Deli Innovation class started. Today I will tell you what types of explosion-proof products and equipment there are.

Generally speaking, explosion-proof electrical equipment refers to a class of electrical equipment used in places where there are explosive dangerous gases and vapors and dust; They will not cause dangerous gases or dust in the environment to ignite during operation or failure.

Then have a small partner to worry, plain for no reason how do I know a device is not explosion-proof ah? Should we risk our lives to find out?

At this time, we need experts to specify standards for the inspection and certification of explosion-proof electrical equipment!

At present, the world's main national explosion-proof certification standards are ATEX, IEC, LCIE, UL, NEPSI and PCEC and so on.

So what are the types of explosion-proof products? Let's take a look.

Type of explosion-proof electrical equipment

1 flameproof structure

Electric sparks and arcs can ignite explosive mixtures. The gap flameproof structure established by Germany is a more reliable way to prevent the ignition of explosive mixtures around the arc. The electrical equipment of flameproof structure is widely used in the dangerous area of explosion, which can not only prevent the transmission of explosion fire, but also the shell can withstand a certain overpressure. It has a shell strong enough to withstand 1.5 times and not less than 3.5&times the maximum explosion pressure generated by the internal explosive gas mixture; The impact of 105 Pa ensures no deformation or damage, no permanent deformation, and has a certain structural gap to allow the combustion products ejected to cool below the spontaneous combustion temperature of the external explosive mixture through a certain flange length. The structural gap can be composed of a plane joint or a cylinder joint, and can also be composed of a curved path, a thread or a screen. Other than that. Such as micropores, mesh covers, lamination, sand and other structures also belong to the explosion-proof form of this principle. Flameproof electrical equipment used in coal mines is more robust.

The casing of the equipment used for Class I mining face shall be made of steel plate or cast steel; The shell of Class I non-mining working surface equipment may be made of no less than HT25-47 gray cast iron; For Class I portable devices and Class II devices, the housing may be made of a light alloy with a tensile strength of not less than 117.6N/mm2 (12kg /mm2) and a magnesium content of not more than 0.5% (by weight).

2 Increased safety structure Increased safety mechanism

It is also widely used in explosion-proof electrical equipment, such as motors, transformers, lamps and electrical equipment with inductors. It is the use of a series of safety measures on the equipment, such as the use of high-quality insulation materials, reduce the temperature rise, increase the electrical gap, improve the quality of wire connection, etc., so that it does not produce sparks, arcs or dangerous temperatures within the maximum, or the use of effective protective elements so that the sparks, arcs or temperatures generated by it can not ignite explosive mixtures, in order to achieve the purpose of explosion-proof.

There is also a similar explosion-proof measure with increased safety called non-spark type, which is a kind of electrical equipment that does not produce sparks and dangerous high temperatures during normal operation, and can not produce detonating failures. Compared with the increased safety type, there is only no provision to add some additional measures to improve the safety and reliability of the equipment. Therefore, the safety of the non-spark type is lower than that of the increased safety type, and can only be used in zone 2 hazardous environments.

3 Positive pressure type structure

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

Under normal circumstances, there must be no ventilation dead Angle inside the electrical equipment that affects the safety. During normal operation, the wind pressure or inflation pressure of the outlet shall not be lower than a certain value, otherwise an alarm will be issued immediately or the power supply will be cut off. The spark and arc inside the equipment are not allowed to blow out from any gap or outlet.

The positive pressure structure has nothing to do with the level of explosive quality in use, and is mostly used on equipment or large electrical equipment whose internal components are easily damaged, or on electrical equipment whose spontaneous combustion point is T4 and T5, which is difficult to make into other explosion-proof structural forms.

4 Sand filling structure

Sand filled structure is the shell filled with sand or other powder materials with specified characteristics, so that under the specified conditions of use, the arc or high temperature generated in the shell can not ignite the surrounding explosive gas environment structure.

When the medium used is a granular solid (generally quartz sand) as the isolation medium, it is called sand-filled electrical equipment; The medium used is the solidified material filler (generally epoxy resin), the ignition source is sealed inside the filler, and the explosive mixture is isolated from the outside, also known as the sealing type electrical equipment.

5 Intrinsically safe structure

The intrinsically safe structure is only suitable for weak current circuits, such as test instruments, control devices and other small electrical equipment. Whether it is under normal circumstances, or under abnormal circumstances, the electrical spark or dangerous temperature will not cause the explosive substance to detonate, so that the safety of the explosion-proof structure, in which the circuit or equipment on the surface of all components must be less than the specified temperature to prevent the ignition caused by thermal effects.

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

6 explosion-proof oil-filled structure

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

The switch, controller and other equipment of oil-immersed explosion-proof structure, due to the deterioration or leakage of oil and other reasons, equipment damage is difficult to repair, and special attention is needed. In addition, when the explosion-proof performance is damaged due to tilt or oil level shaking, the equipment can no longer be used.

7 Explosion-proof structure in explosive dust environment

Dust explosion-proof electrical equipment is used to limit the maximum surface temperature of the enclosure and adopt “ Dust density ” Or “ Dustproof ” Housing to restrict dust entry to prevent combustible dust from igniting. This type of equipment installs the live parts in a protective housing, thus limiting the entry of dust, so that the ignition source and dust isolation to prevent the generation of explosion. The equipment is divided into type A equipment or type B equipment according to the difference in the dustproof structure of the equipment. According to the dust level of the equipment shell, the equipment is divided into 20, 21 and 22 grades, which are suitable for dust hazardous places in 20, 21 or 22 zones, respectively.