Automatic Backwash Filters and Strainers

Introduction

Lefilter® Automatic Backwash Filters and Strainers are engineered based on advanced scanning self-cleaning filtration technology. When standard internal backwashing is insufficient to fully regenerate the filter screen, the system employs an enhanced high-pressure (H.P.) injection backwash mechanism, ensuring thorough cleaning even under demanding conditions—such as high total suspended solids (TSS), ultra-fine filtration down to 5 microns, viscous contaminants, or low inlet pressure.

These filters effectively eliminate suspended solids, sediments, and plankton from water or similar liquids while maintaining uninterrupted operation. The self-cleaning process is highly efficient, allowing continuous filtration without downtime during backwashing. Additionally, Lefilter® offers chemical-grade designs to handle extreme conditions, including high temperature, high pressure, explosion-proof requirements, and zero leakage.

With robust performance and adaptability, Lefilter® Automatic Backwash Filters deliver reliable solutions for the most challenging industrial filtration needs.

Working Principle

The fluid enters the filter through the inlet, passes through the mesh screen, and exits via the outlet, while contaminants are trapped on the screen surface. As particles accumulate, the pressure drop across the filter increases until it reaches a predetermined threshold (typically 50 kPa). At this point, the control system initiates the cleaning cycle.

The backwash valve opens, activating the high-pressure pump (operating at 1.5–2.0 MPa). A geared motor drives the cleaning shaft in a combined helical and reciprocating motion. The shaft is equipped with internal suction nozzles and external high-pressure (H.P.) jets, both aligned to target the same section of the screen. As the shaft rotates, the nozzles traverse the screen, removing debris. When the backwash valve opens, a pressure differential forms at the nozzle contact point (ΔP = outlet pressure – backwash outlet pressure), causing filtered liquid to reverse-flow through the screen into the suction nozzles. Simultaneously, the H.P. pump recirculates clean liquid to enhance the backflush efficiency. The high-velocity reverse flow dislodges trapped particles, restoring the screen’s filtration efficiency. Once the entire screen is cleaned, the cycle completes. The filtration process continues uninterrupted during backwashing, with minimal flow or pressure fluctuations.

The Lefilter system supports two operating modes:

1.Continuous Suction + Injection Backwash: Each cleaning cycle combines suction and high-pressure jet cleaning.

2.Adaptive Suction + Injection Backwash: The H.P. jets activate only when the suction backwash interval falls below a set limit, optimizing energy use.

Specification

Q&A

1. What is a backwash filter?

A backwash filter is a type of filtration system that cleans itself by reversing the flow of water to flush out trapped contaminants. This process dislodges debris from the filter media, allowing it to be drained away, ensuring continuous filtration efficiency without frequent manual cleaning.

2. How does a backwash filter work?

During normal operation, water flows through the filter media (such as sand or activated carbon), trapping impurities. When backwashing is initiated, the flow is reversed, expanding the media and lifting trapped particles. The dirty water is then discharged, leaving the filter clean and ready for reuse.

3. What are the advantages of using a backwash filter?

• Reduced maintenance: Automatic backwashing minimizes manual cleaning.

• Continuous operation: The system can often keep filtering while backwashing.

• Longer filter life: Regular backwashing prevents clogging and media degradation.

• Cost-effective: Less downtime and lower replacement costs compared to disposable filters.