Pumps of several kinds are employed in soap-works, for removing spent lye and soap from the coppers. For small pans, a simple hand suction-pump answers; for larger ones, a single- or double-acting lift- or force-pump may be placed inside the copper, and worked by hand, or by an eccentric on a shaft. In large factories, some form of centrifugal pump is found useful. Their great advantages are the absence of valves and easily deranged working parts, and the large amount of work they can do In a short time. The pumps made by J. & H. Gwynne, 89 Cannon Street, London, are in most favour in England; the form usually employed in America is that bearing the name of Hersey Bros., Boston, Mass., which is represented in Figs. 63, 64, 65. The pumps require to be connected with pipes having swing joints to permit their being raised and Towered at will. To avoid the pipe system becoming choked by soap congealing in it, a stenm-pipe should be inserted at one end, to warm the pipes and pump previous to use, and to "blow out" all their contents at the end of the operation. ln the illustrations, S is the auction-pipe; H, delivery-pipe;f, blades set upon a cone (the rotation of which in the closed case produces the pumping), which is kept in its place by adjustable set screws.
This pump will transfer to any desired part of the factory, lye, melted fat, finished soap (if not too stiff), "nigre," and soft curd. The diameter of the pump is 10 in., of its outlet 2 1/2 in.; when making 120 rev. a minute, it will pump 6000 gal. an hoar, its. contents being twice emptied in each revolution.