FIG. 70.—Expectancy Curves for Pumping Engines Working against a Pressure of 100 Pounds per Square Inch.
J. N. Chester, Journal Am. Water Works Ass’n, Vol. 3, 1916, p. 493. ]
=87. Costs of Pumping Machinery.=—The cost of pumping machinery can not be stated accurately as the many factors involved vary with the fluctuations in the prices of raw materials, transportation, labor, etc. The actual purchase price of machinery can be found accurately only from the seller. The costs given in this chapter are useful principally for comparative purposes and for exercise in the making of estimates. The costs of complete pumping stations are shown in Table 31.[48] These figures represent costs in 1911.
These costs include the best type of triple-expansion engines, high-pressure boilers, brick or inexpensive stone building with slate roof, chimney and intake. Cost of land is not included. ─────────────────┬─────────────────┬─────────────────┬───────────────── Discharge │ Horse-power per │ │ Pressure, Lbs. │ Million Gals. │Cost, Dollars per│Cost, Dollars per per Sq. In. │ Pumped │ Horse-power │ Million Gallons ─────────────────┼─────────────────┼─────────────────┼───────────────── 30│ 12│ 562│ 6,750 40│ 16│ 438│ 7,000 50│ 20│ 362│ 7,250 60│ 24│ 312│ 7,500 70│ 28│ 277│ 7,750 80│ 32│ 250│ 8,000 90│ 36│ 229│ 8,250 100│ 40│ 213│ 8,500 110│ 44│ 200│ 8,750 120│ 48│ 187│ 9,000 130│ 52│ 192│ 10,000 │ │ │ ─────────────────┴─────────────────┴─────────────────┴─────────────────
=88. Cost Comparisons of Different Designs.=—In the design of a pumping station and its equipment the relative costs of different designs should be compared, and the least expensive design selected, due consideration being given to serviceability, reliability, and other factors without definite financial value. In comparing the costs of different types of machinery, all items in connection with the pumping station should be considered. For example, the cost of an electrically driven centrifugal pump and equipment may be less than the total cost of a steam driven reciprocating pump and equipment because of the saving in the cost of boilers, boiler house, etc., but a comparison of the capitalized cost of the two might show in favor of the reciprocating steam pump because of the lower cost of operation.