Usual inclination of pipes.

1

in.

in

12 ft.

= minimum fall for house drains;

1

"

"

16 "

= minimum fall for land drains;

1

"

"

40 "

= minimum fall for sub-drains for houses;

1

"

"

100 "

= minimum fall for main drains for houses;

1

"

"

150 "

=fall of mountain torrents;

1

"

"

230 "

= " " rivers and rapid currents;

1

"

"

280 "

= fall of strong currents;

1

"

"

340 "

= " " ordinary rivers with good current;

1

"

"

440 "

= fall of winding rivers subject to inundations with slow current;

1

"

"

480 "

= fall of water channels, supply pipes to reservoirs and small canals;

1

"

"

570 "

= fall of large canals;

1

"

"

1,000 "

= very slow current, approaching to stagnant water.

Discharge through pipes.

Discharge in 24 hours divided by 1,440 = discharge per min.; discharge in cubic feet per minute X 9,000 = imperial gallons per day of 24 hours; discharge in cubic feet per minute X 11,000 = U. S. gallons per day of 24 hours; discharge in cubic feet per second X 2.2 = cubic yards per minute; discharge in cubic feet per second X 6.24 =imperial gallons per second; discharge in cubic feet per second X 7.48 = U. S. gallons per second; discharge in cubic feet per second X 133 = cubic yards per hour; discharge in cubic feet per second X 375 = imperial gallons per minute; discharge in cubic feet per second X 450 == U. S. gallons per minute; discharge in cubic feet per second X 2,400 = long tons per day of 24 hours; discharge in cubic feet per second X 2,700 = short tons per day of 24 hours; velocity in feet per second X 0.68= mile per hour; velocity in feet per second X 60 = feet per minute; velocity in feet per second X 20 = yards per minute; pressure head of water in feet = pressure of water in lbs. per square foot X 0.016; pressure of water in lbs. per square foot = head in feet X 62.32.