Oil vs. Steam in Small Plants
There seems very little doubt that for the small water works plant the oil engine is one of the ideal methods both from the standpoint of economy and efficiency, for driving the pumps. This is especially true at this time, when the cost of coal as a fuel makes steam as a motive power more expensive than ever before.
But there are certain things to be borne in mind in order that these small departments shall obtain the best results from the installation of such engines. One of these is that it is always wise not only to be certain that it is investing in a good engine, and not one at the lowest amount bid by the manufacturers, but also that the installation shall be amply able to take care of the maximum demands of the water works and, even better, have a capacity considerably in excess of present requirements. It is the very poorest economy to attempt to save money by under-equipping a plant.
Another very important provision and one that should be considered by even the smallest plants, is the plan of installing two power and pumping units, independent of each other, so that in case of breakdown or other disablement of one of them the other can be at once brought into service. The extra unit is also of great service in taking care of any additional load over the usual requirements of the system.
Such double equipments are especially valuable in cases of fire, when the full capacity of both engines can be drawn upon, it necessary. For this reason the two units should be independent also in their water supply and, if a well system, should be connected with independent wells. By this means the highest efficiency of the oil engine can be secured.