Determine the service water demand for each fixture in fixture units (FU), and then find the...

 

 

 

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Determine the service water demand for each fixture in fixture units (FU), and then find the total demand in fixture units. • Determine the required flow rate to the building. • The demand weights in terms of fixture units for different plumbing fixtures under several conditions of service are given in Table 25; • The estimated demand corresponding to any total number of fixture units is given in Figure 9; • More accurate estimates at the lower end of the scale are provided in Figures 10 and 11. . Determine the equivalent length of pipe in the main line of the building. • For initial estimate of fitting losses, a frequently used rule of thumb assumes the design length of pipe as 50 to 100% longer than actual; • Select a pipe size for the desired total flow rate and available/allowable pressure drop as per the above; • As the exact equivalent length of the various fittings cannot be determined as the pipe sizes are not yet known, a first approximation is necessary to tentatively select pipe sizes; • Determine the average minimum pressure in the street main and the minimum pressure required for the topmost fixture operation, which should be 50 to 175 kPa above atmospheric; •Determine the approximate design pressure drop per unit length (kPa/m). Ap = [Ps - (9.8 H + Pf+ Pm)] / TEL Ap = [9.8 H- (Pf + Pm)]/TEL • Determine the pipe sizes of the main line. • choose the sizes of pipe from Figures 14 (steel), 15 (copper), or 16 (plastic) • Determine the pipe sizes of one typical branch (Highlight the branch you performed your calculations on). • Make sure that the velocity in pipes are between 1.2 and 3 m/s, if not modify your system to overcome that. Fig. 10 Estimate Curves for Demand Load (Adapted from Hunter 1941) Fig. 9 Demand Versus Fixture Units, Mixed System, High Part of Curve (Adapted from Hunter 1941) The area = 14*70 14 Floors DEMAND, L/s 30 25 20 15 10 5 0 0 0 (2) 500 No. 1 for system predominantly for flush valves. No. 2 for system predominantly for flush tanks. 1000 1500 2000 FIXTURE UNITS 2500 Fig. 10 Estimate Curves for Demand Load (Adapted from Hunter 1941) 3000 DEMAND Q, L/s 105 100 95 90 85 80 75 70 0 65 60- 55 50 45 40- 35 30 25- 20 15 10- 5- 2 3 Fig. 9 7 8 9 10 11 12 13 14 15 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 FIXTURE UNITS (THOUSANDS) 205 200 195 190 185 180 175 170 165 -160 5 155 150 145 140 135 130 125 -120 115 110 105 100 Demand Versus Fixture Units, Mixed System, High Part of Curve (Adapted from Hunter 1941) DEMAND Q, Lis D Determine the service water demand for each fixture in fixture units (FU), and then find the total demand in fixture units. • Determine the required flow rate to the building. • The demand weights in terms of fixture units for different plumbing fixtures under several conditions of service are given in Table 25; • The estimated demand corresponding to any total number of fixture units is given in Figure 9; • More accurate estimates at the lower end of the scale are provided in Figures 10 and 11. . Determine the equivalent length of pipe in the main line of the building. • For initial estimate of fitting losses, a frequently used rule of thumb assumes the design length of pipe as 50 to 100% longer than actual; • Select a pipe size for the desired total flow rate and available/allowable pressure drop as per the above; • As the exact equivalent length of the various fittings cannot be determined as the pipe sizes are not yet known, a first approximation is necessary to tentatively select pipe sizes; • Determine the average minimum pressure in the street main and the minimum pressure required for the topmost fixture operation, which should be 50 to 175 kPa above atmospheric; •Determine the approximate design pressure drop per unit length (kPa/m). Ap = [Ps - (9.8 H + Pf+ Pm)] / TEL Ap = [9.8 H- (Pf + Pm)]/TEL • Determine the pipe sizes of the main line. • choose the sizes of pipe from Figures 14 (steel), 15 (copper), or 16 (plastic) • Determine the pipe sizes of one typical branch (Highlight the branch you performed your calculations on). • Make sure that the velocity in pipes are between 1.2 and 3 m/s, if not modify your system to overcome that. Fig. 10 Estimate Curves for Demand Load (Adapted from Hunter 1941) Fig. 9 Demand Versus Fixture Units, Mixed System, High Part of Curve (Adapted from Hunter 1941) The area = 14*70 14 Floors DEMAND, L/s 30 25 20 15 10 5 0 0 0 (2) 500 No. 1 for system predominantly for flush valves. No. 2 for system predominantly for flush tanks. 1000 1500 2000 FIXTURE UNITS 2500 Fig. 10 Estimate Curves for Demand Load (Adapted from Hunter 1941) 3000 DEMAND Q, L/s 105 100 95 90 85 80 75 70 0 65 60- 55 50 45 40- 35 30 25- 20 15 10- 5- 2 3 Fig. 9 7 8 9 10 11 12 13 14 15 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 FIXTURE UNITS (THOUSANDS) 205 200 195 190 185 180 175 170 165 -160 5 155 150 145 140 135 130 125 -120 115 110 105 100 Demand Versus Fixture Units, Mixed System, High Part of Curve (Adapted from Hunter 1941) DEMAND Q, Lis D

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