Total cost Cost per kilowatt of firm station capacity Cost per pound Fuel economy Engine speed Piston speed Standardization Maintenance Delivery This analysis led to the elimination of General Motors because of light weight and high speed, and of Caterpillar because of high cost and maximum size limitation of 90 kw. The evaluation of Fairbanks-Morse and Worthington bids was accomplished on the basis of relative importance of the individual criteria listed above. These two proposals were based upon the standard units of each manufacturer. Fairbanks-Morse's bid was upon eight 142 kw and six 118 kw units, while the Worthington proposal was based upon six 237 kw units and six 125 kw units. Either of these proposals would fit the design requirements, and the contract was awarded to Fairbanks-Morse upon the basis of low bid. The Fairbanks-Morse diesel engine-generators selected were available in three sizes, 5, 6, and &cylinder engines, all identical except for the number of cylinders, and providing the maximum interchangeability of parts as well as flexibility in selection of units to fit the load requirements of each plant. The generating capacities of the three sizes were 118 kw, 142 kw and 195 kw respectively, at 80 per cent power factor. All generators were wound for 2400 volts, 60 cycle, 3 phase alternating current when operating at 720 rpm. The diesel engine accessories consisted primarily of a lubrication oil cooler, lubrication oil filter and strainer, hand pump, gauge board, jacket water heat exchanger, fuel oil hand pump, fuel oil drain tank and heat recovery exhaust silencer. In addition, a make-up water expansion tank was also provided for each engine, Each engine was provided with a 200~gallon fuel oil day tank located outside of the building and connected to each engine by copper tubing under the floor of the plant. The heat recovery exhaust silencer was used to provide steam for the water distillation units, (For description of the distillation units see Chapter 5.13 of this volume.) One starting air system was used to provide air for all engines in any one plant and consisted of one electrically driven and one gasoline engine driven air compressor, together with receivers, 5-203