Bag-House Filter Bag Set

Function

Filter bags are the regulatory compliance component of the plant — they determine whether stack particulate emissions remain within permitted limits, typically 50–100 mg/Nm³ depending on the country of operation. Beyond compliance, effective bag filtration recovers fine mineral filler that is a formulation component of the asphalt mix, reducing material waste. As bags blind or develop pin-holes through temperature excursions, chemical attack or mechanical abrasion at the snap-ring collar, filtration efficiency drops — raising stack opacity, attracting regulatory penalties and reducing filler content in the mix. Planned bag replacement on a scheduled basis (typically every 12–18 months of continuous operation) is more cost-effective than reactive replacement after a stack violation.

Construction & quality

Fabric: PPS (polyphenylene sulphide / Ryton) needle felt or polyimide (P84) felt for continuous operating temperatures of 160–200 °C (320–392 °F) and peak excursions to 230 °C (446 °F). PTFE membrane finish on the clean gas side for enhanced particle release during pulse cleaning and reduced pressure-drop blinding. Needled felt weight: 500–700 g/m². Seams are ultrasonically welded or thermally bonded — not stitched — to prevent particle bypass at seam lines. Each bag is individually length-trimmed to the customer's tube sheet collar depth and supplied with a galvanised or stainless-steel snap ring for positive tube-sheet seating.

When to replace

• Elevated stack opacity or particulate emission alarms — the most rapid field indicator of bag failure.
• Visible pin-holes, tears or surface erosion on bag exterior during internal baghouse inspection at shutdown.
• Abnormally high baghouse differential pressure indicating bags are blinded and the pulse cycle is failing to clean them.
• Abnormally low differential pressure suggesting bags have failed open — no longer creating filtration resistance.
• Blue or grey plume visible at the stack during normal production conditions.