An explosion-proof door is an anti-explosion protective device designed to withstand accidental explosions occurring outside industrial buildings, thereby safeguarding human life and preserving the integrity of equipment inside the building from the damaging effects of blast waves and effectively preventing the propagation of explosion-related hazards. It is fabricated from specialized industrial steel plates according to rigorously defined mechanical performance parameters and equipped with high-performance hardware components, ensuring the safety of lives and property. The explosion-proof door is specifically engineered to resist unexpected external explosions, protect personnel safety, maintain the integrity of internal equipment, shield against blast wave damage, and effectively contain and mitigate the spread of explosion-related harm. Constructed from premium industrial steel plates in accordance with stringent mechanical specifications and fitted with top-grade hardware, it offers both practical functionality and aesthetic appeal, further enhancing its role in protecting lives and property. Explosion-proof doors are also referred to as blast-resistant doors. They are available in two main types: swing-type and rupture-membrane-type.
(1) Swing-type explosion-proof door:
The swing-type explosion-proof door is shown in Figure 1. It is a type of explosion-proof door that relies on its own weight for sealing; the typical material is cast iron, and the door cover is coated with heat-resistant concrete. A distinctive feature of this type of door is its ability to automatically reset: when the moment generated by the pressure of a gas explosion in the furnace chamber or flue exceeds the moment produced by the door’s self-weight about the hinge axis, the door cover opens; when the pressure is insufficient, the door automatically closes again. Figure 1: Swing-Type Explosion-Proof Door. Figure 1: Swing-Type Explosion-Proof Door. Swing-type explosion-proof doors are generally installed on the furnace wall of the combustion chamber. Based on the inclination angle between the door and the vertical, they can be further classified into vertical and inclined types. As shown in Figure 1, this is an inclined swing-type explosion-proof door, with an inclination angle typically not exceeding 30°.
(2) Blast-Resistant Diaphragm-Type Explosion-Relief Doors
The rupture-diaphragm type explosion vent consists of a rupture diaphragm and a clamping mechanism, as shown in Figure 2. When an explosion occurs in the combustion chamber, the resulting pressure causes the rupture diaphragm to fail, thereby relieving excess pressure. Rupture materials include asbestos, aluminum, copper, and other nonferrous metals; the specific material is selected based on factors such as pressure and temperature. Currently, asbestos-cement boards are most commonly used. Rupture-diaphragm type explosion vents are typically installed on flue ducts. The requirements for explosion vents are as follows:

(1) Explosion-proof doors shall be installed in the combustion chamber, at the furnace outlet, in the economizer flue, in the flue upstream of the induced-draft fan, in the horizontal flue downstream of the induced-draft fan, or in any flue with a slope greater than 30°.

(2) Explosion-proof doors shall be installed in locations that do not pose a threat to the safety of operating personnel and shall be equipped with pressure-relief guide pipes; flammable and explosive materials shall not be stored in the vicinity.

(3) The emergency explosion-proof door must be manually tested and inspected on a regular basis to prevent it from rusting shut.

[2] Functions and advantages:

1. In the event of an explosion, the blast door is designed to withstand the predicted incident pressure and reflected pressure, thereby providing the necessary protection within this pressure range and preventing casualties and property damage.

2. Even after an explosion occurs, if the explosive force does not reach the pre-set threshold, the explosion-proof door can still function normally.

3. In the event of an explosion, once the explosive force reaches a pre-set threshold, the door may deform; however, its components shall remain functional to prevent personnel from being trapped or confined.

4. Essential airtight isolation functionality to prevent direct air convection between the isolated space and the external environment, thereby reducing contamination of the isolated and protected space from external sources.

5. An explosion-proof door is a safety device that features self-closing and emergency egress functions.

6. Common blast-resistant door ratings for shock waves are: 0.19 MPa = 190 kPa, and 0.11 MPa = 110 kPa.