Design & Sizing第 26 / 110 题
A sewage sump receiving a peak inflow of 45 gpm is served by a pump that discharges 90 gpm when running. If useful storage between pump-on and pump-off is 30 gallons, how long does one pump-down cycle (running time) last during peak inflow?
a.30 s
b.40 s
c.60 s
d.90 s
解析
While running, the net removal rate is pump output minus inflow = 90 - 45 = 45 gpm. Draw-down time = storage / net rate = 30 / 45 = 0.667 min = 40 s. Sizing sump volume this way limits motor starts per hour to protect the pump; too small a volume causes short-cycling.
法律依据: IPC §712.4免费刷完整 110 道题库 — 无需注册。
同考点相关题目
- A recirculation loop must deliver 6 gpm of hot water. Using v = 0.408 x Q / d^2, what inside diameter keeps the velocity at about 2 ft/s to limit erosion of the continuously circulated hot line?
- A water main runs 250 ft of developed length and the friction chart shows a loss of 6 psi per 100 ft at the design flow. How much pressure is lost to friction over the full run?
- A sewage ejector pump must handle a building with a discharge of 30 gpm against 18 ft of total head. Using WHP = (gpm x head in ft) / 3,960, what is the water horsepower?
- Two demand loads combine on a main: branch A carries 40 WSFU and branch B carries 60 WSFU. If the Hunter demand chart converts 100 WSFU (predominantly flush tanks) to about 44 gpm, what design flow sizes the main?
- A meter and service must supply 44 gpm. The static supply is 68 psi, elevation loss is 20 psi, the meter loss is 8 psi, and the most remote fixture needs 15 psi. How much pressure remains for pipe friction?
- An individual vent serving a lavatory is 1-1/2 in. The vent sizing table limits a 1-1/2 in vent to a maximum developed length of 150 ft at the fixture-unit load carried. If the vent run is 90 ft, is the vent acceptable and why?