There are two common types of explosion-proof doors used in boilers: swing-type and rupture-diaphragm type.
Swing-type Explosion-proof Doors
A swing-type explosion-proof door is shown in Figure 1. It is a type of explosion-proof door that utilizes a heavy-duty seal. It is generally made of cast iron, with the door cover coated with heat-resistant concrete. The characteristic of this type of door is its automatic reset capability; that is, when the torque generated by the pressure of a gas explosion in the furnace or flue is greater than the torque generated by the door's own weight on the door hinge, the door cover opens; when the pressure is insufficient, it automatically closes.
Swing-type explosion-proof doors are generally installed on the furnace wall of the combustion chamber. These explosion-proof doors can be further divided into vertical and inclined types according to the tilt angle of the door and the vertical direction. Figure 1 shows an inclined swing-type explosion-proof door, with the tilt angle generally not exceeding 30°.
Rupture-diaphragm Type Explosion-proof Doors
A rupture-diaphragm type explosion-proof door consists of a rupture diaphragm and a clamping device, as shown in Figure 2. When an explosion occurs in the combustion chamber, the resulting pressure causes the rupture diaphragm to break, thus releasing pressure. Explosive materials include asbestos and non-ferrous metals such as aluminum and copper, selected based on factors such as pressure and temperature. Currently, asbestos cement board is the most commonly used. Explosive-proof membrane doors are often installed on flues.
