HK1170975A - Stormwater filtration apparatus, system and method - Google Patents

Abstract

A stormwater filter cartridge includes a housing having a water inlet and a filtered water outlet, and a filter medium disposed along a flow path between the water inlet and the filtered water outlet. A drainage space forms at least part of the flow path and is disposed between a downstream side of the filter medium and the filtered water outlet. A solid wall float tube disposed in the drainage space has an open lower end and open upper end, the solid wall float tube movable between a lowered position that inhibits or substantially restricts filtered water at the bottom of the drainage space from passing to the filtered water outlet and a raised position that permits free flow of filtered water to the filtered water outlet. A fluid reservoir is in fluid communication with the drainage space and is disposed within the housing and above the filter medium for collecting filtered water as water level in the housing rises while the solid wall float tube is in the lowered position. As the housing fills, water level in the housing rises to cause the solid wall float tube to move to the raised position and a negative pressure can be established in the housing that draws fluid through the filter medium. As water level outside the filter cartridge drops, air enters the housing via the water inlet and causes the solid wall float tube to drop to the lowered position, and filtered water in the fluid reservoir backflows through the filter medium and out of the housing through the water inlet while air enters the housing by passing upward through the solid wall float tube so as to enhance rate of backflow.