MIL-PRF-23798D(SH)
RUBBER MANUFACTURERS ASSOCIATION (RMA)/MECHANICAL POWER TRANSMISSION
ASSOCIATION (MPTA)/RUBBER ASSOCIATION OF CANADA (RAC)
IP-20
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Specifications for Drives Using Classical V-Belts and Sheaves (Joint
RMA/MPTA/RAC)
IP-25
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Specifications for Drives Using Variable Speed V-Belts (Joint RMA/MPTA/RAC)
(Copies of these documents are available from the Rubber Manufacturers Association, 1400 K Street, NW,
Suite 900, Washington, DC 20005 or online at www.rma.org.)
2.4 Order of precedence. In the event of a conflict between the text of this document and the references cited
herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws
and regulations unless a specific exemption has been obtained.
3. REQUIREMENTS
3.1 First article. When specified (see 6.2), a sample shall be subjected to first article inspection in accordance
with 4.2.
3.2 Materials. Cast iron shall not be used in fan-coil assembly nor shall cast iron be used in motors, which are
components of the fan-coil assembly. Gray cast iron may be used for the fan and motor sheaves. Materials for fan-
coil assemblies shall be corrosion-resistant or material shall be protected against corrosion after fabrication.
Material degraded during the fabrication process shall be normalized to restore those properties before assembled in
any fan-coil assembly. Selected materials shall be capable of meeting all of the operational and environmental
requirements specified herein.
3.2.1 Corrosion protection. Corrosion-resisting steel, galvanized steel, copper, and brass referenced herein are
considered corrosion-resisting materials. Corrosion resisting steel, when fabricated by any method that tends to
reduce corrosion-resisting properties, shall be normalized to restore those properties before being assembled in any
unit.
3.2.1.1 Corrosion protection methods. Parts fabricated from other than corrosion-resisting materials shall be
protected against corrosion after fabrication with chemicals, electrolytic processes, plating or paints. The following
methods while not restrictive are considered corrosion protection methods when properly applied.
a.
Hot-dipped galvanized in accordance with ASTM A123 with the spelter conforming to grade 5 of
ASTM B6.
b.
Electroplating with zinc in accordance with type LS of ASTM B633 followed by a phosphate treatment
conforming to method A of ASTM D2092.
c.
Hot phosphoric or chromic acid treatment, or a coating of primer in accordance with DOD-P-15328
followed by two coats of primer conforming to TT-P-645.
3.2.2 Hazardous material. Materials for use in the construction of fan-coil assemblies shall have no effect on
the health of personnel when the materials are used for intended purpose. Regardless of other requirements,
materials and parts containing asbestos, cadmium, lithium, mercury, or radioactive material shall not be used.
3.2.3 Fasteners. Material for all bolts, nuts, studs, screws and similar fasteners shall be corrosion-resistant
passivated, or of a material rendered resistant to corrosion. Sheet metal screws shall not be used. Galling shall be
prevented. Tapped holes shall be reinforced where shearing of thread can occur.
3.2.4 Dissimilar metals. Fan-coil assembly and components shall not degrade due to electrolysis in accordance
with MIL-STD-889.
3.2.5 Nonmagnetic material. When nonmagnetic fan-coil assemblies are specified (see 6.2), parts shall be
fabricated of nonmagnetic material, which has a maximum relative permeability of less than 2.0 after fabrication.
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