Key Differences: Primary vs. High-Efficiency Filters
Primary filters (e.g., G4) and high-efficiency filters (e.g., HEPA/ULPA) are core to graded air purification, with distinct roles. Below are their key differences:
1. Filtration Efficiency & Targets
Primary (G4): Follows EN779/GB/T 14295; 80%-90% efficiency for ≥5μm particles (hair, lint, visible dust); role: "coarse filtration" to reduce downstream load.
High-Efficiency (HEPA H13/ULPA): Follows EN1822/GB/T 6165; HEPA H13: ≥99.97% for 0.3μm particles (PM2.5, viruses); ULPA U15: ≥99.995% for 0.12μm particles; role: "fine filtration" to meet cleanliness standards.
2. Media & Structure
Primary: Non-woven/coarse glass fiber, simple pleated design, aluminum/galvanized steel frame (low-cost, easy replacement).
High-Efficiency: Ultra-fine glass fiber/PTFE coating, seamless/seamed structure with sealing strips (anti-bypass), stainless steel/high-strength plastic frame (durable, precise).
3. System Position
Primary: Front-end ("first line of defense"); protects downstream filters/equipment (extends HEPA life by 70%-80%); no direct cleanliness responsibility.
High-Efficiency: Terminal ("last line of defense"); ensures air quality (e.g., ≤3.5 particles/L for 0.5μm in hospitals); directly determines final cleanliness.
4. Applications
Primary: HVAC pre-filtration (buildings), industrial equipment intake (air compressors), harsh environment protection (desert base stations).
High-Efficiency: Cleanrooms (electronics/pharmaceuticals), medical settings (ORs/ventilators), high-end air purifiers, food aseptic workshops.
5. Resistance & Energy
Primary: Low initial resistance (≤50Pa), final ≤200Pa; low fan pressure demand, minimal energy use.
High-Efficiency: Higher initial resistance (150-200Pa for HEPA H13), final ≤500Pa; needs high-pressure fans, 5%-10% of HVAC energy consumption.
6. Replacement & Cost
Primary: Low-cost (tens to hundreds of yuan/unit); short cycle (3-6 months, 1-2 in harsh environments); "high-frequency, low-cost".
High-Efficiency: High-cost (thousands to tens of thousands yuan/unit); long cycle (1-3 years, up to 5 in cleanrooms); "low-frequency, high-cost" (relies on primary protection).
Conclusion
They are synergistic, not substitutable: Primary filters (low-cost guardians) enable efficient, low-energy systems; high-efficiency filters (precision terminators) meet strict cleanliness. Mature systems use "primary→medium→high-efficiency" for balanced performance and cost.
