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G3 vs G4 Primary Air Filters: Efficiency Standards and Selection Best Practices

 

Why Filter Efficiency Matters
In commercial HVAC systems, primary filters serve as the first line of defense, capturing 85%+ of airborne particulates above 5μm. Our ISO 16890-certified testing demonstrates how G3/G4 filter selection impacts operational efficiency and maintenance costs.


1. Understanding Efficiency Classifications

1.1 ASHRAE vs. ISO Testing Methods

  • ASHRAE 52.2 MERV: G3 ≈ MERV 6 | G4 ≈ MERV 8 (PM1-PM10 scale)
  • ISO 16890 Reporting: G3 = ePM10 50% | G4 = ePM10 70%
    Note: Dual labeling (MERV + ISO) is recommended for North American markets

1.2 Key Performance Metrics

Parameter G3 Filter G4 Filter
Arrestance (ASHRAE) 65-80% 80-90%
Initial Pressure Drop ≤0.28 in.w.g. (70Pa) ≤0.32 in.w.g. (80Pa)
Dust Holding Capacity 14-18 oz/yd² 18-22 oz/yd²

2. Application-Specific Recommendations

Ideal G3 Applications:
✔️ Retail store rooftop units (RTUs)
✔️ Warehouse ventilation pre-filtration
✔️ School HVAC systems (ANSI/ASHRAE 62.1 compliant)

When to Choose G4:
✔️ Hospital patient rooms (FGI Guidelines compliance)
✔️ Data center AHUs (ASHRAE TC9.9 compatible)
✔️ Manufacturing facilities requiring OSHA PEL compliance


3. Engineering Innovations

Our American-market optimized filters feature:

  • Dual-Stage Filtration: Outer synthetic fiber layer (100% PP) for large particulates + inner electrostatic media for fine particle capture
  • Corrosion-Resistant Frames: 20GA galvanized steel meeting ASTM A653 SS Grade 33 specifications

4. Total Cost of Ownership Analysis (NREL Model)**

5-year ROI when upgrading from G3 to G4:

Facility Type Energy Savings Filter Replacement Savings Labor Reduction
Office Buildings 12% $380/year 22 hours
Research Labs 18% $620/year 35 hours