Explosion-proof cameras play an important role in the field of safety, and are widely used in various fields such as transportation of dangerous goods, monitoring of oil depots in oil fields, chemical industry, pharmacy, etc. due to their intuitive, convenient and extensive application.

China's explosion-proof cameras started in the 1950s and have gone through more than 50 years of development. From the initial agency of foreign products to the present independent production and research, a complete scientific research, design, manufacturing and testing system has been formed.

As far as the explosion-proof principle of explosion-proof cameras is concerned, the explosion-proof principles of mainstream explosion-proof cameras currently on the market are mainly explosion-proof and intrinsically safe.  Flameproof type is widely welcomed by explosion-proof monitoring manufacturers and end users because of its simplicity and easy realization. Please follow the world's science and technology to see what explosion-proof principles and types explosion-proof cameras have in common.

Sparks and arcs can ignite explosive mixtures.  The gap explosion-proof structure established by Germany is a more reliable method to prevent electric arcs and the like from igniting explosive mixtures around.

Flameproof structure electrical equipment is widely used in explosive hazardous areas. It can not only prevent explosion and fire from spreading, but also the shell can withstand certain overpressure.  It has a strong enough shell to withstand the maximum explosion pressure generated by the internal explosive gas mixture to ensure no deformation or damage and no permanent deformation, and has a certain structural clearance to enable the injected combustion products to be cooled to a temperature lower than the spontaneous combustion temperature of the external explosive mixture through a certain flange length.  The structural clearance can be composed of a planar joint surface or a cylindrical joint surface, and can also be composed of curved roads, threads or barrier structures.

Intrinsically safe structures are only suitable for weak current circuits, such as test instruments, control devices and other small electrical equipment.  The electric spark or dangerous temperature generated under normal or abnormal conditions will not cause the explosive substance to detonate, so it is an explosion-proof structure with high safety, in which the surface temperature of all components on the circuit or equipment must be less than the regulation to prevent ignition caused by thermal effect.

The electrical circuit of intrinsically safe explosion-proof structure must be isolated from other circuits to prevent electromagnetic or electrostatic induction of mixed wires. In particular, careful measures must be taken to ensure the explosion-proof performance of electrical equipment and wiring.

Increased safety mechanisms are also widely used in explosion-proof electrical equipment, generally applied to motors, transformers, lamps and electrical equipment with inductive coils, and less applied to explosion-proof cameras.  It adopts a series of safety measures on the equipment, such as using high-quality insulating materials, reducing temperature rise, increasing electrical clearance, improving wire connection quality, etc., to prevent spark, arc or dangerous temperature from being generated to the maximum extent, or adopting effective protection elements to prevent spark, arc or temperature generated from it from igniting explosive mixture, so as to achieve the purpose of explosion prevention.

There is another type of explosion-proof measure similar to the safety-enhancing type called non-sparking type. It is an electrical device that does not generate sparks and dangerous high temperatures during normal operation, nor can it generate detonation failure.  Compared with the safety enhancement type, there is only no provision for adding some additional measures to improve the safety and reliability of the equipment.  Therefore, the safety of non-sparking type is lower than that of increasing safety type, and can only be used in hazardous environment of Zone 2.

The explosion-proof principle of the electrical equipment with this structure is to ensure that the pressure of the internal protective gas is higher than the surrounding to prevent explosive mixture from entering the shell, or sufficient protective gas passes through the shell to reduce the concentration of the internal explosive mixture below the lower explosive limit.

Under normal circumstances, there shall be no ventilation dead angle affecting safety inside the electrical equipment.  During normal operation, the air pressure or inflation pressure at the air outlet shall not be lower than a certain value, otherwise, an alarm will be given immediately or the power supply will be cut off.  Sparks and arcs inside the equipment are not allowed to blow out from any gaps or air outlets.

The positive pressure type structure has nothing to do with the level of explosive substances in use, and is mostly used in equipment with easily damaged internal components or large-scale electrical equipment, or electrical equipment with auto-ignition points T4 and T5, which are difficult to be made into other explosion-proof structure forms.

The explosion-proof oil-filled structure has nothing to do with the explosion transmission grade in use and is suitable for small operation switches.  The filled oil should have high chemical stability. In order to observe the height of the oil level, the equipment should be equipped with an oil level indicator or an oil level signal device.

For switches, controllers and other equipment with oil-immersed explosion-proof structure, it is difficult to repair the equipment due to oil deterioration or leakage, which requires special attention.  In addition, when the explosion-proof performance is damaged due to tilting or oil level shaking, the equipment cannot be used any more.

Sand filling structure is a structure in which sand grains or other powder materials with specified characteristics are filled in the shell, so that the arc or high temperature generated in the shell cannot ignite the surrounding explosive gas environment under the specified use conditions.

When the medium used is granular solid (usually quartz sand) as isolation medium, it is called sand filling electrical equipment.  When the medium used is solidified filler (epoxy resin in general), the ignition source is poured and sealed inside the filler, while when the explosive mixture outside is isolated, it is also called poured and sealed electrical equipment.

Dust explosion-proof electrical equipment is to limit the maximum surface temperature of the enclosure and to limit the dust entry by using a "dust-tight" or "dust-proof" enclosure to prevent ignition of combustible dust.  This kind of equipment installs the live parts in the enclosure with certain protective ability, thus limiting the dust to enter and isolating the ignition source from the dust to prevent the explosion.

Equipment can be divided into Type A equipment or Type B equipment according to the difference of dust-proof structure of the equipment casing.

The equipment is divided into 20, 21 and 22 grades according to the dust-proof grade of the equipment casing, which are applicable to dust hazard sites in 20, 21 or 22 districts respectively.