The automatic self-cleaning filter uses a straining element to directly remove suspended solids from water, protecting downstream equipment. Water enters the housing, while an intelligent control system (PLC/PAC) continuously monitors pressure differential. When clogging reaches a preset level, the system automatically signals the drain valve to initiate backwashing—without interrupting the main flow. This design overcomes traditional filter drawbacks such as small dirt-holding capacity, frequent disassembly for cleaning, and lack of status monitoring. It provides reliable filtration, automatic contaminant flushing, real-time operational visibility, and a high degree of automation.
Operating Principle (4-Stage Cycle)
Normal Filtration – Water enters through the inlet and passes through the filter media from inside to outside. Contaminants such as sand, rust, and suspended solids are trapped on the inner surface of the media, while clean water exits through the outlet.
Trigger – As debris accumulates, the pressure differential across the filter rises. When it reaches the set point (typically 0.05–0.1 MPa) or a preset time interval is reached, the PLC initiates the backwash cycle.
Backwash – The drain valve opens and flow reverses direction, moving from outside to inside. The media is flushed at 3–5 times the normal flow velocity. The high-speed scouring strips away trapped contaminants and discharges them through the drain port. The process is typically carried out element-by-element or group-by-group, without interrupting the main flow.
Restoration – After 10–60 seconds, the drain valve closes. The pressure differential returns to normal, and the filter resumes its normal filtration state.
Core Components
Housing – Made of carbon steel or stainless steel, with a pressure rating of 1.0–1.6 MPa.
Filter Media / Elements – Available in stainless steel wedge wire, woven mesh, disc stacks, or sintered elements, with filtration precision ranging from 10 to 3000 μm.
Backwash Mechanism – Driven by electric motor or hydraulically, using suction scanners, rotating nozzles, or multi-valve switching arrays.
Control System – PLC-based, equipped with differential pressure sensors and/or timers, supporting both automatic and manual operation modes.
Drain Valve – Electrically or pneumatically actuated quick-opening valve for discharge control.
Main Types
By Media / Structure:
Wedge Wire / Woven Mesh Filters – The most common type, with filtration precision of 50–500 μm. Suitable for coarse particles and high-turbidity water.
Disc Filters – Composed of stacked plastic discs under compression. Feature good self-cleaning capability and are widely used in agriculture and municipal water treatment.
Sand / Activated Carbon Filters – Deep-bed filtration type; backwashing restores the media bed. Used for raw water and wastewater pretreatment.
Multi-Cartridge Filters – Consist of 3 to 9 cartridges arranged in parallel, with individual cartridge backwashing. Offer high flow capacity and higher precision (5–100 μm).
By Control Mode:
Differential Pressure Control – The most common mode. Backwash is initiated only when blockage occurs, making it energy efficient and ideal for variable operating conditions.
Timed Control – Operates on a fixed schedule (e.g., every 24 hours). Simple and reliable, best suited for stable water quality conditions.
Manual Control – Used in small or household pre-filters. Requires manual valve operation to initiate flushing.
Features:
