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

Bidder for solo and parallel operation in different level conditions (L.W.L, Normal
H.W.L. and Maximum H.W.L. and any other level within the range between
L.W.L. & Maximum H.W.L.) of the reservoir, the performance figures may follow
the tolerance limit as indicated in IS:1710.
The wetted portion of the pump assy should have a proper finish. Bowl efficiency
below 82% on duty point shall not be acceptable and the efficiency here means the
guaranteed bowl efficiency at the duty point. Pumps offered with higher efficiency
shall be appreciated. However no appreciation shall be given for the pumps with
bowl efficiency greater than 83%. After pumps performance test at manufacturer’s
works, the achieved bowl efficiency, if found to be less than that had been declared
as guaranteed, the pump shall not be accepted.
The pump rotating assembly should be accurately balanced statically and
dynamically as per IS:11723. No hole or any piece welded/bolted on pump impeller
for balancing shall be allowed. The shafts should be ground all over and perfectly
aligned. Special care should be taken that the entire pump assy do not experience
vibration beyond the permissible limit as per IS:11724, of such class rotodynamic
unit while operating even in worse operating condition at any combination. The
pump motor shall be considered as a single unit & the vibration limit should be
within the limit specified. The noise level shall be within the permissible limit of
IS:12065.
19.6 Drawing, data, curves and manuals.
The Bidder shall have to submit maximum Power absorbed by the pump on the
entire range where the range means the range between shut off and the declared run
out. This indicated power shall not be with any positive tolerance. At the maximum
flow of the declared range, the NPSHR shall be indicated without any positive
tolerance. The difference between the eye of the impeller and the entry point shall
be indicated. There shall be a minimum margin of 0.5m between the NPSHR and
NPSHA at the duty point flow condition, even working at the L.W.L. of the
reservoir and supporting calculation are to be furnished with the offer. Similarly the
pump shall have also adequate margin (at least 0.5m) on the NPSHR over NPSHA
at the highest operating level of the reservoir with highest flow of the entire range
of operation. The impellers for the pump shall not be at the lowest trim or the
highest trim of the same pump family. The pumps shall be so selected that the
declared run out flow is at least 125% of the guaranteed duty point flow. The other
working points within the range for solo and 2 pumps parallel operation at L.W.L.,
normal H.W.L. and maximum H.W.L. conditions shall be well within the declared
run out flow point.
DTS : Detailed Tender Specification. Page 191