1. Core Indicator: Airtightness
Controlled atmosphere facilities require strict control of gas components (such as oxygen and carbon dioxide concentrations), so the air conditioning doors must have extremely high airtightness to prevent external air from entering and causing gas fluctuations inside the warehouse.
Test standard: The sealing condition after the air conditioning door is closed must pass a positive pressure test. Typically, a half-pressure drop time test is required when the internal pressure reaches 300Pa (about 30mmH₂O).
Half-pressure drop time: The time it takes for the pressure inside the storage to drop from 300Pa to 150Pa. Industry standards require this time to be no less than 20~30 minutes (some higher standards require ≥ 30 minutes).
2. Thermal Insulation Performance
Controlled atmosphere doors need to maintain the same insulation standards as the cold storage body to prevent cold bridge effects and condensation.
Door leaf material: Usually made of high-density polyurethane (PU) integral foam, with a thickness generally around 100mm, and flame retardant rating typically required to reach B1 level.
Frame and Outer Wrapping: Frames are mostly made entirely of fiberglass or high-strength materials, with exterior materials such as stainless steel or color steel plates to ensure corrosion resistance and strength in low-temperature environments.
3. Sealing and Operation
Special sealing strips: Made with high-quality sealing strips that are pressure-resistant, highly elastic, resistant to low temperatures, and corrosion, ensuring a tight fit even under long-term low temperatures and pressure changes.
Pressing device: A mechanical pressing device must be installed on the door frame. When the door is closed, the door leaf can be pressed tightly against the storage body, ensuring a good seal.
Track design: Often uses multi-bearing straight tracks, making heavy door leaves lighter, more flexible, and less prone to jamming when opening and closing.
4. Safety & Functionality Design
Maintenance door: Since the main gate of the controlled atmosphere storage facility cannot be opened arbitrarily during sealed storage (to avoid disrupting gas balance), a maintenance door (observation door) measuring 600mm wide and 760mm high is usually installed on the controlled gas valve, allowing personnel to monitor the storage status of fruits and vegetables inside the warehouse at any time.
Pressure balance: The air conditioning door and chamber must be paired with a pressure balancing system to handle pressure changes caused by temperature or gas regulation inside the warehouse, ensuring structural safety.