disk.
6.4 Remove the brass clips from the desiccator (being careful not to touch the
area to be in contact with the polished surface of the disks), and place on the disks as
indicated in Figure l so that the center of the clip is in full contact with the disk.
6.5 Place the assemblies in the humidity cabinet for 10 days [relative humidity,
50%; temperature, 27C (79F)].
6.6 Remove the assemblies from the cabinet after 10 days, and using a sharp
pencil, mark an outline of the clips where they were in contact with the polished surface
of the disks. Remove the clips, and wipe the disks clean with lint free cloth.
6.7 Using the 10X magnifier, examine the marked-off area of the disks for
discoloration, etching, pitting, or other signs of corrosion.
6.8 Repeat the test (if the test results are questionable), using new disks and
extending the exposure time in the humidity cabinet to 20 days. Examine the disks and
report as before indicating that the test was repeated.
7. CALCULATION
7.1 This section is not applicable to the test procedure.
8. REPORTING
8.1 Report the oil as failing the test if the test areas of more than one disk show
signs of corrosion, pitting, or other attack. Also report the oil as failing if two are free of
corrosion, but the third shows more than three affected spots. Report the oil as passing if
the condition of the disk is other than these.
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