Document zdqkvN0kRGnbEx4JrgkG58GaB

1014 CHAPTER 48 1952 Guide Table 1. Proper Flow and Pressure Required During Flow for Different Fixtures Fixtubb -,,Flow Pbebsubs* Flow gpm Ordinary basin faucet.................................................. Self-closing basin faucet...................................... Sink-faucet--| in............... ............................ Sink faucet--jin..-............................................ Bathtub faucet......... ................ Laundry tub cock--l in.................................................. Shower......................................... ....... Ball-cock for closet.............................................. Flush valve for closet.............. .................... Flush valve for urinal..................................................... Garden hose, 50 ft, and sill cock....................................... 8 12 10 5 5 \9. 15' 10-20 15 30 3.0 2.5 4.5 4.5 0 .*> n fi n 30 15-401- 15.0 5.0 ? Flow,pressure is the pressure in the pipe at the entrance to the particular fixture considered. Wide range due to variation in design and type of flush-valve closets. In general, a daily per capita water consumption of 40 gal can be iised'as a safe design figure for housing projects. Table 1 gives the rate of flow desirable for many common types of fixtures, and the average pressure necessary to give this rate of flow. The pressure necessarily varies with fixture design; with some, a much greater pressure is necessary to give the same rate of flow than with others. In general, the lower the quality of the faucet the greater will be the pressure required. ' In estimating theload, the rate of flow is .frequently computed in fixture units. One fixture unit is equivalent to 7.5 gal per min. Table 2 gives the demand weights in terms of fixture units for different plumbing fix tures under several conditions of service, and Fig. 1 gives the estimated demand in gallons per minute corresponding to any total number of fix ture units. Fig. 2 shows an enlargement of Fig. 1 for a range up to 250 fixture units. !: Table 2. Demand Weights of Fixtures in Fixture Units* Fixture os Group* Occupancy Type op Supply Control Weight in Fixture . Units? /. PfldMtfll urinal Stall or wall urinal Bathtub Kitchen , Water closet ... lavatory Water Services 1015 No. 1 for system predominantly for flush valves. No. 2 for system predominantly for flush tanks. Fio. 1. Estimate Curves for Demand Load- - The estimated demand load for fixtures used intermittently on any supply pipe will be obtained by multiplying the number of each kind of fixture supplied through that pipe by its weight from Table -2, adding the products, and .then referring to the appropriate curve of Figs. 1 or 2 ..to find the demand corresponding to the total fixture umts. In using . this, method it should be noted that , the demand for fixture or supply outlets other than those listed in the table of fixture umts is not yet in cluded in the estimate. The demands for outlets (such as hose connec tions, air conditioning apparatus, etc.) which are likely to impose con tinuous demand during times of heavy use of the weighted fixtures, should be estimated separately and added to the demand for fixtures used in termittently, in order to estimate the total demand. So far, the information presented possible the determination of the design rate of flow in any particular section of piping. The next gen eral step is to determine the size of piping. As water flows through a pipe, the pressure continually decreases along the pipe, due to loss of energy from friction. The problem is then pne of ascertaining the minimum pressure in the street .main, and the minimum Combination fixture Private________ Fauret 3 * For supply outlets likely to impose continuous demands, estimate continuous supply separately and add. to total demand for fixtures. b For fixtures not listed, weights may be assumed by comparing the fixture to a listed one ung water in similar quantities and at wimiW rates. 0 The given weights are for total demand. For fixtures with both hot and cold watersupplies, the weights for maximum separate demands may be taken as the listed demand for the supply. Fig. 2. Section of Fig. 1 on Enlarged Scale