DESIGN, DEVELOPMENT AND PERFORMANCE EVALUATION OF POLYMER CASTED CENTRIFUGAL PUMP
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Date
2017
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Publisher
Acharya N.G. Ranga Agricultural University
Abstract
In India, agriculture plays a major role in economy and livelihood. Majority of the
population of India depends on agriculture hence more water resources (about 80% of total
water) and energy resources are required for the irrigation in dry seasons. Since resources
are limited and have to be conserved for future use, any effort for their proper utilization
and conservation cannot be neglected. The present research problem, “Design,
Development and Performance Evaluation of Polymer Casted Centrifugal Pump” was
taken up for the benefit of farming community and other sections like domestic and
industries in the way of financial feasibility and technical possibility. In our country many
of the centrifugal pumps are made up with cast iron. In the present study a cast iron pulley
operated centrifugal pump was selected which has 11 components namely casing,
impeller, shaft, pulley, bearing stand, bearing cover, top flange, bottom flange, gland,
counter weight and base. It was found that the present existing centrifugal pumps have
many technical disadvantage related to its cost, weight, corrosion and wear and tear.
During the study it was found that these technical disadvantages can be overcome
by replacing the metallic parts of pumps with the engineering plastic materials. There are
polymeric materials like Poly Phenylene Oxide (PPO) or Noryl, Delrin, Vespel, Zytel, Cast
Nylon, Ultra High Molecular Weight Polyethylene (UHMWPE) and Poly Ether Ether
Ketone (PEEK) are commercially available in the market.
The following polymers are recommended as alternative materials for making the
centrifugal pump.
S.No. Name of the pump
Component
Existing metallic
material Alternative Polymer
1 Casing Cast Iron UHMWPE
2 Impeller Cast Iron Cast nylon
3 Shaft Cast Iron Delrin
4 Bearing stand Cast Iron Cast nylon
5 Bearing cover Cast Iron Delrin
6 Top flange Cast Iron UHMWPE
7 Bottom flange Cast Iron UHMWPE
8 Gland Cast Iron Cast nylon
9 Counter weight Cast Iron Delrin
10 Pulley Cast Iron Delrin
11 Base Cast Iron Cast nylon
The 3-D models of all 11 pump components were developed and designed by
Co-ordinates Measuring Machine (CMM) and the models were loaded in Computational
Fluid Dynamics (CFD) ANSYS 16.0 software for simulating the results. All the 11 pump
components were taken 16 hours time in CMM for development and design of 3-D models.
Based on the optimization and selection of polymers to replace the metal pump
components the fabrication of polymer pump components were done by Computer
Numerical Control (CNC) lathes and milling machines. Among the 7 polymer materials
identified 3 were selected and used for machining of 10 pump components except shaft of
the pump. The shaft was initially made with Delrin polymer material later on for avoiding
the frequent breakage of shaft by packing rope and oil seal, it was finalized to machine
with stainless steel only. The study concluded with rest of the 10 individual pump
components were machined based on their properties, characteristics and technicalities
with 3 polymer materials viz. Cast Nylon, UHMWPE and Delrin. After machining, all the
pump components were assembled with the nut, bolts, washer and packing ropes as same
as metal pump. The polymer pump was connected to 0.5 hp low speed single phase motor
and v-belt and was set for experiments in field irrigation laboratory at College of
Agricultural Engineering, Bapatla. After completion of all experiments of head, discharge,
pressure and power consumption with polymer pump, the metal pump was also operated
with the same motor and conditions for comparison.
The discharge of both metal and polymer pumps at 1m, 2 m, 3 m, 4 m, 4.5 m and 5
m suction heads were same as 1.2 l/s, 1.1 l/s, 1.0 l/s, 0.9 l/s, 0.9 l/s and 0.8 l/s respectively.
The pressure of both metal and polymer Pumps at 1 m, 2 m, 3 m, 4 m, 4.5 m and 5 m
suction heads were same as 0.5 kg/cm2
, 0.5 kg/cm2
, 0.4 kg/cm2
, 0.3 kg/cm2 and 0.3 kg/cm2
respectively. The time taken for one unit (1 kW) power consumption of both metal and
polymer pumps at different heads taken same as 1.5 h in all cases. The rpm of motor and
polymer pump at 1m, 2 m, 3 m, 4 m, 4.5 m and 5 m suction heads were 1392 and 2491,
1382 and 2486, 1378 and 2485, 1368 and 2471, 1366 and 2466 and 1362 and 2465
respectively. The rpm of motor and metal pump at 1 m, 2 m, 3 m, 4 m, 4.5 m and 5 m
suction heads were 1408 and 2647, 1406 and 2639, 1398 and 2635, 1396 and 2632, 1394
and 2631 and 1387 and 2624 respectively. The polymer pump was operated for 310 h till
date and found no wear and tear. It was noticed that the total weight of the metal pump was
5.7 kg and polymer pump was only 1.7 kg. By replacing the metal components of
centrifugal pump with the polymers the weight of the pump was reduced by 70 per cent
and become very light in weight.
Based on CIPET estimation on mold cost and component cost, the production cost
of one lakh polymer pumps were projected and the difference of both metal and polymer
pumps was calculated. The mold cost of one polymer pump was 24.5 lakh and production
cost one polymer pump was Rs.485 when compared to metal pump market price of Rs.
1200. The projected cost of 1 lakh polymer pumps was Rs. 4.85 cr. and 1 lakh metal pumps
market price was Rs. 12 cr. and the difference of cost was Rs. 7.15 cr. The projected cost of
5 lakh polymer pumps was Rs. 24.25 cr. and 5 lakh metal pumps market price was Rs. 60
cr. and the difference of cost was Rs. 35.75 cr. By replacing the metal pump with the
polymer pump the cost of the pump was reduced by 59.6 per cent, making it very cheap.
Description
D5469
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