Coolers.—The arrangement which is illustrated in Fig. 65, and which has the merit of simplicity, will be found of service in cooling the water. It comprises a tank B surmounted by a set of trays E, formed of frames to which iron rods are secured, spaced 1 to 2 feet apart, so as to form superimposed series separated by 11⁄2 to
21⁄3 feet. On these trays bundles of tree branches are placed. The cold water at the bottom of the tank is forced by the pump Pi into the water-jacket, from which it emerges hot, and flows through the pipe T, which ends in a sprinkler G, formed of communicating tubes and perforated with a sufficient number of holes to enable the water to fall upon the trays in many drops. Thus finely divided, the water falls from one tray to another, retarded as it descends by the bundles
of tree branches. It finally reaches the tank in a very cold condition and is then ready to be pumped to the engine. Birch branches are to be preferred on account of their tenuity.
Great care should be taken to cover the tank with a sheet-metal closure in order to prevent twigs and foreign bodies from entering and from being drawn into the pump.
Fig. 66.—Fan-cooler.
In the following table the dimensions of an operative apparatus of this kind are given,—an apparatus, moreover, that may be constructed of wood or of iron:—
| Horse-power. | Volume in cubic ft. | Tank Base. | Tank Height. | Height of tray-base. | Pump—Capacity in gals. per min. |
|---|---|---|---|---|---|
| 30 | 105 | 4.9' x 4.9' | 4.4' | 6.6' | 16.71 |
| 40 | 154 | 5.2' x 5.2' | 5.6' | 7.4' | 18.69 |
| 50 | 190 | 5.7' x 5.7' | 6.4' | 8.1' | 21.99 |
| 75 | 350 | 6.6' x 6.6' | 8.1' | 9.1' | 35.18 |
| 100 | 490 | 7.4' x 7.4' | 9.1' | 9.1' | 43.98 |
In order that the water may not drop to one side, the base of the apparatus should be made 10 to 12 inches less in width than the tank.
The size of these apparatus may be considerably reduced by constructing them in the form of closed chests, into the bottom of which air maybe injected by means of fans in order to accelerate cooling (Fig. 66).