On account of the importance of preventing losses
of the charge in the pipes the author recommends the utilization of sluice-valves of the type shown in Fig. 60, instead of the usual cone or plug type.
Fig. 60.—Vanne sluice-cock.
Water-Tanks.—The reservoir is mounted in such a way that its base is flush with the top of the cylinder; it should be as near as possible to the cylinder in order to obviate the use of long inlet and return pipes. This fact, however, does not necessarily render it advisable to place the reservoir in the engine-room; for such a disposition is doubly disadvantageous in so far as it does not permit a sufficiently rapid cooling of the circulating water by reason of the high temperature of the
surrounding air, and in so far as it is liable to cause the formation of vapors which injuriously affect the engine. Consequently, the reservoir should be placed in as cool a place as possible, preferably even in the open air; for the water is not likely to freeze, except when it has been allowed to stand for a considerable time. The reservoir should be left uncovered so as to facilitate cooling by the liberation of the vapors formed on the surface of the water.
Circulation being effected solely by the difference in specific gravity or density between the warmer water emerging from the cylinder and the cooler water which flows in from the reservoir, the slightest obstruction will impede the flow. Hence, the cross-section of the pipes should not be less than that of the inlet and outlet openings of the cylinder of the engine. Good circulation cannot be attained if the water must overcome inclines or obstacles in the pipes themselves. Instead of elbows, long curves of great radius, limited to the smallest possible number, should be employed. This is particularly true of the return-pipe extending from the cylinder back to the reservoir. For this pipe a minimum incline of 10 to 15 per cent. should be allowed, in order that the water may run up into the reservoir. The height of the water in the reservoir should be from 2 to 4 inches above the discharge of the return-pipe. In order to maintain this level it is advisable to use some automatic device such as a float-valve, in which case the reservoir should not be allowed to become too full.
Fig. 61.—Correct arrangement of tanks and piping.