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

The vertical column pipe assembly shall be of MS fabricated, double flanged type,
anti corrosive epoxy painted both inside and outside. The column piping shall be of
individual length nor exceeding 3.00 M each for effective and easy handling. I.D. of
the column pipe shall be such that maximum velocity at the highest flow condition
does not exceed 2.0 m/s.
The total suspension length including the bottom basket strainer shall be fixed by
the Bidder considering the minimum submergence requirement at the lowest water
level and max drawdown in the well and required bottom clearance from the bed of
the well etc. The contractor shall also consider the average drawdown in the well to
the tune of 0.8 m at the L.W.L. condition for arriving at the minimum submergence
level required. The total suspension length as may be considered in the offer backed
by technical justification shall be submitted with the technical offer. CFD analysis
report and recommendation of the corrective measure to be adopted for the sump, if
any shall be submitted by the contractor prior to supplying the pumps.
The pump shall be self, service water lubricated type. Self lubricated type guide
bearings are to be provided at suitable positions of the shafts and its spacing shall
not be more than 3.00 M (approximate) apart. Since the service water will carry
silica, sand, mud etc. the guide bearings shall have suitable passages with in them to
pass and the same may not stuck inside the bearings deteriorating them.
Separate thrust bearings at the pumps and motors shall be provided to take the
vertical thrust and wt. of the rotating assy. Thrust bearing shall be antifriction roller
with a Pt.100 probe so as to measure the pump bearing temp by RTD method.
Thrust bearing of pumps shall be oil lubricated and self water cooled. Motor thrust
bearing shall how ever be of grease lubricated and air cooled. Thrust bearing should
be designed in such a manner to be worked safely on any working condition even at
the respective shut off. The pump shall also withstand the condition of any back
flow and sudden pressure surges developed on it due to any reason what so ever.
The pump assembly should be provided with non-reverse ratchet assembly, bowl
bearing/suction bell bearing to be provided in each bowl both at above and below
the impeller shaft assembly, shaft sleeves including sleeve at gland packing point,
seal ring/wearing ring, double throat air valve at column vent point and other
important features as provided by the manufacturer. All fasteners used in the pump
assembly shall be of approved grade stainless steel.
The pump H.Q. characteristic curves shall be stable all through out. The pump
efficiency should be reasonably high and not less than 82% for the duty point at the
declared head flow conditions of each pump set to deliver the station flow including
additional 25% capacity at designed head condition. The head, discharge,
efficiency, KW absorbed, NPSHR should be guaranteed during, the duty point flow
condition without any tolerance. For other working points, as declared by the
DTS : Detailed Tender Specification. Page 190