Coalescence filters with fiberglass cartridges
for heavy-duty processes

Candle filters are an advanced solution for the separation and purification of gas streams containing oil mists, submicron liquid particles, contaminated fumes, or industrial aerosols. Their structure consists of cylindrical filtering elements—commonly referred to as candles—made from high-efficiency fibrous materials such as fiberglass, arranged to maximize the filtering surface.

This technology leverages the principle of coalescence, which is the ability to aggregate microdroplets dispersed in a gas stream into larger, more easily separable particles. These droplets are captured by the filter fibers and coalesce into larger drops that can then be drained by gravity into a collector, enabling effective purification even of submicron mists.

Thanks to their high filtration efficiency (up to 99.99% for particles smaller than 1 micron) and robust construction, candle filters are particularly suitable for heavy-duty, continuous applications typical of the metallurgical, chemical, bitumen, food processing, and heat treatment industries. They are also used as intermediate stages in multi-stage purification plants, in combination with dry filters, scrubbers, or odor and VOC abatement systems.

This versatility, combined with ease of maintenance and the long service life of the filter cartridges, makes candle filters an extremely reliable solution for ensuring air quality in the most demanding production processes.

Operating Principle

Candle filters operate based on the coalescence phenomenon. The contaminated gas stream passes through the filter cartridges: liquid particles (such as oil mist) or solids are trapped within the filter fibers, where they aggregate into larger droplets that are then drained by gravity.

The cartridges are generally composed of multiple layers:

• Prefiltration layer (e.g., cellulose or metal mesh),
• Coalescing section (fiberglass),
• External protective support (e.g., polyester).

Submicron separation is made possible by the Brownian motion of the smallest particles, which are effectively captured even below 1 micron. Typical efficiency ranges from 99% to 99.98% for particles as small as 0.1 microns.

Technical Specifications

• Air/gas flow rate: from 750 m³/h to higher values
• Number of cartridges: from 1 to multiple units, Ø600 mm – H 1,200 mm.
• Filter material: fiberglass, multilayer with external polyester support.
• Filtration efficiency:
  • 100% for particles ≥ 3 microns,
  • 99.98% for particles
  • 99.9% for particles ≥ 0.3 microns.

Accessories / Optional Components

• Remote monitoring of operating data via HF monitoring platform.
• Option to install systems for recovery of oil/fluids collected in the hopper.