Document RjRyy3MQMzwMX6zLO9BO9eera

950 CHAPTER 50 1949 Guide FRICTION LOSS IN HEAD IN LBS. PER SQ. IN. PER 100 FT. LENGTH Water Services 951 FRICTION LOSS IN HEAD IN LBS. PER SQ. IN. PER 166 FT. LENGTH Fio. 3. Flow Chart for Fairly Rough Pipe for disc-type meters, which may be regarded as the limits of recommended ranges in capacities, are given in Table 2. For information on other types of meters the manufacturers should be consulted. Estimated pressure losses for pipe fittings and valves in terms of equiva lent pipe length are shown in Table 3. The pressure loss, in pounds per square inch, caused by the difference in elevation between the street main and the highest fixture may be ob tained by multiplying the difference in elevation in feet by 0.43. Fig. 4. Flow Chart for Rough Pipe Example 1. Assume a minimum street main pressure of 55 psi; a height of topmost fixture above street main of 50 ft; a developed pipe length from water main to highest fixture of 100 ft; a total load on the system 50 fixture units; and that the water closets are flush-valve operated. Find the required size of supply main. , From Fig. 2 the estimated peak demand is found to be 51 gpm. From Table 2 it is. evident that several sizes of meters would adequately measure this flow. For a trial computation choose the 1 in. meter. From Fig. 6 the pressure drop through a 1}^ in. disc-type meter for a flow of 51 gpm is found to he 6.5 psi. ,, ' Then the pressure drop available for overcoming friction in pipes and fittings is 55 - (15 + 50 X 0.43 + 6.5) = 12 psi. ; j;