Méthodologie
Calcule les charges normale et avec un filtre indisponible, le débit/volume de lavage et la perte de charge Ergun d’un lit propre multicouche à partir des propriétés saisies. Saisir le diamètre sphérique équivalent en volume et appliquer séparément la sphéricité; Ergun reste une estimation de lit propre.
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.