High-efficiency filters face the challenges of extreme environments, and the seal between the housing and frame is the “last line of defense.” Specialized seals, based on temperature, humidity, chemical media, and durability requirements, create an indestructible physical interface for the “cleanliness barrier.”
Liquid Silicone Rubber Injection Molding Seals
Liquid silicone rubber injection molding technology is a process in which two-component liquid silicone rubber is injected under high pressure and rapidly vulcanized in a precision mold. It is becoming the preferred seal for high-end filters, especially in fields with stringent cleanliness and reliability requirements.
Core Technology Advantages:
- Superior sealing performance and consistency: The liquid silicone flows and fills within the mold, perfectly conforming to the complex grooves of the filter frame, achieving seamless, overflow-free molding and eliminating leakage points at the source.
- Wide Temperature Range: High-quality addition-cured liquid silicone rubber maintains its elasticity and sealing performance over a wide temperature range of -60℃ to 250℃, easily withstanding the thermal shock during equipment start-up and shutdown.
- Exceptional Chemical Stability and Purity: Silicone itself possesses excellent weather resistance and chemical inertness. More importantly, its vulcanization process is an addition reaction, producing almost no byproducts or small molecule volatiles , preventing the seal itself from becoming a source of contamination. This is crucial for industries such as semiconductors and biopharmaceuticals, which are extremely sensitive to VOCs (volatile organic compounds).
This technology is an ideal choice for high-efficiency filters in biopharmaceutical sterile workshops, hospital laminar flow operating rooms, high-end laboratories, and precision electronic assembly lines. It ensures reliable sealing even under long-term temperature fluctuations and routine disinfectant wiping. However, its resistance to continuous erosion by strong acids ,strong alkalis , or certain special solvents has a clear upper limit.
Special Polyurethane Cold Sealing:
Unlike traditional seals that require heat curing, polyurethane cold sealing adhesives (especially single-component products) can cure at room temperature by absorbing trace amounts of moisture from the air. This characteristic gives it irreplaceable value in specific scenarios.
Core Technical Advantages:
- Excellent Construction Adaptability and Adhesion Broadness: It requires no mixing or heating equipment, is easy to apply, and can be used in ambient temperatures ranging from -45℃ to 90℃. It exhibits strong adhesion to various filter frame materials, including metals, plastics, and glass.
- Superior Elasticity and Fatigue Resistance:After curing, it forms a highly elastic rubber body with an elongation at break exceeding 300%. This allows it to effectively absorb and compensate for dynamic stresses caused by equipment vibration, wind pressure fluctuations, or minor deformations, preventing seal cracking due to fatigue.
- Good Weather Resistance and Media Resistance: It possesses resistance to UV rays, ozone, weak acids and alkalis, and greases, resulting in a long service life.
It is ideal for on-site sealing and maintenance of filters in HVAC systems, general industrial cleanrooms, and large outdoor or vibrating air handling units. For non-extreme chemical environments but with temperature and humidity variations and mechanical vibrations, it provides a durable and reliable dynamic seal. However, its performance will significantly degrade in long-term high-temperature environments exceeding 90℃ or in strong oxidizing environments.
Metal-Ceramic High-Temperature Sealing
When ambient temperatures exceed the limits of conventional materials, or when facing extreme conditions such as strong corrosion, high vacuum, or strong radiation, metal-ceramic sealing technology becomes the only reliable solution.
- Core Technology Principle: The core of this technology lies in solving the global challenge of achieving a “rigid connection” between two fundamentally different materials: ceramic and metal. Through special processes such as the active metal method or the molybdenum-manganese method, a metallized layer that can be brazed to the metal is formed on the ceramic surface, thereby achieving a high-strength, airtight seal between the two materials.
- Core Technology Advantages:Unparalleled High-Temperature Resistance: Seals using ceramics such as alumina and silicon carbide can withstand temperatures above 1000℃ for extended periods, with short-term peak temperatures even higher.
- Exceptional Chemical Inertness and Radiation Resistance: High-purity ceramics exhibit excellent resistance to most strong acids, strong alkalis, and organic solvents. Furthermore, it is one of the few sealing materials that can maintain stable performance in nuclear radiation environments.
- High-vacuum sealing: This rigid seal achieves extremely high airtightness standards, making it the ideal choice for maintaining ultra-high vacuum or protecting sensitive cavities in semiconductor chip manufacturing equipment (such asCVD and PVD ), high-energy physics experimental devices, and aerospace vehicles.
This is the ultimate solution designed for “hellish” operating conditions such as nuclear industry filter systems, high-temperature flue gas treatment devices in the chemical industry, aerospace environmental control systems, and semiconductor front-end process equipment. However, its manufacturing cost is high, and it has extremely stringent requirements for installation accuracy and stress uniformity, making it unable to withstand large impacts or bending stresses.
Frankfurt-based filter supplier Trenntech believes that the development of sealing technology has never stopped. Choosing the right sealing technology essentially involves balancing temperature, chemical media, mechanical stress, and cleanliness requirements. This invisible boundary ultimately defines the true level of protective effectiveness.