Fire insulation clothing is constructed from advanced composite materials, including fiber fabrics and aluminized films. This protective gear includes tops, pants, gloves, hoods, and caps, designed to be asbestos-free, lightweight, strong, flame-resistant, heat-resistant, and capable of withstanding high temperatures and thermal radiation. It also offers excellent wear resistance, fold resistance, and is non-toxic to the human body, providing essential protection for firefighters and workers exposed to extreme heat.
The insulation clothing is typically composed of multiple layers, such as an outer layer, a thermal insulation layer, and a comfort layer. These layers can be combined in single or multiple configurations to meet different protection needs. The outer layer is usually made of a metal foil material that reflects radiant heat, enhancing its protective capabilities.
Insulation suits are tested and certified by the Fire Equipment Quality Supervision and Inspection Center, ensuring compliance with the performance requirements outlined in GA88 "Performance Requirements and Test Methods for Fire Protection Insulation Products." Marine protective clothing is also inspected by the China Classification Society, confirming its reliability in harsh environments.
A positive pressure air breathing apparatus operates by releasing compressed clean air from a gas cylinder through a pressure reducer and a secondary pressure relief valve, delivering it to a full-face mask worn by the user. This system uses an open design, allowing exhaled air to be released directly into the atmosphere, which makes breathing more comfortable due to the high airflow rate. The positive pressure structure ensures that the mask remains at a higher pressure than the surrounding environment, preventing harmful gases from entering the respiratory system. It is reusable, cost-effective, and highly safe, making it a preferred choice for firefighters and rescue personnel. However, its operation time is limited, typically around one hour.
A positive pressure oxygen respirator functions differently. When the user exhales, the gas passes through a full-face mask, an exhalation hose, and an exhalation valve into a clean canister where calcium hydroxide (Ca(OH)₂) absorbs carbon dioxide. The remaining gas then enters an airbag. Compressed oxygen from the gas cylinder is delivered through a high-pressure tube and a pressure reducer, mixing with the gas in the airbag. During inhalation, the oxygen-rich gas flows through an inspiratory valve, a suction hose, and into the mask, completing the breathing cycle. Both the exhalation and inhalation valves are one-way, ensuring unidirectional airflow. The chemical reaction involved is: Ca(OH)₂ + CO₂ → CaCO₃ + H₂O + Q.
Positive pressure oxygen respirators offer longer usage times, typically up to four hours, and maintain a positive pressure inside the mask, preventing harmful gases from entering. This makes them ideal for mine rescue operations. However, they have some drawbacks, such as a closed-loop system that generates heat during COâ‚‚ absorption, leading to discomfort. They also require users to have technical knowledge and proper training, especially when handling absorbents and cooling agents. Additionally, the initial cost is higher compared to other types of breathing apparatus.
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