To evaluate a high-efficiency filter, consider multiple dimensions and performance indicators.
I. Core Performance Indicators
1. Filtration Efficiency
- Measures the filter's ability to capture particles. Key metrics include:
1.1 MPPS Efficiency: The efficiency at the Most Penetrating Particle Size (MPPS), typically 0.1–0.3 micrometers. A high MPPS efficiency ensures reliable performance.
1.2 Fractional Efficiency : Efficiency across various particle sizes (e.g., 0.3μm, 0.5μm, 1.0μm, 5.0μm) for a comprehensive profile.
1.3 Relevant Standards: HEPA (EN 1822-1: H13≥99.95%, H14≥99.995%), ULPA (U15≥99.9995%, U16≥99.99995%, U17≥99.999995%).
2. Resistance or Pressure Drop
- The energy loss as air flows through the filter, measured in Pascals (Pa). Lower initial resistance means greater energy savings and potentially longer filter life.
3. Dust Holding Capacity
- The total amount of dust the filter can hold before reaching terminal resistance, measured in grams (g). Higher capacity means longer life and lower maintenance costs.
II. Filter Media Technology
1. Filter Media Types
1.1 Glass Fibers: Traditional, efficient, heat-resistant, but high resistance and brittle.
1.2 PP/PET Melt-Blown Fibers: Modern, lower resistance, flexible.
1.3 Composite Media: e.g., ePTFE membranes for surface filtration, high efficiency, easy cleaning.
2. Electret Technology
- Enhances efficiency with static charge, but charge can decay over time, reducing effectiveness.
3. Fiber Structure and Gradient
- Gradient density filters capture larger particles on the intake side and finer particles on the exhaust side, balancing efficiency and capacity.
III. Structural Design
1. Pleating Design
1.1 Pleat Height: Higher pleats increase filtration area.
1.2 Pleat Count and Spacing: Balance area and resistance.
1.3 Separator: Prevents pleats from collapsing, options include aluminum foil (strong, precise) and hot melt adhesive (lightweight, cost-effective).
2. Sealing Integrity
- Ensures all air passes through the media, measured by scan tests for leaks.
3. Frame Material
- Options include wood (not recommended), laminated board, aluminum/steel (high strength), and plastic (lightweight).
IV. Comprehensive Performance and Test Verification
1. Energy Efficiency Factor
- Measures high efficiency with low resistance: -log(Penetration Rate) / Pressure Drop.
2. Authoritative Certification
- Third-party reports based on standards like EN 1822, IEST-RP, GB/T 13554, verifying MPPS efficiency, initial resistance, and dust holding capacity.
In summary, selecting a high-efficiency filter requires a balanced assessment of efficiency, resistance, and capacity, along with detailed evaluations of media technology, structural design, and authoritative test results.
