MIL-PRF-18953C(SH)
3. REQUIREMENTS
3.1 Qualification. The fans furnished under this specification shall be products that are authorized by the
qualifying activity for listing on the applicable qualified products list before contract award (see 4.2 and 6.3).
3.2 Materials. Fan shall be of spark-resistant construction as defined in AMCA 99-0401 Type B construction.
Cast iron, excluding nodular iron, shall not be used in the construction of the fans nor shall cast iron be used in fan
motors which are components of Types A and L fans. Materials shall be corrosion resisting 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. Selected materials shall be capable of meeting all of the
operational and environmental requirements specified herein. Non-metallic materials for the fan casing and impeller
shall be avoided due to fire and smoke concerns.
3.2.1 Hazardous material. Materials for use in the construction of fans 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.
3.2.2 Fasteners. Material for all bolts, nuts, studs, screws and similar fasteners shall be corrosion-resistant
passivated or of a material rendered resistant to corrosion. Self-tapping sheet metal screws shall not be used.
Galling shall be prevented. Tapped holes shall be reinforced where shearing of thread can occur.
3.2.3 Nonmagnetic construction. When nonmagnetic fan-motor units are specified (see 6.2), all fan parts
including the casing, vanes, impeller, impeller bushing, motor mounting, fasteners, washers, conduit box, and
fittings shall be of nonmagnetic material. Nonmagnetic material is defined as a material that has a maximum
relative permeability of less than 2.0 after fabrication.
3.2.4 Motor material. Motor material shall conform to the requirements of IEEE STD 45 or NEMA MG 1 for
nonmagnetic motors.
3.2.5 Dissimilar metals. Fans and components shall not be degraded due to electrolysis.
3.2.6 Faying surfaces. Faying surfaces shall be protected against corrosion.
3.2.6 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally
preferable materials should be used to the maximum extent possible, provided that the material meets or exceeds the
operational and maintenance requirements, and promotes economically advantageous life cycle costs.
3.3 Painting. Equipment and component items shall be painted as specified (see 6.2). If paint requirements are
not specified, use standard factory finish.
3.4 Welding and allied processes. Surfaces of parts to be welded or brazed shall be free from rust, scale, paint,
grease, and other foreign matter. Welding and allied processes shall be performed by personnel certified to AWS
B2.1 and B2.2. NAVSEA Technical Publication S9074-AR-GIB-010/278 shall be used for guidance.
3.5 Identification plates. Each fan shall be provided with a permanently attached corrosion-resistant
identification plate. Attachment methods for the identification plate shall be corrosion-resistant. The identification
plate shall contain the following information as a minimum:
a.
National stock number
b.
Manufacturer's name, commercial and government entity (CAGE) number, and part number
c.
PIN code
d.
Direction of airflow and rotation
e.
Bearing lubrication
The identification plate and a duplicate motor identification plate shall be installed on the outside of the fan
casing.
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