What is a Bag Filter

Bag Filter March 21, 2025 Single Bag Filter Housing

Filtration Mechanism of Bag Filter:
When liquid flows through the filter bag, solid particles are trapped either on the surface or inside the filter bag, while the clean liquid exits through the outlet.

Filtration Types:
- Surface Filtration: Particles are retained on the surface of the filter bag.
- Depth Filtration: Particles penetrate and are retained inside the filter bag.

Working Process:

The liquid enters the filter through the inlet.
It passes through the filter bag and exits through the outlet as filtered liquid.
As filtration progresses, a filter cake forms on the surface of the filter bag, increasing the differential pressure. When the pressure difference becomes significant, the filter bag must be replaced or cleaned.

Structure and Components of a Bag Filter:

Main Components:

Filter Bag: The core filtration element. The material and filtration precision determine the filter’s performance.
Filter Basket: Provides structural support to the filter bag, preventing collapse. It is typically made of stainless steel.
Housing (Filter Body): Contains the filter bag and filter basket, with material options such as carbon steel, stainless steel, or plastic.
Cover: Seals the filter body to ensure leak-proof operation. It is often equipped with a quick-opening mechanism.
Inlet and Outlet Ports: Connect to pipelines and are designed to meet flow rate and pressure requirements.

Auxiliary Components:

Differential Pressure Gauge: Monitors the clogging status of the filter bag and indicates when it needs replacement.
Air Vent Valve: Removes air from the system to prevent airlocks.
Drain Outlet: Used for cleaning or draining the filter.