Document x04d0Ly30JKGLvqgpGnyY4q0

1100 CHAPTER 49 1955 FRICTION LOSS IN HEAD IN LBS. PER SQ. IN. PER 100 FT. LENGTH ^ ater Services 1101 Fig. 6. Pressure Losses in Water Meters pounds per square inch for any given rate of flow. Experience has shown, however, that the simplest method of expressing losses in fittings and valves is to use the concept of an equivalent length of straight pipe. Thus it has been found, for example, that a 1 in., 90 deg elbow introduces a loss equivalent to 2.2 ft of straight 1 in. pipe. Therefore, for each 1 in., 90 deg elbow, 2.2 ft of 1 in. pipe are added to the total length of 1 in. pipe. Estimated pressure losses for pipe fittings and valves in terms of equiva lent pipe length are shown in Table 4. Table 5 lists the equivalent lengths for various special types of ap paratus and fittings. The loss in water meters varies considerably with the design even in meters of the same nominal size. The values given in Table 5 are ample for the well-known meters now on the market. Fig. 5. Flow Chart fob Rough Pipe Solution: Enter Fig. 4 at 100 gpm, and move along this line until it intersects the 2$ in. diameter line. From this intersection point, move vertically down and read 4.5 psi friction loss per 100 ft of pipe length. Then the total friction loss will be 2 x 4.5 = 9 psi. The pressure losses in the distributing system will consist of the pressure losses in the piping itself, plus the pressure losses in the pipe fittings, valves and the water meter, if any. Estimated pressure losses for disc-type meters for various rates of flow are given in Fig. 6. Flow limits for disc-type meters, which may be regarded as the limits of recommended ranges in capacities, are given in Table 3. For informa tion on other types of meters, the manufacturers should be consulted. Fig. 7 shows the variation of pressure loss with rate of flow for various types of faucets and cocks, based on experimental data obtained at tbe State University of Iowa. The loss of pressure through any fitting or valve can be expressed m and Cocks r . m- laundry bibb (old style). E. Combination compression sink faucet sundry compression faucet. F. Basin faucet. | !n* compression sink faucet (Mfr. 1). G. Spring self-closing fauoet. D p' ln-.compression sink fauoet (Mfr. 2).. H. Slow self-closing faucet. * ^-'ombination compression bath tub faucets (both open). (Dashed lines indicate recommended extrapolation)