MIL-PRF-87257B
4.4.5
Particulate contamination
4.4.5.1 Particle count
Particle count shall be measured by the use of an automatic particle counter employing the light
interruption principle. The automatic counter shall count particles to the limits specified in
table II. The operating directions in the manual for the respective instrument shall be used.
4.4.5.2 Gravimetric
A gravimetric determination shall be made in accordance with ASTM D 4898 with the following
additional requirements:
a. Exposure of the filter to open air shall be minimized. While in the petri dish, the lid shall
remain on at all times.
b. Select two white, 0.45-micron, polypropylene membrane filters (such as Pall-Gelman,
GH-Polypro). Place each filter in a clean petri dish, cover, and put both dishes in a desiccator
for at least 15 minutes.
c. Remove petri dishes containing filters from the desiccator. Take a filter from its petri
dish, pass it through an ionizer for 10 seconds, and then weigh it. After weighing, immediately
return the filter to its petri dish. Repeat with the second filter.
d. After filtering and drying on a filtration apparatus, dry the filters in their covered petri
dishes for 15 minutes in a 75°C oven. Do not use other drying methods. Remove closed petri
dish from the oven; allow filters to equilibrate to ambient room conditions in a desiccator for 15
minutes before weighing.
4.4.6 Color of finished fluid
The color of the hydraulic fluid shall be compared with a standard sample prepared by adding 1
part of dye "Oil red 235" (see 6.1.4) to 10,000 parts of an oil not darker than ASTM D 1500 color
number 1.0.
5.
PACKAGING
5.1 Packaging
For acquisition purposes, the packaging requirements shall be as specified in the contract or
order (see 6.2). When actual packaging is to be performed by DoD personnel, these personnel
need to contact the responsible packaging activity to ascertain requisite packaging
requirements. Packaging requirements are maintained by the Inventory Control Point's
packaging activity with the Military Department or Defense Agency, or within the Military
Department's Systems Command. Packaging data retrieval is available from the managing
Military Department's or Defense Agency's automated packaging files, CD-ROM products, or by
contacting the responsible packaging activity.
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