方法
根据输入的滤料和水性质计算正常及少一格滤池工况的负荷、反冲洗流量/水量和清洁床分层 Ergun 水头损失。颗粒直径应输入体积等效球形直径，并单独应用球形度；Ergun 结果仅为清洁床筛选值。
Normal rate = plant design flow / total active filter area. One-filter-out rate uses (N−1) equal filter areas. Rates are reported in m/d and m/h.
Backwash flow = backwash rate × area per filter. Wash volume = flow × duration. Daily volume includes entered washes per filter per day.
Backwash-water fraction = gross daily backwash-water volume / entered plant design flow; it does not represent net recovery.
Clean-bed headloss uses the Ergun equation for each entered layer and sums the layer losses. Enter the volume-equivalent spherical particle diameter; sphericity is applied separately. Velocity converts m/h to m/s; pressure drop converts to head using entered density and standard gravitational acceleration.
A declared bed expansion is applied to layer depth for a geometric screen only. Leaving it blank omits that screen.