What are the structure and requirements of an explosion-proof positive pressure cabinet?

Under the control of an automatic control system, the explosion-proof pressurized cabinet introduces a protective gas, creating a micro-positive pressure environment inside the positive pressure chamber where the pressure is higher than that outside. This prevents combustible hazardous gases from entering the positive pressure chamber, ensuring the safe operation of internal standard instruments and electrical components. Explosion-proof pressurized cabinets can be classified into specialized types for specific industries based on differences in structure, function, and positive pressure protection methods. Whether used in special industries or other applications, explosion-proof pressurized cabinets must comply with universal explosion-proof structural and safety requirements.
Structural Materials In explosion-proof pressurized cabinets, the outer shell is often referred to as the "positive pressure enclosure," which is the main component. Typically, the positive pressure enclosure is made of steel plates or stainless steel materials (such as 304 stainless steel). The positive pressure enclosure must possess sufficient mechanical strength, and both the enclosure and its delivery pipelines and connecting components must meet the test pressure values specified by explosion-proof standards without deformation or damage. The explosion-proof pressurized cabinet should be equipped with an automatic safety device inside to limit pressure when it becomes too high, preventing damage to the cabinet. Doors and Covers of Explosion-Proof Pressurized Cabinets The doors and covers of explosion-proof pressurized cabinets must be interlocked with the electrical circuit. When the door or cover is opened, the power supply to non-explosion-proof electrical components inside the cabinet should be automatically cut off. Power cannot be restored to these non-explosion-proof components until the door or cover is securely closed.
Air Inlet and Outlet The positions of the protective gas inlet and outlet on the explosion-proof pressurized cabinet are determined based on the specific gravity of the protective gas. When the protective gas is heavier than air, the inlet is located at the top of the cabinet, and the outlet is at the bottom. When the protective gas is lighter than air, the inlet is at the bottom, and the outlet is at the top. Both the inlet and outlet should be positioned opposite each other to facilitate gas flow and purging. Installation of Baffle Tubes To ensure thorough purging airflow reaches every corner inside the explosion-proof pressurized cabinet, baffle tubes should be used to improve the purging effect of the protective gas. Spark and Hot Particle Baffles Should Be Added When the outlet of the explosion-proof pressurized cabinet is located in a gaseous environment, baffles should be installed inside the enclosure to prevent hot particles and potential discharge sparks from escaping through the outlet into the surrounding environment.
Protection of Explosion-Proof Pressurized Cabinets To maintain a positive pressure inside the cabinet higher than the external pressure during normal operation, in addition to the necessary gas inflow, the cabinet must have good sealing to prevent leakage of the protective gas and a drop in internal pressure. On-Site Requirements for Explosion-Proof Pressurized Cabinets 1. Installation location of the cabinet: Indoors or outdoors under a shelter, on a flat surface without significant vibration. Wiring methods include cable trench wiring or steel pipe wiring. The grounding wire must be connected to the dedicated grounding screw as required. 2. During transportation and installation, severe tilting is strictly prohibited. Prying or hammering methods must not be used for moving the cabinet. 3. The flow rate and pressure value of the inlet must be within the specified range. 4. The site must have a safe and clean gas source (compressed air).