GJB2805B-2021 National Military Standard for Ventilated Sealed Windows

Technical Specifications

• Airtightness Requirements: The airtight ventilation window must possess excellent airtight performance, such as meeting the GJB2805B-2021 Class 8 airtightness standard, with an air infiltration rate per unit seam length ≤0.5 m³/(m·h). In civil air defense projects, the overall airtightness of the ventilation system, including the airtight ventilation window, must meet relevant testing requirements.

• Protection Level: For anti-theft purposes, the middle layer must use anti-break-in materials, such as steel mesh or anti-theft grilles. The number and strength of fixing points must comply with the "Anti-Theft Level 1" requirement, with anti-prying and digging resistance time ≥25 minutes.

• Moisture Resistance: Seams between layers must be filled with sealant and treated with waterproof strips. Metal components require hot-dip galvanization or anti-corrosion coating, with salt spray test duration ≥1000 hours.

Design Features

• Balanced Ventilation and Airtightness: Features a specific structural design that allows for ventilation when needed while achieving excellent airtightness when necessary. Some designs include adjustable airflow channels, where knobs or similar devices control the volume and direction of air exchange, enabling indoor-to-outdoor or outdoor-to-indoor ventilation.

• Multi-Layer Composite Structure: Typically employs a multi-layer composite structure to meet various functional requirements. For example, airtight ventilation windows designed for scenarios like armory rooms feature a three-layer composite protective structure: an outer steel airtight layer made of 3-4mm thick galvanized or stainless steel plates with multi-point linkage compression devices; a middle ventilation protection layer, which may include anti-theft steel mesh grilles or ventilation louvers with insect screens; and an inner operation and maintenance layer for easy internal operation and upkeep.

• Noise Reduction Function: Some airtight ventilation windows include sound-absorbing rods distributed within the window frame cavity. These rods, made of sound-absorbing cotton material, absorb noise generated during airflow, achieving noise reduction.

• Anti-Condensation Design: During indoor-outdoor air exchange, temperature differences cause moisture in the air to condense. To address this, the first indoor airflow hole, first outdoor airflow hole, second indoor airflow hole, and second outdoor airflow hole are all externally connected to drainage holes, facilitating the discharge of condensate and preventing accumulation.

• Ease of Operation: The operation and maintenance layer is designed for easy daily cleaning or maintenance of ventilation equipment, such as inward-opening casement or sliding panels with lightweight aluminum alloy frames.

Material Requirements

• Outer Layer Materials: If the outer layer is steel, 3-4mm thick galvanized or stainless steel plates can be used to achieve airtight protection and impact resistance.

• Middle Layer Materials: Anti-theft steel mesh grilles are welded with 16mm diameter steel bars, with grid sizes ≤12cm×13cm and fixing point spacing ≤12cm, ensuring high strength and strong anti-prying and digging resistance. Ventilation louvers are typically angled at 45° to prevent rainwater backflow, with an inner cover of 1.5mm stainless steel insect screen and mesh size ≤10×10mm.

• Inner Layer Materials: If the inner layer is an aluminum alloy frame, lightweight aluminum alloy is generally used for ease of operation and maintenance.

• Sealing Materials: Edges are inlaid with EPDM sealing strips or similar materials to achieve "zero-gap" closure, ensuring excellent airtightness.