MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

This type analysis can be developed for any water lifter to observethe annual and operating costs. Figure 6.2 presents the results of sucheconomic analyses for several water lifters used in developing countriesin such a manner as to compare them for selection purposes. Note that thisfigure is for a constant head and varying discharge, however other variablecombinationscan be utilized.Because not all water liiting operations can easily be evaluated inmonetary units, the following example is used to illustrate cost in termsof food consumed. It also analyzes the power and efficiency of the manualoperation for a bucket-piston pump.Example 6.2 (from Allison, 1975):1. Basic parameters:a) One small man under tropical conditions can provideabout 2200 ft-lb/min (0.067 hp).b) Human efficiency in converting food to mechanicalwork (beyond basal metabolism) is about 20%.c) Work capacity of one man at 2200 ft-lb/min is about5 hrs/day (excluding rest periods).d) A boro crop requires about 33.3 inches of water fora season of 120 days.e) Pump efficiency is about 50%.f) Crop yields 2,600 lbs of rice per acre.g) Area irrigated by single family unit is about 0.5 ac.2. Calculations:a) Energy input = 2200 ft-lb/min = 36.6 ft-lb/set.b) Energy delivered to water (50% eff) = 18.3 ft-lb/set.c) Energy required to lift 1 ft3 of water 10 ft =62.4 lb/ft3 x 10 ft = 624 ft-lb/ft3.