Lifting the wind-wheel is a major exercise. A one tonne hand cranked winch is fitted way up the tower. A long length of wire rope drops to the ground and is fastened to the wind-wheel assembly. Two long ropes are tied to the wheel and held by two teams of people. As the wheel is cranked up, the ropes are pulled to keep the wheel away from the tower, lest its blades should be damaged. The progress is slow and somewhat tense. In the last stages, a team of two on the work platform expertly wrestles the wheel assembly down and bolts the two bearing housings to the turn-table.
Rest of the assembly is straight forward. The tail assembly is lifted and mounted on the turn-table. The connecting rod is attached to the crank and left alone till the pump is assembled.
As the pump is meant to be submersible, it is made of stainless steel. It is a piston pump with a check-valve above the piston to control discharge and a foot valve at the bottom to control suction. It comes in three sizes: 1.5″, 2″ and 2.5″ dia. It can be submerged upto 210′ in water and it can discharge to a elevated holding tank set upto 25′ or so above the ground [-depending on tower height and other details of configuration – see Aureka site for data]
Let us review the variables: windwheel size, tower height, pump size and placement depth. The first[diameter, 15′ or 19′] determines the amount of wind intercepted and therefore the power. The second, the tower height is decided by the location and obstacles to the wind. The final two, pump size and depth at which it is placed are worth some detailed explanation.
The bore at pointReturn site was 6″ dia and drilled 200′ deep. When plumbed, water table was found to be just 18′ below surface. While that looks so promising, it does not tell the whole story. What is crucial is how fast the springs recharging the bore, replace drawn water. A methodical way to determine the safe depth at which the pump can be placed so that it doesn’t run dry, is to run a compression test. I did not do that as no reliable service provider was available within reasonable distance. In a compression test, well mouth is closed and a compressed air jet is injected at various levels and made to pump out water. The purpose is to discover at what level water is sustainedly dischargeable at the top. The air also clears up sediments and spring holes. Whenever possible this test should be run. Without it, there is bound to be some trial and error.
We discussed the issue and decided to use a 2.5″ dia pump and set it at 60′ depth. These turned out to be a wrong choices. How we overcame that and an another early problem will be the subject of another upcoming article. But on the morning of May 24, 3 days after the parts arrived at the site, there was excitement in the air: the first run would be at around 10am. Babu Reddiar, got busy from early morning to organise a somewhat elaborate pooja to commemorate the event and to dedicate the windmill. A tiny crowd began to gather as the news began to spread. I was struck by how much seriousness, how much consensus existed among the humbler folk of rural India about the procedure for such a ceremony. Everyone listened raptly to Babu Reddiar giving authoritative instructions and watched Kutty, pointReturn’s handyman as he implemented them. I learnt much.