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P2903.6 Determining Water Supply Fixture Units
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CONVERSIONS FROM WATER SUPPLY FIXTURE UNIT TO GALLON PER MINUTE FLOW RATES
Supply loads in the building water distribution system shall be determined by total load on the pipe being sized, in terms of water supply fixture units (w.s.f.u.), as shown in Table P2903.6, and gallon per minute (gpm) flow rates [see Table P2903.6(1)]. For fixtures not listed, choose a w.s.f.u. value of a fixture with similar flow characteristics.
TABLE P2903.6
WATER SUPPLY FIXTURE UNIT VALUES FOR VARIOUS PLUMBING FIXTURES AND FIXTURE GROUPS
| TYPE OF FIXTURES OR GROUP OF FIXTURES | WATER-SUPPLY FIXTURE-UNIT VALUE (w.s.f.u.) | ||
| Hot | Cold | Combined | |
| Bathtub (with/without overhead shower head) | 1.0 | 1.0 | 1.4 |
| Clothes washer | 1.0 | 1.0 | 1.4 |
| Dishwasher | 1.4 | — | 1.4 |
| Full-bath group with bathtub (with/without shower head) or shower stall | 1.5 | 2.7 | 3.6 |
| Half-bath group (water closet and lavatory) | 0.5 | 2.5 | 2.6 |
| Hose bibb (sillcock)a | — | 2.5 | 2.5 |
| Kitchen group (dishwasher and sink with or without food-waste disposer) | 1.9 | 1.0 | 2.5 |
| Kitchen sink | 1.0 | 1.0 | 1.4 |
| Laundry group (clothes washer standpipe and laundry tub) | 1.8 | 1.8 | 2.5 |
| Laundry tub | 1.0 | 1.0 | 1.4 |
| Lavatory | 0.5 | 0.5 | 0.7 |
| Shower stall | 1.0 | 1.0 | 1.4 |
| Water closet (tank type) | — | 2.2 | 2.2 |
For SI: 1 gallon per minute = 3.785 L/m.
- The fixture-unit value 2.5 assumes a flow demand of 2.5 gallons per minute, such as for an individual lawn sprinkler device. If a hose bibb or sill cock will be required to furnish a greater flow, the equivalent fixture-unit value may be obtained from this table or Table P2903.6(1).
| SUPPLY SYSTEMS PREDOMINANTLY FOR FLUSH TANKS | SUPPLY SYSTEMS PREDOMINANTLY FOR FLUSHOMETER VALVES | ||||
| Load | Demand | Load | Demand | ||
| (Water supply fixture units) | (Gallons per minute) | (Cubic feet per minute) | (Water supply fixture units) | (Gallons per minute) | (Cubic feet per minute) |
| 1 | 3.0 | 0.04104 | — | — | — |
| 2 | 5.0 | 0.0684 | — | — | — |
| 3 | 6.5 | 0.86892 | — | — | — |
| 4 | 8.0 | 1.06944 | — | — | — |
| 5 | 9.4 | 1.256592 | 5 | 15.0 | 2.0052 |
| 6 | 10.7 | 1.430376 | 6 | 17.4 | 2.326032 |
| 7 | 11.8 | 1.577424 | 7 | 19.8 | 2.646364 |
| 8 | 12.8 | 1.711104 | 8 | 22.2 | 2.967696 |
| 9 | 13.7 | 1.831416 | 9 | 24.6 | 3.288528 |
| 10 | 14.6 | 1.951728 | 10 | 27.0 | 3.60936 |
| 11 | 15.4 | 2.058672 | 11 | 27.8 | 3.716304 |
| 12 | 16.0 | 2.13888 | 12 | 28.6 | 3.823248 |
| 13 | 16.5 | 2.20572 | 13 | 29.4 | 3.930192 |
| 14 | 17.0 | 2.27256 | 14 | 30.2 | 4.037136 |
| 15 | 17.5 | 2.3394 | 15 | 31.0 | 4.14408 |
| 16 | 18.0 | 2.90624 | 16 | 31.8 | 4.241024 |
| 17 | 18.4 | 2.459712 | 17 | 32.6 | 4.357968 |
| 18 | 18.8 | 2.513184 | 18 | 33.4 | 4.464912 |
| 19 | 19.2 | 2.566656 | 19 | 34.2 | 4.571856 |
| 20 | 19.6 | 2.620128 | 20 | 35.0 | 4.6788 |
| 25 | 21.5 | 2.87412 | 25 | 38.0 | 5.07984 |
| 30 | 23.3 | 3.114744 | 30 | 42.0 | 5.61356 |
| 35 | 24.9 | 3.328632 | 35 | 44.0 | 5.88192 |
| 40 | 26.3 | 3.515784 | 40 | 46.0 | 6.14928 |
| 45 | 27.7 | 3.702936 | 45 | 48.0 | 6.41664 |
| 50 | 29.1 | 3.890088 | 50 | 50.0 | 6.684 |
For SI: 1 gallon per minute = 3.785 L/m, 1 cubic foot per minute = 0.4719 L/s.
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