MIL-F -246 66(SH)
4.7.3 Coalescer protection
P~e-filter elements shall be installed in the
applicable filter case and tested in series with referee coalescer elements as
specified in MIL-F-15618 and qualified to MIL-F-8901.
Testing shall be in
accordance with the following test plan.
All pre-filter elements shall be tested for performance in and
resistance to water by use of a testing apparatus similar to
Components shall conform to MIL-F-8901.
F-76 fuel in accordance with MIL-F-16884 shall be circulated
through the system at a flow rate equal to the rated flow of the
elements to be tested (pre-filter and coalescer).
The test fuel shall be cleaned by filtering to a maximum level of
Distilled water shall be continuously injected at a rate of 2.0
percent to 3.0 percent by volume of the total fuel flow
ACFTD shall be added to the fuel tank at an average rate of 10
The contaminant shall be distributed uniformly by mixing the
fuel with an agitator for 30 minutes. The fuel tank shall be
continuously agitated during tests.
The temperature of the test fuel shall be maintained at 75 to
Total water content shall be determined by Karl Fischer method.
The free water is defined as the difference between the total
water content of the effluent fuel sample minus the saturation
value of the uncontaminated test fuel at the same temperature
as the effluent sample.
188.8.131.52 Test procedure . Tests shall be run at the rated flow of the pre-
filter element until the pre-filter fails or the coalescer fails or a maximum
of 4 hours, whichever comes first. Record pressure differential in
differential across pre- filter and coalescer at 10 minute intervals.
coalescer effluent fuel sample at 10 minute intervals for free water content.
differential vs. time for pre-filter and coalescer, and
Record values of
effluent free water vs. time. Flow to coalesce shall be at rated flow of
the coalescer as specified in MIL-F-15618.
184.108.40.206 Minimum performance.
Minimum performance of pre-filter and
coalescer element shall be as specified in table I. The pre-filter and
coalescer shall not show signs of collapse or breakthrough during the test.
4.7.4 Filtration ratio test. When tested in the order specified in
table II, the pre-filter elements shall exhibit time average filtration ratios
at 3 micrometers equal to or greater than 100 and 5 micrometers equal to or
greater than 500.