34 
BULLETIN 894, U. S. DEPARTMENT OF AGRICULTURE. 
For all bends, globe valves, or similar obstructions, consider the 
length, of the pipe increased as follows: Right angle elbows, 40 
diameters; tees, 45 diameters; globe valves, 60 diameters. Mixing 
valves will reduce the pressure from 2 to 5 pounds. For pipes hav- 
ing an equivalent pipe length over or under 100 feet, interpolate for the 
loss in pressure in proportion to the length. 
10 000 
«~ «MTOrr(oeoo ooo 
FRICTION PRESSURE LOSS LBS. PER SQ. IN. PER 100 FT. 
Fig. 10. 
SIZE OF WATER MAINS. 
The water main should be gradually increased in size as it ap- 
proaches the source of supply in proportion to the amount of 
water required to supply the kilns. To determine the size at any 
given point, calculate the amount of water required in the kilns 
between that point and the end of the line away from the source of 
