MIL-PRF-18953C(SH)
6.1.1 Vaneaxial fans, Types A and X-A. Types A and X-A fans are high efficiency units intended for air
conditioning systems and non-collective protection ventilation systems. Type A is shockproof; Type X-A is
identical dimensionally but is equipped with a commercial marine (service C) motor and is not required to be shock
resistant.
6.1.2 Tubeaxial fans, Types L and X-L. Types L and X-L fans are moderate-efficiency units intended for short
recirculating systems or for ventilating use in exterior bulkheads where resistance does not exceed 0.75-inch water
gauge. Type L is shock resistant. Type X-L has identical mounting dimensions but is not required to be shock
resistant.
6.2 Acquisition requirements. Acquisition documents should specify the following:
a.
Title, number, and date of this specification.
b.
Type required (see 1.2.1).
c.
Requirement for nonmagnetic fan-motor (see 3.2.3).
d.
Fan characteristic code in accordance with 1.3 including fan type (see 1.2.1), size (see 1.2.2), motor
current (see 1.2.3), motor voltage (see 1.2.4), motor enclosure (see 1.2.5), ambient temperature (see
e.
Additional painting requirements (see 3.3).
f.
If high impact shock resistance is not required (see 3.13.2).
g.
Requirement for motor thermal protection (see 3.11.1.1).
h.
Waiver of requirement for sealed insulation motors when ship did not originally have a sealed
insulation motor and has a short remaining service life (see 3.11.1.1).
i.
Requirement for quiet motor (ABEC 5) bearings (see 3.11.1.4).
j.
Requirement for resilient mountings (see 4.8.1).
k.
Requirement for casing pressure test (Table III); specify test conditions if other than standard.
l.
Requirement for explosion proof motor (see 4.8.7).
m. Packaging requirements (see 5.1).
6.3 Qualification. With respect to products requiring qualification, awards will be made only for products
which are, at the time of award of contract, qualified for inclusion in Qualified Products List QPL No. 18953
whether or not such products have actually been so listed by that date. The attention of the contractors is called to
these requirements, and manufacturers are urged to arrange to have the products that they propose to offer to the
Federal Government tested for qualification in order that they may be eligible to be awarded contracts or orders for
the products covered by this specification. Information pertaining to the qualification of products may be obtained
by writing Commander, Naval Sea Systems Command, ATTN: SEA O5Q, 1333 Isaac Hull Avenue, SE, Stop 5160,
Washington Navy Yard DC 20376-5160 or email to commandstandards@navsea.navy.mil, with the subject line
"QPL Comment". Since contact information can change, you may want to verify the currency of this address
information using the ASSIST Online database at https://assist.daps.dla.mil.
6.4 Subject term (key word) listing.
Blade
Hub
Impeller
Nose piece
Vane
6.5 Changes from previous issue. Marginal notations are not used in this revision to identify changes with
respect to the previous issue due to the extent of the changes.
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