NATIONAL ALUMINIUM COMPANY LIMITED - Rites

15.2.8 Hoods over the conveyor head pulleys shall be made of suitably stiffened minimum 4 mm
M.S. Plates and shall be provided with hinged and gasketed inspection doors with suit suitable
access to them. Further, serrated rubber seal shall also be provided at the very inlet of head
chute to minimise dust nuisance.
15.2.9 Separate maintenance sealed door shall be provided for access to belt cleaners in head
pulley hood impact plates, flap gates for maintenance and inspection doors shall be of
hinged with positive locking facility.
15.3. Skirt Boards
15.3.1 Skirt board shall ensure centralised loading of conveyor belt to avoid coal spillage. Suitable
‘Skirt Plates’ of minimum 3.0 meters length shall be provided at each feeding point of
conveyor. The width of the Skirt Boards shall be two two-third third the conveyor belt width width. In the
beltswhere coal of appreciable lump size (250 mm) is being conveyed conveyed, , the gap between the
bottom of the skirt board and the belt shall be made to increase uniformly in the direction of
belt travel. The height of the skirt boards shall be sufficient to contain the material volume
as it is loaded on the belt and shall not be less than 750 mm. The skirt plates shall be fitted
with modular segmented and replaceable rubber skirting pads having facility of adjusting the
pressure on the belt conveyor and shall have provision of on line removal for the purpose of
easy maintenance. Such segmented rubber pads with its holdi holding ng down adjustment
arrangements shall be of proven design. The edges of segmented pads shall be installed at
an angle for providing a better seal. All care shall be taken while designing, to combine good
sealing with minimum belt wear.
15.4 Flap Gates
15.4.1 The motor operated 2 position flap gates shall be provided in transfer chutes as specified
and shall be complete with electrically operated actuators. The gates shall be of robust
construction and suitable for trouble free operation. The face of the flap gate shall be made
out of 20 mm thick TISCRAL or equivalent material.
15.4.2 The equipment shall be capable of being operated for at least 15 switchings per hour at
rated load and thrust and shall be suitable for 10 Nos. consecutive switchings at r rrated
load
and thrust. The equipment shall be shop tested to prove this requirement.
15.4.3 The motor rating for the actuator shall be so selected as to provide sufficient thrust for
operation of the flop gates against the moving weight of coal and/or fla flap p gate. The flap gate
travel shall be in the range of 60 deg. to 70 deg. The motor shall be completely dust tight.
15.4.4 Lever arm shall be provided between actuator and flap gate shaft for obtaining required
thrust. The linkage mechanism proposed shall be indicated in the Bid.
15.4.5 The actuators shall be capable of preventing any over travel. Suitable travel dependent limit
switches controlling the travel of the flop gates on either direction shall be furnished. These
Technical Specification:Sec-4,System System Parameters, Operation & Control Philosophy
Page 31 of 64