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Structural Design Of Explosion-Proof Lamps

Jan. 23, 2020

In the structural design of flameproof lamps, manufacturers often focus on the shape and strength design of the flameproof enclosure, but often ignore the fasteners, introduction devices, transparent parts, suspension devices, signs, etc. that are integral with the enclosure. Design of other devices. Below, according to the requirements of GB3838.2-2000 "Electrical Equipment for Explosive Gas Environments Part 1: Flameproof Type" d "", china dust explosion proof appliance supplier will analyze what needs attention some problems:

⑴Shell fasteners

There are two types of flameproof enclosures fastened with brass screw caps: flat and stop. For flat structures, bolts not only perform the tightening operation, but also ensure the plane clearance. For the stopper structure, when the flameproof surface only considers the cylindrical part, the bolt only plays a role of fastening; when the flameproof surface needs to consider the cylinder plus the plane, the bolt not only performs the tightening operation, but also ensures the clearance of the plane part. When tapping the thread directly on the shell, you must pay attention: the screw holes of the fasteners should not pass through the flameproof shell as far as possible, and there should be a margin of more than 3mm at the bottom of the screw holes when passing through the shell; when using light alloy materials such as aluminum alloy for insulation When the shell is exploded, due to the low strength of the aluminum alloy, when using a screw to fasten the flameproof shell that is often opened (such as when the light source needs to be opened), the thread should not be directly tapped on the aluminum alloy shell. Internal and external threaded steel sleeves to increase the strength of the screw hole and prevent failure due to rotten teeth; the user does not need to open the light source during replacement or repair, and the bolts already installed at the factory can be directly tapped and tightened on the housing Screw holes, but can not use fine-threaded threads, try to use coarse-threaded threads, and have a sufficient number of engaging buckles to meet the tightening requirements.

In short, when designing shell fasteners, you should first distinguish between its role in the flameproof shell, whether it only plays a role of tightening, or both the role of fastening and the role of ensuring plane clearance, and then determine the maximum axial Use appropriate bolts for the load.

Explosion-proof Wiring Box

Explosion-proof Wiring Box

⑵Introduction method

Cables and wires can be introduced in two ways:

a) Indirect introduction, connection by Explosion-proof Wiring Box or plug-in device;

b) Direct connection, a method of connecting cables and wires directly to the main casing. It is worth noting that when the sealing ring is aged or not tight, it can directly produce combustion or explosion.

Therefore, explosion-proof lamps with dangerous sparks, arcs, or dangerous temperatures and a housing volume greater than 50000px3 or GB3836.1 "Electrical Equipment for Explosive Gas Atmospheres-Part 1: General Requirements" are classified as Class IIC explosion-proof lamps during normal operation. Adopt the elastic sealing ring compression direct introduction method. Although GB3836.2 does not specify this, GB3836.15-2000 "Electrical Equipment for Explosive Gas Atmosphere Part 15: Electrical Installation in Hazardous Locations (Except Coal Mine)" provides for this. The cable introduced into the luminaire through the lead-in device. During the entire process from installation to use, if there is a possibility of tensile force, add a cable pull-out and pressure-relief plate on the compression nut of the lead-in device or near the inside of the luminaire to prevent the force from being transmitted to the terminal Lift and prevent possible movement of the cable, prevent poor contact or failure of the electrical connection. When designing the luminaire, it may be necessary to provide more than one introduction device to facilitate different installation requirements of the user. When leaving the factory, all the lead-in devices should be installed with plugging parts, and the structure of the plugging parts must be suitable for the explosion-proof type. Alternatively, only one lead-in device is installed, and the remaining holes (after the lead-in device is removed) are replaced with a bulkhead suitable for the explosion-proof type. In this way, the failure of the flameproof enclosure will not be caused by forgetting to plug the redundant introduction device.

(3) Installation of transparent parts

Explosion-proof lamps are inseparable from transparent parts, and transparent parts are the lowest-strength parts of the shell components. Therefore, whether the installation of transparent parts is reliable will directly affect the safety performance of explosion-proof lamps.

The following analyzes three commonly used installation methods of transparent parts: a) It is directly sealed in the shell and forms a whole with the shell. This method is simple, practical and widely used. The sealing material should be made of temperature-resistant and oil-resistant rubber parts, or use transparent adhesives such as epoxy resin to seal the transparent parts in the housing and press them tightly.

b) Secure the transparent part directly into the housing with or without a gasket. When the gasket is not used, the flatness of the joint surface of the transparent member is very high. Generally, it is suitable for small flat glass and the glass bonding part is flattened at the same time, otherwise the glass is unevenly stressed and easily broken.

c) sealed or glued to a frame, the frame is fastened in the housing, so that the transparent parts can be replaced as a whole. This structure is rarely used in luminaires. On some large equipment that requires frequent replacement of transparent parts, the transparent part and the frame are replaced as an integral part.

The sealing of the transparent member and the frame can refer to the type of a). In terms of structure, it is necessary to make the force of the transparent member (generated by the internal explosion) directly transmitted to the metal shell. It is not appropriate to transmit the force to the metal shell through the pressure plate and or screw of the transparent member. At the same time, after the transparent member is installed, Can not be stressed, so as to ensure the reliable combination of transparent parts and the shell.

Nanyang Run'an Explosion-proof Electric Appliance Co., Ltd. Applicable Environment

The high-intensity gas discharge lamp is selected as the light source, which has high luminous efficiency and long life, and the average life can be up to 10,000 hours; the power factor is greater than 0.9, the luminous efficiency is high, and the light transmission is good.

Reliable and convenient: high-strength alloy shell, high-tech surface spraying process and sealing treatment, waterproof, dust-proof, wear-resistant and anti-corrosion; can be used for a long time in harsh environments such as high temperature and humidity and various corrosive.