183. Improved Turbine.
Turbines are a form of water motor which require a head of water, i.e. the water for propelling them must be supplied by means of pipes from a height; for a moderate power, with the majority of turbines, it should be not less than 12 ft.; the higher the head of water the greater the pressure, and the smaller the turbine requires to be for a given amount of work or power (this applies to all water motors), consequently the cost of the motor is less, the pipes smaller, and there is decided economy in the quantity of water used as the height increases. The pressure of water in pipes is 1 lb. to the square inch for every 2 ft. 4 in. in height (not allowing for friction); thus it will be seen that the surface in a turbine upon which the pressure of water is exerted, requires to be double the area with a 20 ft. fall than with a 40 ft. fall for given power. A Warner’s 5 horse-power turbine for 16 ft. fall uses 220 ft. of water per minute with a wheel of 13 in. diameter, giving 377 revolutions a minute, and costing 60l., whereas a 5 horse-power turbine for 30 ft. fall uses 118 ft. of water with an 8 in. wheel giving 853 revolutions a minute and costs 45l. Fig. 183 shows a Warner’s (Redtenbacher Jouval) improved turbine fitted and connected to a driving shaft. This turbine is made to work with as low a fall as 2 ft., giving 1 horse-power, but the cost is necessarily high. It will be seen from the illustration (which is in section), that the water is made to pass between fixed oblique blades or palettes, and strikes on the oblique blades of the wheel beneath, these latter blades being at an opposite angle to the fixed blades above; thus a pressure, varying with the height of head of water, is directly exerted on every square inch of the blades of the wheel and great power is obtained.
184. Blake’s Ram.
Hydraulic Rams are self-acting water motors, for the supply of water to great heights and distances; they require a fall of water of 12 in. upwards, and are made to supply either the water that works them, or to supply well water while being worked by a stream of impure water; one of the best makers and authorities upon these motors is John Blake, of Oxford Street Works, Accrington, Lancashire. Fig. 184 shows a Blake’s ram of ordinary construction, for raising a portion of the water that works it; a No. 2 (smallest size), price 12l., will raise 300 gal. per day, to say 800 ft. high; a No. 16 will raise 100,000 gal. per day. Fig. 185 shows a ram raising water to a reservoir for general purposes.
185. Blake’s Ram in use. 186. Haag’s Motor.
A hydraulic ram is undoubtedly the most economical means of raising a supply of water, either for a single residence or for a small town, as they work day and night without attention (or intermittently if desired), and work as well submerged as above water; but they, of course, depend entirely upon a fall of water being obtainable, and this fall or supply must be constant.