The diameter of the volute at the intake is 10 feet 6 inches, which decreases gradually along the spiral in proportion to the amount

of water flowing at different sectional areas. The height of the turbine is 30 feet, 22 feet wide, and weighs approximately 364,000 pounds.

The spiral casing permits the penstock to be received below the floor of the power-house, thus leaving room for oil switches under the switchboard gallery.

The guide vanes are operated by a vane ring, controlled by pistons from the cylinders. The area between the guides is regulated by the movement of this ring, and, therefore, the quantity of water entering the wheel per second is controlled.

The wheel is controlled by a Glocker-White mercurial hydraulic governor, and also a hydraulic hand-gear. The hydraulic cylinders at the top furnish power for moving the regulating apparatus.

The draught tubes from the wheel are of conical shape, designed so that the velocity of the water as it comes from the runner is decreased gradually until it is discharged into the tail-race. The velocity from the wheel and around the quarter turn is about 18 feet per second, while the velocity at the end of the draught tube as it enters the tail-race is about 3 feet per second, the draught tubes being gradually enlarged to 10 feet diameter at the ends in the tailrace. The head due to the velocity of the flowing water as it reaches the runners is about 4 feet. The draught tube was made a part of the turbine wheel and some of this 4 feet of head was regained by delivering the water in the tail-race at a velocity of 31⁄2 feet per second, with a corresponding velocity head of less than foot. The amount of head regained by the draught tubes would, theoretically, be the difference between the 4 feet and foot, or 3 feet. The efficiency of the draught tube is, however, only 50 to 80 per cent. so that the actual head regained is about 2 feet, and the efficiency is increased by the ratio of 2 feet to 135 feet, or 11⁄2 per cent.

The 10,500 horse-power is transmitted over long-distance electric lines 84 miles to Montreal, and there used for street-railways, electriclighting and general power purposes. The current is “stepped-up” at Shawinigan Falls from the 2,200 volt, quarter-phase, to 50,000 volts, three-phase, and carried to Montreal over three cables, each composed of seven No. 7 aluminum wires. At Montreal it is "steppeddown," with a loss in transmission of 18 per cent.

CHAPTER XIV

PUMPS AND PUMPING MACHINERY

CENTRIFUGAL PUMPS

CENTRIFUGAL force finds one of its most useful effects in the work

of the centrifugal pump.

=

Its measure of work is expressed by the formula

W V2

in which g R W the weight of a column of water 1 inch square and 1 foot deep or .434 of a pound. V2-velocity of the radius of gyration of solid disks or .7071 of the radius of the periphery of the wheel in feet per second. g=gravity or 32.16. R= radius of the periphery of the wheel.

Then for example, a pump of good design with a wheel 12 inches in diameter at 400 revolutions per minute, would have a peripheral velocity of

1256
60

20.94 feet per second and 20.94×.7071=14.8, the velocity of the radius or centre of gyration. The formula ex.434 X 14.82 95.06 pressed in figures will be 32.16X.5 16.08

=5.81 pounds per square

inch pressure, and the pressure X by 2.3 feet per pound = 13.36 feet total lift without overflow.

Below this head the pump will discharge inversely in proportion to the head and area of the pump and pipe connections. This corresponds with the tests of heads obtainable in practice, less the friction.

The action of compound and multiple centrifugal pumps multiplies the effect of a single pump in proportion to the number of units less the friction; they are constructed for any lift up to 1,000 feet.

There are many models of centrifugal pumps on the market, of which we illustrate enough to give a general idea of their various designs.

Fig. 243 shows Gwynne's centrifugal pump, which has six equi

distant pallets inclined backwardly toward their outer extremities. Three of these extend from the axis, and the remainder only from the margin of the annular induction-space around the axis. The wheel

rotates in a shell in the direction of the arrow, and delivers the water upward into the eduction-pipe L.

Fig. 244 shows the Golding volute pump. Four volute blades are attached to the shaft by arms. To the outer case are attached radial blades with their edges nearly touching the revolving volute blades. Suction at centre; discharge at sides of outside shells.

In Fig. 245 is shown a plan and section of the Wenzel pump. consisting of four spiral wings on a conical drum which act as a

FIG. 245.-Wenzel conical pump.

gradual feeder to the main wings at the large end of the

cone.

The two sets of wings or blades are inclined at opposite angles to counteract endthrust.

Andrew's centrifugal pump (Fig. 246) resembles a helix, cone placed with its axis in a

which forms the base of a double horizontal position, the space between the inner and outer cones being the chamber of the pump, and occupied by a turbine-wheel shown in the detached view E. F is the stationary boss with spiral flanges 7, which give the water a twist just as it enters upon the

action of the wheel. a is the base of the pump, cast in one piece with the case c, to which is attached by flanges the conducting-case, forming a spiral discharge-passage, gradually enlarging to the outlet f. A series of grooves, which are fitted in a Babbitt metal box in the standard h, counteracts any tendency to endthrust.

Fig. 247 shows a section of a disk pump of German type. The revolving disk receives the water on each side near the shaft in curved channels, and discharges through openings in the

periphery of the disk opposite to a continued slot in the casing. A corrugated closure of the shell and disk near the shaft prevents back flow of the water escaping over the periphery of the disk, thereby adding to the efficiency of this class of pumps.

FIG. 247. Single-disk pump.

In Fig. 248 is shown a section of the Worthington multistage turbine pump of three stages. In their design they are balanced for longitudinal thrust and their propelling power largely augmented by a series of diffusion vanes at the periphery of each impeller to check the tangential motion of the water and feed it radially to the next impeller under pressure.

In Fig. 249 is shown a section of a four-stage centrifugal pump, design of T. Reuter and made in Switzerland. The thrust balance is obtained by placing two impellers in each section together, so that their thrust pressure sides are opposite to each other, thus balancing the shaft-thrust. The