Tank capacity Underground tank capacity = No of persons * water demand per person * no of storage days Underground tank capacity = 300 * 28 *2 = 16800 gallons = 65 m3 Pump calculations Each floor has 3 lavatories, 3 urinal and 9 WC. WC (flush valve) = 10 WFUS Urinal (flush valve) = 5 WFUS Lavatory = 1.5 WFUS WFUS in each floor = 3*1.5 + 3*5 + 9*10 = 109.5 WFUS All WFUS in the building = 219 WFUS 219WFUS = 70 GPM Q pump = 70 GPM = 4.4 L/sec P pump = Static pressure + Friction loss + Residual pressure Static head = 10 m Friction loss = (6* (3.2/100) + 4* (3.9/100) + 73* (14.1/100)) * 1.3 Friction loss = 14 m Residual pressure for the flush valve WC (The most distant device) = 1.7 bar = 17.5 m P pump = 10 + 14 + 17.5 = 41.5 m = 42 m Water heater calculations One water heater for every bathroom group (3 Lavatories) So, we need 4 Water heaters for the project Water heater capacity = GPH * Demand factor * Storage factor Water heater capacity = 15 * 0.4 * 1 = 6 Gallon = 25 Liter Q Water heater = Mo * Cp* (Th-Tc) Cp = 4.186 KJ/ kg.k Th-Tc = 55 oC Q Water heater = 1.5 KW
