How Self Cleaning Strainers Work

Self-cleaning strainers, also known as automatic backwashing strainers or self-cleaning filters, work on a simple yet effective principle. They use an automatic cleaning mechanism to remove accumulated debris from the filter element, ensuring uninterrupted flow and maintaining the strainer's efficiency. Let's take a closer look at how self-cleaning strainers work:

1. Filtration Stage:

During normal operation, the fluid (liquid or gas) enters the strainer housing through an inlet and flows through the filter element. The filter element is typically made of a fine mesh or has perforations, which are designed to trap and retain solid particles present in the fluid.

2. Accumulation of Debris:

As the fluid passes through the strainer, solid particles in the fluid are trapped by the filter element, and over time, they accumulate on its surface. This accumulation leads to an increased pressure drop across the strainer as the flow encounters resistance from the clogged filter.

3. Automatic Cleaning Cycle Initiation:

To prevent excessive pressure drop and maintain the strainer's effectiveness, a self-cleaning strainer is equipped with an automatic cleaning mechanism. This mechanism is activated when certain conditions are met, such as:

A preset pressure differential across the strainer is reached.

A predetermined time interval has passed since the last cleaning cycle.

Other sensors or indicators detect the need for cleaning based on the specific design and requirements of the strainer.

4. Backwashing Process:

When the automatic cleaning cycle is initiated, the self-cleaning strainer performs a backwashing process to remove the accumulated debris from the filter element. The backwashing process typically involves the following steps:

Flow Reversal: In some self-cleaning strainers, the flow direction is temporarily reversed. The fluid is directed back through the filter element in the opposite direction from the normal flow. This reversal causes the accumulated debris to dislodge from the filter surface.

Cleaning Mechanism Activation: In other self-cleaning strainers, a separate cleaning mechanism, such as rotating brushes or jets of fluid, is activated. These cleaning mechanisms physically remove the debris from the filter element.

5. Disposal of Debris:

Once the debris is dislodged from the filter element, it is flushed out of the strainer housing and directed to a waste outlet. The waste outlet is designed to ensure that the removed debris does not re-enter the main fluid stream but is instead collected and disposed of separately.

6. Resuming Filtration:

After the backwashing process is complete and the accumulated debris is removed, the self-cleaning strainer returns to its normal filtration mode. The clean filter element is ready to trap and retain new solid particles from the fluid stream.

Unlike conventional static strainers or filters that require manual cleaning or replacement when they become clogged, a self-cleaning strainer automatically cleans itself at regular intervals or when the pressure drop across the strainer exceeds a certain threshold. This automated cleaning process helps maintain the strainer's efficiency and ensures uninterrupted flow in the system.

Click here to learn about: The Ultimate Automatic Self-Cleaning Filter Guide: Enhancing Filtration Efficiency