NATIONAL ALUMINIUM COMPANY LIMITED - Rites

17.6.10 Rain protection cowls will be de designed signed to suit wall exhausters/supply fans for protecting
fans/motors from rain. It will be provided with bird screen.
17.6.11 Inlet cone or bell and outlet cone shall be provided as required. It should be made of G.I. or
M.S.
17.6.12 Motor shall be of totally otally enclosed type complying with the companion electrical
specification. Suitable rain/sun shade for motors shall also be provided.
17.6.13 Centrifugal Fan
Centrifugal fans shall be provided as required.
17.6.14 The casing shall be of welded construction fabricated with heavy gauge material. It shall be
rigidly reinforced and supported by structural angles. The seams shall be permanently sealed
airtight. Split casing shall be provided on larger sizes of fans. Casing drain with valves shall be
provided wherever required.
17.6.15 The impeller shall have die formed curved blades fabricated out of MS heavy gauge welded
to the rim and back plate to have a non overloading characteristics of the fan. Rim shall be
spun to have ve a smooth contour. If required intermediate stiffening rings shall be required.
The impeller, pulley and shaft sleeves shall be secured to the shaft by key and/or nuts. The
impeller along with driven pulley shall be dynamically balanced. Fan shaft shall be of EN-8
equivalent.
17.6.16 The bearings shall be self self-aligning heavy-duty duty ball or roller bearings. They shall be
adequately supported. They shall be easily accessible and lubricated properly from outside.
17.6.17 Filters
17.6.18 Metallic Filters
Metallic allic cleanable filters shall consist of VV-fold
fold galvanised wire mesh inter spaced with a flat
layer of galvanised wire mesh. The density of the filter medium shall increase in the direction
of airflow. Wire mesh edges shall be suitably hemmed to eliminate the danger of abrasion
during handling. Filter medium shall be supported on either side by galvanised expanded
metal casing. Filter frame shall be constructed from galvanised sheet of thickness not less
than 18 gauge.
17.6.19 HDPE Filters
HDPE filters shall all be provided as required. This shall be constructed of HDPE fabric with
continuous water spraying on it from a header for keeping it clean.
17.6.20 High efficiency filter (for A/C purpose)
Technical Specification:Sec-4,System System Parameters, Operation & Control Philosophy
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