3.3.2 Imperfections. If the filter element is of the type wherein resinous
or other material is used for elimination of imperfections, materials used shall
be compatible with the hydraulic fluid, and not q ore than 2 percent of the
filtering area shall be covered by the applied material.
3.3.3 Seals. Seals shall be synthetic rubber in accordance with
MIL-R-83248 and MIL-R-83248/1.
3.3.4 Recovered materials. Unless otherwise specified herein, all equip-
ment, material, and articles incorporated in the products covered by this
specification shall be new and may be fabricated using materials produced from
recovered materials to the maximum extent practicable without jeopardizing the
intended use. The term "recovered materials" means materials which have been
collected or recovered from solid waste and reprocessed to become a source of raw
materials, as opposed to virgin raw materials. None of the above shall be
interpreted to mean that the use of used or rebuilt products is allowed under
this specification unless otherwise specifically specified.
3.4.1 Filter element. The filter element shall be cylindrical in shape and
shall consist of a filter medium that shall be supported to withstand the side
and end loads imposed during testing as specified in 4.7. The filter element
shall be of the disposable type, designed for flow from outside in
shall be equipped with seals as specified in MIL-R-83248.
3.4.2 Dimensions. The filter element dimensions shall be as specified in
the specification sheet.
3.4.3 Element covering. The element shall be constructed with an outer
wrap of metal screen or perforated metal to protect the filter media pack from
damage during handling.
3.5.1 Fabrication integrity. (bubble point). The filter element's bubble
point shall be equal to or greater than the value specified in the specification
sheet when tested as specified in 4.7.1.
3.5.2 Filtration performance. Unless otherwise specified in the specifi-
cation sheet, at least two filter elements shall be subjected to this test. The
filter element when tested as specified in 4.7.2, shall exhibit the following
(a) Filtration ratio (beta ratio,
a minimum beta ratio (see
6 4.1) equal to or greater than the value specified in the
applicable specification sheet.
(b) Dirt holding capacity: normalized capacity (see 6.4.2) equal to
or greater than the value specified in the applicable specifi-
cation sheet at a terminal pressure drop (see 6.4.4) of 40
(c) Clean element pressure drop: at rated flow of fluid in
accordance with MIL-H-17672 a clean element pressure drop equal
to or less than the value specified in the specification sheet