Evaluation of the characteristics of petti and para (axial flow pump)
Loading...
Files
Date
1988
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Irrigation and Drainage Engineering, Kelappaji College of Agricultural Engineering and Technology, Tavanur
Abstract
‘Petti and Para’ is the most popular pumping equipment used in Kuttanad and Kole lands of Kerala for dewatering agricultural fields. It is a local adaptation of the class of pumps called axial flow or propeller pumps. It is fabricated by local blacksmith using their practical experience and is very popular in low head high discharge requirements especially for drainage purposes.
The project was undertaken to evaluate scientifically the ‘Petti and Para’ and to suggest improvement to its design.
Field survey had been conducted to study the general characteristics of the existing ‘Petti and Para’ and the energy requirements for punja and additional crop. Field pumping tests were conducted on 15 hp and 20 hp ‘Petti and Para’ using standard methods, to evaluate its characteristics.
A small propeller pump was developed talking into consideration the specific requirements of Kuttanad, so that the results could be utilised in bigger units through the principles of similitude. The pump was designed as a high specific speed unit (280 rpm) operating at high rotational speed (1900 rpm), so that its physical dimensions were small.
The field survey showed that ‘Petti and Para’ are operating at low speed of 300 rpm. The most common type of ‘Petti and Para’ in use are 10 hp, 15 hp, 20 hp, 30 hp and 50 hp units. A 10 hp unit has an impeller diameter of 44 cm and 50 hp unit has an impeller diameter of 79 cm.
The average energy consumption for dewatering during punja crop was 309.8 kwh per hectare and that for additional crop was 444.5 kwh/ha.
The efficiency of a 15 hp ‘Petti and Para’ having an impeller diameter 52 cm was about 20%. It could pump water at a rate of 217.75 to 143.60 1/s against a total head of 65 cm to 100 cm.
A perfectly maintained 20 hp ‘Petti and Para’ could pump water at a rate of 369.5 to 281.2 1/s under total head of 73.2 to 132.01 cm. The efficiency of the unit varied between 21.47 to 25.96 %.
The newly developed propeller pump having an impeller diameter of 145 mm was tested at constant static head of 120 cm. It could pump water at a rate 39.64 to 13.34 1/s against a total head of 183.1 to 283.02 cm. The efficiency of the unit varied between 23.72 to 9.6 Input power varied between 4.076 to 5.21 hp, while utilising a 10 hp induction motor as power unit. Due to lack of time this work is inconclusive. Further elaborate studies are necessary for making specific recommendation for the improvement in the efficiency of ‘Petti and Para’.
Description
Keywords
null