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Bubble point (first article inspection). |
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|  MIL-F-24666(SH)
4.5 Quality conformance inspection.
Each filter element shall be examined
in accordance with 4.6 and tested in accordance with 4.7.2.
For the pressure
collapse and build-up test specified in 4.7.5 and 4.7.6, sampling filter elements
shall be in accordance with MIL-STD-105, special inspection level S-1.
4.5.1 Noncompliance.
Any filter element which fails the examination of
4.6 and test of 4.7.2 shall be rejected. When the filter element fails to pass
the tests of 4.7.5 and 4.7.6 the entire lot shall be rejected.
All failures of
the tested elements shall be reported immediately by telephone or message.
Full
particulars concerning previous similar failures, the current failures and action
taken to correct the defects shall be submitted to the procuring agency in
writing (see 6.2.2). For purposes of quality conformance inspection, a lot shall
be defined as all filter elements manufactured from one convoluter set-up.
4.6 Examination.
Each element shall be examined to determine conformance
to the requirements of this specification for design, workmanship, markings,
conformance to manufacturer's drawings, and for any visible defects.
4.7 Tests.
4.7.1 Bubble point (first article inspection).
Pre-filter elements
shall be tested to determine the initial bubble point.
The filter element,
containing no fluid, shall be installed in a setup similar to figure 2. The
fluid level shall be maintained at approximately 1/2 -inch above the top of the
filter element. The air pressure, as indicated in inches of water on the mano-
meter, shall be slowly raised by small increments. The element shall be rotated
360 degrees about its longitudinal axis of each increment of air pressure so t-hat
the entire filter area can be observed for the appearance of the first bubble
The area of greatest porosity is determined by observing the first bubble on the
surface of the element; and the manometer reading in inches of water at which
this bubble emits from the element shall be recorded. This test shall be accom-
plished within a period of 10 minutes after immersion in the fixture. The fluid
5F filtered through a 0.45
used shall be Solox 190, or equivalent, at 70
micrometer membrane Millipore filter, or equivalent.
4.7.1.1 Test point values. The minimum allowable initial bubble point
value shall be the lowest initial bubble point of the four first article inspec-
tion elements and shall be determined prior to further testing. This value shall
be indicated on the first article inspection report and filter element drawing
(see 6.2.2).
4.7.2 Bubble point (quality conformance). The filter element, containing
no fluid, shall be installed in a setup similar to figure 2. The fluid level
shall be maintained at approximately l/2-inch above the top of the filter element,
The air pressure shall be preset to 0.1 inch of water less than the minimum ini-
tial bubble point. The filter element shall be rotated 360 degrees about its
longitudinal axis and the entire filter area scanned for the appearance of any
bubbles.
There shall be no bubbles emerging from the filter,
The fluid used
shall be Solox 190, or equivalent, at 70
5F filtered through a 0.45 micro-
meter membrane Millipore filter, or equivalent.
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