Air Conditioning Air Handling Units (AHUs) and purified fresh air systems are widely employed in high-standard environments such as commercial buildings, hospitals, laboratories, and cleanrooms. Their primary requirements include long-term airtightness without leakage, contamination-free clean air, maintenance-free durability, and compliance with fire safety standards. These systems demand more than basic sealing from foam silicone materials; they impose stringent requirements for structural stability, environmental performance, weather resistance, and safety parameters-a key distinction between premium vapor-phase foam silicone and conventional solid-phase foam silicone in practical applications.
1. Ultra-low permanent deformation under compression, ensuring long-term airtight stability
The maintenance doors and filter cover plates of AHU units remain in a tightly closed state for extended periods, with the equipment operating continuously year-round, causing continuous compression on the sealing gaskets. This demands that the foam silicone exhibit ultra-low permanent compression deformation (≤8%), allowing rapid rebound under pressure without collapse or relaxation. It prevents elastic degradation and crack formation in conventional foam under prolonged pressure, eliminates issues such as system pressure loss, increased energy consumption, and failure to meet cleanliness standards, thereby meeting the requirement for long-term sealing (5–8 years) without frequent replacement.
II. Fine, uniform closed-cell structure for high-precision airtight dust prevention
The purification fresh air system imposes extremely stringent requirements on duct airtightness and dust/humidity resistance, necessitating complete prevention of external dust, moisture, and unfiltered air from entering the unit interior. The appropriate foam silicone must possess a dense, uniform closed-cell structure free from large pores or porous defects; when fitted into irregular gaps of the metal housing, it ensures full sealing, effectively blocking airflow penetration, dust ingress, and condensation vapor infiltration, thereby preventing internal dust accumulation, mold growth, and bacterial proliferation while maintaining stable compliance with clean air delivery standards.
III. Low odor, low volatility, and excellent environmental-friendly cleaning performance
Medical, laboratory, and cleanroom environments demand zero tolerance for air quality; sealing materials must not release harmful substances or odors. Foamed silicone used in AHUs and purification systems must meet sulfur-free, low-VOC, odor-free, and non-exfiltration requirements, with certifications such as SGS and REACH compliance. It prevents the volatilization of hazardous gases or emission of pungent odors under high-temperature conditions, eliminates secondary indoor air pollution, and fully meets the air quality standards required for enclosed clean spaces.
IV. Broad Temperature Range, Weather Resistance, and Resistance to Thermal Aging
AHU units operate under continuous conditions of alternating thermal cycles and constant air supply, experiencing frequent temperature fluctuations. Conventional sealing materials are prone to hardening, shrinkage, cracking, and degradation over time. Specialized foam silicone must withstand a wide temperature range of-60°C to 230°C stably, without hardening, shrinking, or deforming under prolonged thermal cycling and humid environments; it exhibits resistance to ultraviolet radiation and moisture-induced aging, meets stringent requirements for year-round uninterrupted operation, and complies with long-term performance standards for commercial and industrial HVAC systems.
V. UL94 V0 Class Flame Retardant Safety Performance
HVAC purification systems constitute core mechanical and electrical facilities in buildings and must comply with fire safety regulations. The selected materials must meet the UL94 V0 high flame retardancy rating, exhibiting self-extinguishing properties upon removal from flame, non-combustibility, no dripping, minimal smoke emission, and non-toxicity. These materials effectively prevent the spread of smoke and flames through duct gaps, fulfilling the fire safety acceptance standards for hospitals, public buildings, and cleanrooms, representing mandatory safety requirements for premium HVAC purification systems.
VI. High flexibility and tear resistance, suitable for frequent opening/closing operations
AHU filters and inspection doors require regular opening and closing for maintenance, with filter screens needing replacement. Sealing gaskets must undergo repeated stretching, bending, and compression tests. The foam silicone used must exhibit excellent flexibility, tear resistance, no whitening or chip loss under tension, tolerance to long-term mechanical wear from opening/closing cycles, resistance to damage or powder discharge, prevention of debris entering air ducts to contaminate fresh air, and preservation of structural integrity over extended use.
VII. Shock Absorption, Noise Reduction, and Structural Compatibility
The operation of the unit's fan generates continuous vibrations, which can easily induce resonance noise in the metal casing. Qualified foam silicone exhibits excellent cushioning and shock-absorbing properties, effectively absorbing operational vibrations, reducing resonance-induced noises, and enhancing the quiet performance of the HVAC system. Additionally, its high plasticity enables die-cutting and custom back-coating, making it perfectly suited for irregular sealing installations on various unit door panels, filter frames, and housing flanges.