Sump / Ejector Basin Drawdown and Cycle Check
Drawdown volume, run and fill times, cycles per hour, and a short-cycle verdict for a sump or sewage-ejector basin against its inflow and pump rate.
Formula and source
area_ft2 = (PI/4)(basin_dia/12)^2; drawdown_gal = area_ft2 x (drawdown_in/12) x 7.48; run_time_s = drawdown_gal / (pump_gpm - inflow_gpm) x 60; fill_time_s = drawdown_gal / inflow_gpm x 60; cycles_per_hr = 3600 / (run + fill); adequate = run_time_s >= min_run_s.
IPC 2021 Section 712 (Sumps and Ejectors) and the Hydraulic Institute pump-cycling guidance by name; first-principles basin geometry and cycle math.
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