Technology in Architecture Lecture 13 Upfeed Systems Pipe Sizing Procedure Pipe Sizing Example

Upfeed Systems

Pressure in Upfeed Systems Fixture pressure head Static head Friction head loss Meter pressure loss M: p. 858, F.19.13

Pressure in Upfeed Systems Proper fixture flow pressure A + Pressure lost due to height B + Pressure lost due to friction C + Pressure lost through meter D Total street main pressure E

A: Fixture Flow Pressure Pressure needed to get water through fixture M: p. 916, T.19.14

B: Pressure lost due to height Weight of water column M: p. 858, F.19.13

C: Pressure loss due to friction Initially unknown, must be calculated based on pressure remaining after accounting for the other factors

D: Pressure lost through meter Make initial size assumption and then repeat to optimum size M: p. 917, F.19.63

E: Total Street Main Pressure Check with water company or fire department

Pipe Sizing Procedure

1. Determine Supply Fixture Units Fixture units take into account usage diversity M: p. 919, T.19.15

2. Calculate Demand Flow Use curve 1 for flush valve dominated system Use curve 2 for flush tank dominated systems M: p. 919, F.19.65

3. Determine the “Most Critical Fixture (MCF)” Highest and farthest from inlet main Confirm pressure required (A) Identify height (B) M: p. 903, F.19.52

4. Determine Developed Length The total length of all horizontal and vertical pipes from the main to the MCF M: p. 941, F.20.17

5. Determine Total Effective Length (TEL) Two approaches: 1. equivalent length or 2. multiply DL x 1.5 TEL= DL x 1.5 M: p. 920, T.19.16a

6. Determine Street Main Pressure (E) Contact utility company or fire department

7. Determine Pressure Available for Friction Loss Proper fixture flow pressure A + Pressure lost due to height B + Pressure lost due to friction C + Pressure lost through meter D Total street main pressure E or C=E-A-B-D

Meter Loss (D) Since D is unknown, pick an initial size, do calculation, repeat as needed to optimize flow C=E-A-B-D M: p. 917, F.19.63

8. Determine Friction loss/100’ C=E-A-B-D Δp/100’ = 100 x C/TEL

9. Verify flow for meter size If flow > Total Demand (#2)  repeat 7-9 at smaller diameter If flow < Total Demand (#2)  repeat 7-9 at larger diameter M: p. 918, F.19.64

10. Select final meter size When flow > Total Demand (#2)  stop M: p. 918, F.19.64

Pipe Sizing Example

Given Information Small Office Building  public numbers 2 Flush valve toilets 2 Lavatories 2 Drinking fountains 1 Service sink DL: 92’ MCF: Flush Valve Toilet, 16’ above water main Street Main Pressure: 64.1 psi

1. Determine Supply Fixture Units Fixture units take into account usage diversity M: p. 919, T.19.15

1. Determine Supply Fixture Units Cold Hot Total 2 Flush valve toilets 20.00 --- 20.0 2 Lavatories 3.00 3.00 4.0 2 Drinking fountains 0.50 --- 0.5 1 Service sink 2.25 2.25 3.0 25.75 5.25 27.5

2. Calculate Demand Flow 20 WSFU out of 27.5 WSFU are flush valves Use curve 1 for flush valve dominated system 40 gpm M: p. 919, F.19.65

3. Determine the Most Critical Fixture Confirm pressure required (A) 35 psi Height above main (B) 16’  7.0 psi M. p. 916, T.19.14

4. Determine Developed Length 92’ Note: this figure for generic reference only and does not illustrate the example problem M: p. 941, F.20.17

5. Determine Total Effective Length (TEL) TEL= DL x 1.5 = 92 x 1.5 = 138’

6. Determine Street Main Pressure (E) 64.1 psi

7. Determine Pressure Available for Friction Loss Proper fixture flow pressure A 35.0 + Pressure lost due to height B 7.0 + Pressure lost due to friction C ? + Pressure lost through meter D ? Total street main pressure E 64.1

Meter Loss (D) Pick an initial size 2” diameter… 1.4 psi M: p. 917, F.19.63

8. Determine Friction loss/100’ C=E-A-B-D = 64.1-35.0-7.0-1.4 = 20.7 psi Δp/100’=100 x 20.7/138 = 15 psi/100’

9. Verify flow for meter size At 2” Flow=150 gpm > Total Demand 40 gpm At 1-1/2” Flow=60 gpm > (Δp/100’= 13.1) At 1” Flow=13 gpm < (Δp/100’= 5.1) M: p. 918 F.19.64

9. Verify flow for meter size When flow > Total Demand (#2)  stop At 1-1/2” Flow=60 gpm > Total Demand 40 gpm (Δp/100’= 13.1) M: p. 918 F.19.64

Pipe Sizing Use Δp/100’= 13.1 psi/100’ Use fixture units to determine flow M: p. 918 F.19.64

Pipe Sizing Use fixture units to determine flow Pay attention to flush valve domination M: p. 919 F.19.65

Pipe Sizing Use Δp/100’= 13.1 psi/100’ Use fixture units to determine flow Select size which does not exceed 13.1 psi/100’ 20 gpm, use 1” 10 gpm, use ¾” Use runout sizes at each fixture M: p. 918, F.19.64

Runout Pipe Sizing Use actual flow to size runouts Lavatory: 2 gpm M: p.916, T.19.14

Runout Pipe Sizing Use Δp/100’= 13.1 psi/100’ Lavatory: 2 gpm M: p. 918, F.19.64

Notation System Suggested for organizing data WSFU Curve Flow Diam. 2.7 2 3 ½” 3.6 2 4 ¾” M: p. 941, F.20.17