The air is expelled from the cylinder by admitting steam without appreciable pressure, i.e., to balance that of the atmosphere, after which the steam exhausts into the surface condenser, in which a constant vacuum is maintained. Steam is then admitted automatically into the power cylinder, breaking the vacuum and imparting to the piston the required impetus. This principle is identical with that of the ordinary condensing steam engine, with the exception of the very low steam pressure in this connection.
Fig. 456.
This engine can be operated satisfactorily in combination with an ordinary house-heating boiler (low pressure), hence the expense of running it is very low during the steam-heating season. During the summer months the boiler connected with this engine can be used advantageously.
The bearings are self-oiling, and the cylinder condensation furnishes ample protection for the inside of the engine cylinder. There are no leather packings to burn out, and this is remarkably free from the objections to the older types of caloric engines.
These pumps when required will force a proportionate quantity of water to a greater height than fifty feet, upon which the following table is based:
Table of Approximate Dimensions and Capacities.
| Size Number | Gallons Per Hour 50 ft. | Size of Suc. & Dis. Pipes. | Approx. Floor Space | Height | Size of Smoke Pipe |
|---|---|---|---|---|---|
| 1 | 600 | 11⁄4″ | 43″ × 26″ | 53″ | 5″ |
| 2 | 1200 | 11⁄2″ | 43″ × 26″ | 58″ | 6″ |
| 3 | 2000 | 2″ | 48″ × 30″ | 63″ | 7″ |
| 4 | 3000 | 21⁄2″ | 48″ × 30″ | 63″ | 7″ |