The accompanying diagram shows the general arrangement of the automatic electric house system used with a tank in the upper part of the building and the pump in the basement or cellar. The operation is as follows:
When water is being delivered to the tank, the float rises until the upper knob makes forcible contact with the switch lever, opening the switch and stopping the pump. When water is withdrawn from the tank, the float falls until the lower knob makes contact with the switch lever, which again closes the switch and starts the pump. The supply of water is thus maintained within the tank without the aid of an attendant. The accompanying illustration, [Fig. 238], shows a Worthington house tank pump of 500 gallons per hour capacity belted to a General Electric direct current motor, the pump and motor being mounted on the same base.
Table of Capacity.
| Diameter of Plungers | Length of Stroke | Revolutions per Minute | Gallons per Minute | Maximum Water Pressure in Lbs. | Gallons per Hour | Feet 1 H.P. Will Pump Against | Feet 2 H.P. Will Pump Against |
|---|---|---|---|---|---|---|---|
| 2 | 4 | 45 | 9.8 | 150 | 500 | 175 | 300 |
| 23⁄4 | 4 | 45 | 18.5 | 75 | 1,000 | 80 | 175 |
| 3 | 4 | 45 | 21.8 | 60 | 1,200 | 70 | 140 |
| 33⁄4 | 4 | 45 | 34.4 | 40 | 1,800 | 50 | 100 |
The above useful table is inserted to show the capacities, revolutions, size of plungers, etc., in these electrically driven pumps, the automatic feature of which is truly admirable.
It must be remembered that the number of combinations between small electric motors and proportionate pumps for water, gas, air, etc., afford an endless field for the exercise of engineering skill.
ELECTRIC MOTOR AND AIR PUMP.
[Fig. 240] is intended to show the application of the electric motor to a triplex pump of small size, the plungers being 31⁄8 inches in diameter. The Stroke is 47⁄8 inches which gives a capacity of 108 cubic inches per revolution, with a pressure of 50 lbs. to the square inch. The pumps require about one-half horse power applied at the motor.