NOTE.—There seems to be no form of water pipe so perfect as to make it fit for use in any and all cases and open to no improvement, but, in the present state of knowledge, tarred cast iron seems to come the nearest to this desideratum.
TABLE SHOWING FRICTIONAL HEADS AT GIVEN RATES OF DISCHARGE IN CLEAN CAST IRON PIPES FOR EACH 1000 FEET OF LENGTH, CONDENSED FROM ELABORATE TABLES PREPARED BY MESSRS. GEO. A. ELLIS AND A. H. HOWLAND, CIVIL ENGINEERS, BOSTON, MASS.
------------+------------+-----------------------+----------------------- U.S. gallons|U.S. gallons| 16-INCH PIPE. | 18-INCH PIPE. discharged | discharged +-----------------------+--------+-------------- per minute.| per twenty-|Velocity| Friction |Velocity| Friction | four hours.| in | Head. | in | Head. | | feet. +------+-------+ feet. +------+------- | | |Feet. |Pounds.| |Feet. |Pounds. ------------+------------+--------+------+-------+--------+------+------- 500 | 720000 | .80 | .22 | .09 | .63 | .13 | .06 1000 | 1440000 | 1.60 | .76 | .34 | 1.26 | .44 | .19 1500 | 2160000 | 2.39 | 1.63 | .71 | 1.89 | .93 | .40 2000 | 2880000 | 3.19 | 2.82 | 1.22 | 2.52 | 1.60 | .69 2500 | 3600000 | 3.99 | 4.34 | 1.88 | 3.15 | 2.45 | 1.06 3000 | 4320000 | 4.79 | 6.19 | 2.68 | 3.78 | 3.48 | 1.51 3500 | 5040000 | 5.59 | 8.37 | 3.63 | 4.41 | 4.70 | 2.03 4000 | 5760000 | 6.38 |10.87 | 4.71 | 5.04 | 6.09 | 2.64 4500 | 6480000 | 7.18 |13.70 | 5.93 | 5.67 | 7.67 | 3.32 5000 | 7200000 | 7.98 |16.85 | 7.30 | 6.30 | 9.43 | 4.08 5500 | 7920000 | 8.78 |20.33 | 8.71 | 6.93 |11.38 | 4.92 6000 | 8640000 | ... | ... | ... | 7.57 |13.49 | 5.84 ------------+------------+--------+------+-------+--------+------+-------
------------+------------+-----------------------+----------------------- U.S. gallons|U.S. gallons| 20-INCH PIPE. | 24-INCH PIPE. discharged | discharged +--------+--------------+--------+-------------- per minute.| per twenty-|Velocity| Friction |Velocity| Friction | four hours.| in | Head. | in | Head. | | feet. +------+-------+ feet. +------+------- | | |Feet. |Pounds.| |Feet. |Pounds. ------------+------------+--------+------+-------+--------+------+------- 500 | 720000 | .51 | .08 | .04 | .35 | .04 | .02 1000 | 1440000 | 1.02 | .27 | .12 | .71 | .12 | .05 1500 | 2160000 | 1.53 | .56 | .24 | 1.06 | .24 | .10 2000 | 2880000 | 2.04 | .96 | .42 | 1.42 | .41 | .18 2500 | 3600000 | 2.55 | 1.47 | .64 | 1.77 | .62 | .27 3000 | 4320000 | 3.06 | 2.09 | .90 | 2.13 | .87 | .38 3500 | 5040000 | 3.57 | 2.81 | 1.22 | 2.48 | 1.16 | .50 4000 | 5760000 | 4.08 | 3.64 | 1.58 | 2.84 | 1.50 | .65 4500 | 6480000 | 4.59 | 4.58 | 1.98 | 3.19 | 1.88 | .82 5000 | 7200000 | 5.11 | 5.62 | 2.43 | 3.55 | 2.31 | 1.00 5500 | 7920000 | 5.62 | 6.77 | 2.93 | 3.90 | 2.77 | 1.20 6000 | 8640000 | 6.13 | 8.03 | 3.48 | 4.26 | 3.28 | 1.42 7000 | 10080000 | 7.15 |10.86 | 4.71 | 4.96 | 4.43 | 1.92 8000 | 11520000 | ... | ... | ... | 5.67 | 5.75 | 2.49 9000 | 12960000 | ... | ... | ... | 6.38 | 7.25 | 3.14 ------------+------------+--------+------+-------+-------+--------+------