What is an Automatic Backwash Filter

JX Filtration November 29, 2024 Backwash Filter

An automatic backwash filter operates through two main processes: filtration and automatic backwashing. The working principle involves the following steps:

Filtration Process

Liquid Inflow
Liquid containing suspended particles enters the filter through the inlet.
Impurity Capture
As filtration continues, impurities in the liquid are captured on the surface of the filter element (e.g., filter screen). This leads to an increase in pressure and filtration resistance, reducing filtration efficiency.
Pressure Differential Control
When impurities accumulate to a certain level, the pressure differential across the filter element reaches a preset value. At this point, a pressure differential controller sends a signal to the control system.

Automatic Backwash Process

Signal Transmission
Once the pressure differential reaches the preset threshold, the pressure differential controller signals the control system.
Backwash Activation
The control system triggers the motor and electric valve to start the automatic backwash process.
Waste Discharge Operation
- The drain valve opens, releasing pressure and discharging water.
- A significant pressure drop creates a vacuum effect in the hydraulic motor chamber and suction pipe, allowing suction nozzles to remove debris from the inner surface of the fine filter screen. The debris is carried into the hydraulic motor chamber and finally expelled through the drain valve.
- As water flows through the hydraulic motor, it rotates the suction pipe. Simultaneously, the hydraulic cylinder piston moves the suction pipe axially. This combined rotational and axial movement cleans the entire inner surface of the filter screen.
End of Backwash
The drain valve closes at the end of the cleaning cycle, and the increased water pressure causes the hydraulic cylinder piston to return to its initial position. At this point, the filter is ready for the next backwash cycle.
System Reset
After the backwash process is complete, the system resets to its initial state, ready for the next filtration operation.