Introduction to Baghouse / Fabric Filters: Design Criteria

Ideal air-to-cloth ratios for fabric filters:

• Reverse Gas 1.75:1 “ 2.50:1
• Pulse Jet 3.25:1 “ 4.00:1
• Shaker 2.0:1 “ 2.50:1

P/J System Recommendations

• High and hi-hi hopper level indicators
• Vacuum breaks for top access door
• Inlet injection ports for pre-coat and leak dye
• Lay-down area for bags and cage storage
• Redundant compressed air systems
• Quality compressed air dryers

P/J Can Velocity

• Air volume
• Compartment area (LxW = ft², measured at bottom of bags
• Bag area (# of bags x area of bag bottom = ft²)
• Open area (collector area “ bag bottom area)
• Can velocity = (air volume ÷ open area)
• Typical P/J can velocity: 200-400 feet per min

R/A System Recommendations

• Quality isolation dampers and actuators (poppet type)
• High and hi-hi hopper level indicators
• Vacuum breaks for top access door
• Inlet injection ports for pre-coat and leak dye
• Lay-down area for bags and cage storage
• Redundant reverse air fans
• Reverse air recirculation system
• Piping for acoustic horns even if not initially installed

Instrumentation Functions

• Differential pressure for entire baghouse and individual compartments
• Inlet and outlet temperature (dew points)
• Emission monitoring for individual compartments (broken bag detectors)
• Reverse gas temperature and pressure
• Compressed air PSI, temp, and flow rate
• Damper positions
• Acoustic horn sounding time and PSI
• High and hi-hi hopper level indicators
• Filter bag permeability tester

Helpful Resources

KnowledgeBase: Baghouse Design Factors

KnowledgeBase: Common Baghouse Misconceptions

KnowledgeBase: Types of Fabric Filters

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