NATIONAL ALUMINIUM COMPANY LIMITED - Rites

The media of the filter shall be made from either special synthetic non non-woven bond fiber
design or made from micro fiber glass media. It shall be supported with GI wire mesh or
aluminum mesh and shall be housed in an aluminum sheet frame. It shall be of washable
type several times.
17.6.21 Package A/C Unit
17.6.22 .22 A separate cubicle shall be provided within the overall casing to house the thermostatic
controls, which shall be electric/electronic solid state, prewired and tested. The refrigerant
system shall be protected by pressure limiting devices, electric and thermal overloads and
unloading facilities to provide the required control range tolerances. A low voltage room
thermostat shall be provided for wall mounting. The casing shall be fitted with all necessary
coil drains and service connections/
entries.
17. . 6.23 PAC (duty/standby) units shall be selected manually and be ON/OFF switched. The units
shall be fully packaged and incorporate integral room air sensing control thermostats and
manufacturers work fitted safety interlocks. All controls shall be prewir prewired to unit mounted
control/power terminal boxes.
17.6.24 Ventilation and Air Conditioning system ducting
17.6.25 All GI sheet metal ductwork required for ventilation and air conditioning system shall be
furnished by the supplier. All ducts and plenums unless otherwise noted shall be constructed
out of standard quality galvanised steel sheet. All sheet metal ducts shall be fabricated and
installed in conformity to the requirements of IS:655. Steel supports for the ductwork shall
be furnished as required. The thickness of ducting steel shall be 1 mm min. For ducting with
large size exceeding 1300 mm it shall be 1.25 mm. The flexible connection between fan and
ducting shall be on Teflon impregnated canvas. The zinc coating on GI sheet shall be 275
gm/cm2.
17.7 DATA SHEET : VENTILATION SYSTEM
1.0 GENERAL
1.1.0 Mech. Ventilation System: To provide ventilation using fans for specified areas.
1.1.1 No. of air changes per hour
(a) For overground building: Not less than 10 supply air changes & 7 Exhaust air
changes
(b) For underground areas: Not less than 15 supply air changes & 7 Exhaust air changes
1.1.2 Equipment
(1) Underground tunnel: Centrifugal fans/Axial Fans
(2) All other places: Axial fans, roof ventilators
1.2.0 Pressurised ventilati ventilation on system: To provide clean air to all MCC / Switchgear buildings
1.2.1 No. of air changes per hour: Not less than 20
Technical Specification:Sec-4,System System Parameters, Operation & Control Philosophy
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