Backflush valves (also known as Backwash valves) are 3-way hydraulically operated diaphragm valves commonly used in filtration applications with media and disc filters. The valve has a common outlet connected to the filter inlet and two other outlets, one connected to the water inlet manifold, the other to the drain manifold. The valve can be set in one of two positions:
- Filtration mode allows flow from the inlet manifold into the filter.
- Flushing mode closes the filter connection to the inlet manifold and connects the filter inlet to the drain outlet resulting in reversal flow of filtered water from neighbouring filters through the filter.
A Backflush valve can be operated automatically using a solenoid valve or manually using a 3-way selector valve.