Product Sheet

Given the fact that there are millions of diesel pumps operating in South Asia, it is surprising that so little study has been made on their fuel efficiency so far.

There are two types of pumps in India:
(i) surface operated pumps where the pump and engine are both at ground level,  drawing up the water from a maximum of  8m and
(ii) deep-set pumps where the engine is at  ground-level but the pump is installed in a pit so as to be close to the water level.
The surface pumps are usually 5hp/1500rpm (Petter)  
models with a direct coupled centrifugal pump.  

For deep-set pumps, the slow speed Lister type engine is mostly used.

Improving existing pumps
In the Terai Plains, a study was launched by Practica on Petter surface diesel pumps l. It was found that the fuel efficiency was quite low. At a total head of 6m and a corresponding  discharge of 10l/s, the pumps consumed 1l/hour on the average.
A number of modifications were then tested and their impact measured. The modifications that were most effective proved to be:

• removal of the foot-valve/check-valve on

• the suction side

• reduction of the engine speed
• increase in cooling water temperature 

After modification, the fuel consumption dropped to only 0.5l/hour, at he same discharge of 10l/s.

Cost
The modifications are cheap and simple.
The average cost is US$10, which will be well within the means of the average farmer. At a diesel price of US$ 0.5/litre and a 50% saving, the pay-back period for modifying a pump-set will thus be 20 hours. Assuming an average annual running time of 500 hours, the farmer will after modification save US$ 100 per year.

Improved new pumps

The above modifications apply to existing usually oversized pumps that for years have been sold in the Terai Plains. At the same time efforts have been made has been made to improve on new pumps so that modification becomes superfluous. The following improvement have been introduced:
-Reduction of power from 3.5 to 2.5hp by reducing the speed from 1500 to 1000rpm
-Design of a new pump impellor and volute casing to suit the duty point at 1000rpm
-Providing the pump with a horizontal discharge spout to obviate the need for a bend
-Provide a 1.5- inch threaded connection on the pump housing for fixing the priming  pump
 
The above improvements on a newly manufactured pump set result in even higher fuel efficiency than modifications, with the additional advantage that the new set weights less than half of the original. This is relevant because increasingly pump sets need to be moved 
around.

Possible impact at national level
It is possible to make a rough estimate of the possible impact at national level as follows:

Assumed total number of diesel pump-sets in India 6 million

Assumed average annual operating time 500 hours

Assumed average fuel consumption 1.1 l/hour

Total fuel consumption of irrigation pumps 3.3 billion litre/year

Potential saving through modification 50% 1.6 billion litre/year

Status
The modification of existing pumps continues in North Bengal, at a moderate pace of several hundred pumps per year. The sale of the new fuel efficient pumps is currently estimated at about 5000 per year. 

Source: http://www.practicafoundation.nl/technologies/fuelefficient.html