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

The pump TBH shall be calculated by the Bidder considering the station losses and
the minimum water level condition at (duty point).
Pump operating points at all the above stated service combination of pumps shall
also be evaluated and furnished for L.W.L. and maximum H.W.L. conditions within
the range.
The drive motor of the pumps shall be coupled with 4 poles. The pump parameter
shall be designed at a speed of 1400 Rpm.
Bowl assembly shall be either single or multistage, centrifugal or mixed flow design
with discharge coaxial with the shaft and the type of impeller shall be chosen on the
basis of the pump specific speed and the characteristics of the liquid handled.
Pumps shall have provision for adjustment of impellers in vertical direction from
the top of the thrust bearing. The adjustment mechanism must take into
consideration the extension of the line shaft due to hydraulic down thrust, weight of
the shaft and impeller.
The pump shall be capable of continuous operation. Impeller shaft, line shaft and
head shafts shall be accurately sized and selected on the basis of maximum torque
to be applied on the pump shaft. Replaceable sleeves are to be provided at desired
points.
Critical speed shall be well away from the operation speed and in no case shall lie
between 90% and 110% of the rated speed.
The stuffing box shall be self sealed design provided with packing and preferably
with split type gland.
The pumps shall be protected against dry running or operation below the minimum
submergence level through suitable sensing devices like Float/Level sensing switch/
probe by tripping the motor to avoid such condition. There shall also be one level
indicator, common to all pumps in the well to be provided by the contractor.
Total sensing device & all relevant indicating & control apparatus along with wiring
cabling etc. shall be inclusive in the scope of work of the contractor.
The suspension length of the pump assembly shall be such that it can safely work at
the L.W.L. condition of the reservoir/intake well. One suitable basket type strainer
of S.S. (for preventing entry of foreign particle and solid) in the pump shall be
provided to each pump. All fixtures, clumps etc. as necessary for the multiple pieces
column pipe and shaft assembly of the pumps shall be provided by the contractor
under the scope of this specification.
DTS : Detailed Tender Specification. Page 189