CAST-IRON SOCKET-PIPES FOR WATER. Pipes should be cast from good grey metal, twice run, of such quality that a bar of the same 2 inches deep × 1 inch thick placed upon supports 3 feet apart will not break with a less load than from 28 to 30 cwt. suspended at the centre, which weight will cause a deflection of about inch. Strength of Metal. The tenacity of the cast-iron of which pipes are usually made, averages 15000 lbs. per square inch, which divided by the factor of safety, 6, gives a working strength of 2500 lbs. per square inch. Thickness of Metal of Pipes.-Besides making the thickness sufficient to bear the water pressure, allowance must be made for hydraulic shocks due to the closing of cocks, &c., as well as for the strain due to weights falling upon, or passing over them after they are laid underground; the following two rules are used by makers of water-pipes, both of which give good and nearly the same results. Rule 1.-Multiply the internal diameter of the pipe in inches by the working head in feet, divide the product by 10,000, and add the constant number, 30, to the result, which will give the thickness of metal (cast-iron) in inches. Rule 2.-Multiply the working pressure in lbs. per square inch by the internal radius of the pipe in inches, and divide the product by the working strength of the metal 2500, then add the constant number 30 to the result, which will give the thickness of the metal of the pipe in inches; this constant number is added for the allowance to be made for shocks, &c., mentioned above, and may be varied to suit circumstances. The Depth of Socket is varied a little by different iron founders; a good proportion is to make the inside depth according to the following rule. Multiply the internal diameter of the pipe by 13, and add the constant number 3 to the result. The space for the lead joint should be inch for small pipes, inch for medium-sized pipes, inch for large pipes, and inch for very large pipes. Testing Pipes.-Pipes should be tested to double their working pressure-but not beyond that-otherwise the metal is liable to be strained and weakened; and, while under pressure, they should be struck moderately hard with a hammer to represent the shocks they will be subject to after being laid underground. Deviation in thickness and weight.-A deviation in thickness of inch for small, and inch for medium sized, and for large sizes, is sometimes permitted, and a deviation in weight of about 1 lb. per inch in diameter is permitted. Weight of Socket-Pipes.—The weights of ordinary sizes of pipes for water are given in Table 13. The first two sizes are suitable for a working head of 100 feet water pressure, the 1 to 9-inch pipes are suitable for 150 feet water-pressure, and the pipes above that size are suitable for a working head of 300 feet water-pressure the proof strain being double these quantities. TABLE 13.-WEIGHT OF ORDINARY SIZES OF CAST-IRON SOCKET-Pipes. NOTE.-The Length does not include the Length of the Socket, but the Weight includes that of the Socket. Table 14.-WEIGHT OF ORDINARY STOCK SIZES OF CAST-IRON FLANGEPIPES FOR WAter, proved tO THE SAME WATER PRESSURE AS THE SOCKET PIPES GIVEN IN TABLE 13. Size inside Diameter. Length Thickness Diameter Thickness Number Diameter of circle | Average Weight of Pipe. of Metal. of Flange. of Flange. of Bolts. of Bolts. of Centre of Pipe. of Bolts. Feet. Inches. Inches. Inches. Bolts. Inches. Inches. 6 O cwt. qr. lb. I 6 O о I 16 I 18 о 2 13 I 5 16 11 I O 22 Inches. 1816 45677 GO ON 9 ΙΟ II 12 Table 15.-WEIGHT OF EXTRA STRONG CAST-IRON FLANGE-PIPES. Weight of Pipes and Cylinders. A simple rule to find the weight of pipes and cylinders of cast-iron is:-From the square of the outside diameter subtract the square of the inside diameter in inches, multiply the result by 7 and divide that product by 3, which will give the weight in lbs. approximately of one foot in length of the pipe. To find the exact weight, use 7:4 as a multiplier instead of 7 given above. To find the weight of pipes and cylinders of other metals, multiply the result found by the above rule by 105 for wrought iron; 108 for steel; 12 for gun metal; 115 for brass; 121 for copper; 1004 for tin; 156 for lead; and by 988 for zinc. Contents of Pipes.-To find the number of gallons contained in a circular pipe, multiply the square of the diameter in inches by 034; the product will be the contents in gallons in a foot length of pipe. To find the weight of water in lbs. in a circular pipe 1 foot long, square the diameter in inches and multiply the result by 34. To find the weight of water in lbs. in a pipe 3 feet long, square the diameter in inches. Thickness of Cast-Iron Gas-Pipes. The thickness of metal given in Table 13 for water pipes, is also suitable for gas pipes up to 6 inches diameter, but above that size, the thickness is too great for pipes for this purpose, and the correct thickness of metal for cast-iron gas-pipes may be obtained by multiplying the thickness given in that Table by 86 for cast-iron pipes of from 7 to 13 inches diameter. 76 '70 Do. Do. Do. Table 16.-SHEWING THE CONTENTS IN GALLONS AND WEIGHT IN LBS. of WATER IN PIPES AND WELLS I FOOT IN DEPTH. To find the pressure in lbs. per square inch of water in pipes, multiply the head of water in feet by 443. Table 17.-SHEWING THE PRESSURE IN PIPES WITH VARIOUS Injectors for Feeding Boilers.-For the average temperature of feed and height of lift of ordinary injectors, the quantity of water delivered in gallons per hour by an ordinary injector feeding the boiler from whence its steam supply is derived, may be found by Mr. Hey's rule. Multiply the square of the diameter of the injector nozzle in millimetres by the square root of the pressure of the steam in lbs. per square inch, and multiply the product by the constant number 2. WATER WHEELS. The Driving Power of flowing water being gravity, the power exerted by a weight of water falling from a given height is equal to the product of the weight of water in lbs., and the height of the fall in feet. But, in driving a waterwheel, a percentage of the power is absorbed by friction, by overcoming the resistance of the waterwheel, and by the loss due to leakage. The efficiency or power given out varies from 30 to 75 per cent. of the power of the water, according to the class of waterwheel employed. A horsepower being 33,000 lbs. raised one foot high in a minute, or 550 foot lbs. per second, the theoretical force in a fall of water is found thus:-Multiply the weight of a cubic foot of water, 624 lbs., by the number of cubic feet falling per second; multiply that product by the height of the fall in feet, and divide the result by 550; the quotient will be the available theoretical horse power of that fall. Overshot Water-wheels. The water is generally laid on this class of wheel at a little below the top of the wheel from the side at which it approaches. The current of water being reversed in the pentrough, it is called a pitch-back wheel; diameter of wheel from 1 to 1 the height of fall; speed of the circumference 4 to 5 feet per second; efficiency from 60 to 70 per cent. of the waterpower expended. High-Breast Water-wheel. The water is laid on to this class of wheel about 27° from the top; diameter of wheel 1 times the height of the fall; speed of the circumference 5 feet per second; efficiency 75 per cent. of the waterpower expended. Breast Water-wheel. The water is laid on to this class of wheel a little below the level of its axis; diameter of wheel equal to about twice the height of fall; speed of the circumference from 5 to 6 feet per second; efficiency from 55 to 60 per cent. of the waterpower expended. Undershot Water-wheels with radial floats are used when the fall is under 5 feet; diameter of wheel from 12 to 20 feet; speed of the circumference 50 of the velocity of the water; efficiency from 25 to 33 per cent. of the waterpower expended. Paddle Water-wheel.-Wheels of this class are fixed on boats moored in an open current; diameter of wheel from 14 to 20 feet; speed of the |