PACKAGE : I Bid Document VOLUME : II - Public Health Engineering

Gusseted bends and tees may be used for the filter pipe work. The completed head
clearance on access ways, sufficient ventilation to avoid excessive condensation and
adequate lighting. GEC exhaust fans shall be installed in filter house and main
machinery hall in sufficient nos. as required.
21.23 Wash water main.
Wash water supply pipe work shall be from the wash water tank provided for this
purpose. In case bidder, want to change this they may give justification adopting the
modified value in the bid.
21.24 Waste water collection and disposal.
To simplify the control of the cleansing process, the filter wash water shall
discharge from filter through piped outlets into open wasted channel running along
the length of the filter battery on the side of filtered water collection channel. The
channel shall be benched to fall. Channel velocities shall be self-cleansing and no
scouring.
21.25 Air scouring equipment.
In the machinery hall, the contractor shall supply two identical electrically driven
rotary air compressors for filter scouring purposes and preferably located above the
level of the filtered water collection channel. Each blower unit shall be of adequate
rating to supply air in the required quantity to efficiently scour one filter bed at a
time. The second blower unit shall act as standby. GEC exhaust fan shall also be
provided for proper ventilation. The blowers shall be air cooled and of the double
impeller positive displacement rotary type driven by electric motors and mounted
on a combination bed plate of cast iron or fabricated steel. Anti-vibration mountings
and flexible pipe joints shall be provided.
Each blower shall be complete with automatic unloading device, dead weight
pressure relief valves pressure gauges, inlet air filters and suitable in all respects for
automatic operation.
The driver between the blowers and motors shall be through flexible pin and buffer
coupling or of the vee rope type of approved design. The Impellers shall be of cast
steel, machined to an accurate contour, together with an integral shaft, and shall be
statically and dynamically balanced. The Blower shall run at maximum speed of
1000 rpm.
DTS : Detailed Tender Specification. Page 254