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With the rapid development of petroleum, chemical, and mining industries, lighting fixtures are increasingly used in production, warehousing, and rescue. How to prevent accidental explosion of lighting fixtures has become a very important issue in explosive gas hazardous locations. As the lighting fixtures inevitably generate sparks or form hot surfaces when they work, once they meet the explosive gas mixture at the production or rescue site, it will lead to an explosion accident that will directly endanger the lives of national property and citizens. Therefore, as the most widely used lighting fixture, its explosion-proof technology has long attracted people's attention and great attention. Aluminum alloy shell, surface spray; lighting, emergency dual-use; built-in maintenance-free nickel-cadmium battery pack, automatic charging under normal power supply, accident power failure or power failure, automatic lighting of emergency lights; steel pipe wiring; emergency special lights in normal The lighting and emergency lighting are independent; the lighting emergency dual-purpose lamp, normal lighting and emergency lighting share one lamp body and the light source is independent.
Categories <br> <br> explosion proof lamp lights glare is generally selected by a light source explosion-proof structure type, use classification. According to the light source classification, there are explosion-proof incandescent lamp, explosion-proof high-pressure mercury lamp, explosion-proof low-voltage fluorescent lamp, mixed light source lamp, etc.; according to the explosion-proof structure type, there are explosion-proof lamps, increased safety lamps, composite lamps, etc.; Explosion-proof lamps and portable explosion-proof lamps.
According to the explosion-proof type, the explosion-proof type can be divided into 5 types: explosion-proof, increased safety, positive pressure, non-sparking and dust explosion-proof. It can also be combined or combined by other explosion-proof types and the above explosion-proof types. And special type.
According to the type of protection against electric shock, the type of protection against electric shock can be divided into I, II, and III categories. The protection against electric shock is to prevent the explosion-proof lamp housing from being easily touched and the parts are electrified, so that the human body is exposed to electric shock or conductors with different potentials to generate electric sparks and ignite the explosive mixture.
AI class—On the basis of basic insulation, accessible conductive parts that are not energized during normal operation are connected to the protective ground conductor in the fixed line.
Class BII - Use double insulation or reinforced insulation as a safety measure without grounding protection.
Class CIII - Use a safe voltage with an effective value of not more than 50V, and no voltage above it will be generated.
Category D0 - only rely on basic insulation as a safety protection measure.
The vast majority of explosion-proof lamps are protected against electric shock by type I and category lamps, and only a few are Type II and Type III lamps. For example: all plastic explosion-proof lamps, explosion-proof flashlight Jane.
Type symbol Principles of explosion protection flameproof d <br> <br>
The components of the device that may ignite the explosive gas mixture are all enclosed within a housing that is capable of withstanding any interface or structural gap through the housing. The flammable mixture that has penetrated into the interior of the device explodes without damage and ensures internal The flame gas reduces energy when propagating through the gap and is not enough to detonate the shell gas.
Zeng Anxing e
Electrical equipment that does not produce arcs or sparks under normal operating conditions will take additional measures to increase its safety and prevent explosions of the possibility of dangerous temperatures, arcs and sparks in its internal and external components. Protection measures to improve equipment reliability and safety performance.
Positive pressure type p
By keeping the pressure of the protective gas inside the device enclosure higher than the surrounding explosion-proof ambient pressure to a safe electrical device, a positive static pressure is maintained inside the system or a continuous flow of air or inert gas is maintained to restrict entry of the flammable mixture into the interior of the enclosure. The flammable gas that enters the enclosure when the device is in a non-positive pressure state is taken away to prevent the formation of a flammable mixture in the enclosure.
This placement I
All circuits inside the equipment are intrinsically safe circuits of the explosion-proof gas atmosphere that are not specified by any spark or any effect under standard conditions (including normal operation and specified fault conditions).
Casting type m
Explosive sparks, arcs, or dangerous temperature electrical components that may ignite the explosive mixture will be encapsulated in the encapsulant (composite) so that it cannot ignite the surrounding explosive mixture. Enclosure measures are used to prevent electrical components. Short-circuiting, solidification of electrical insulation, avoidance of sparks on the circuit, ignition of arcs and dangerous temperatures, prevention of intrusion of explosive mixtures, control of surface temperatures under normal and fault conditions.
Oil-immersed type o
The entire equipment or components of the equipment are invaded in the oil I protection fluid l so that it cannot ignite the explosion-proof gas environment above the oil surface or outside the housing.
Sand filling type q
The shell is filled with sand or other powder material of specified characteristics so that, under the specified conditions of use, arcs or high temperatures generated in the shell cannot ignite the type of electrical equipment protection of the surrounding explosive gas atmosphere.
Airtight Type h This type of explosion-proof equipment uses a hermetic enclosure. That is, the explosive gas mixture in the environment cannot invade the inside of the device housing. The airtight enclosure is sealed by melting, squeezing or gluing. This enclosure is mostly non-detachable to ensure permanent tightness.
Classified according to the degree of protection of the enclosure according to the degree of protection of the enclosure: in order to protect the dust, solid foreign matter and water from entering the lamp cavity, touching or accumulating on live parts to produce flashover, short circuit or damage to electrical insulation, there are a variety of shell protection Plays a role in protecting electrical insulation. The characteristic letter “IP†followed by two digits is used to characterize its enclosure protection level. The first number indicates the protection against humans, solid objects or dust. Divided into 0-6 levels. Explosion-proof lamps are sealed lamps. Their dust-proof capacity is at least 4 levels. The second number represents the protection against water and is divided into 0-8 grades.
According to the support surface material, the design of the support surface material according to the luminaire classification: Indoor explosion-proof luminaires may be installed on the surface of many ordinary combustible materials, such as wooden walls and ceilings, which do not allow the temperature of the explosion-proof luminaire installation surface to exceed the safety value. According to whether explosion-proof lamps can be installed directly on the surface of ordinary combustible materials, they can be classified into two categories.
One category is lamps that are only suitable for installation on non-flammable surfaces.
The other category is lamps that are suitable for direct installation on the surface of ordinary combustible materials and are marked with symbols.
In addition, according to the form of installation can be divided into fixed, portable, portable.
Principle Principle <br> <br> flameproof according to European standard EN13463-1: 2002 "Electrical equipment for explosive atmospheres non Part 1: Basic methods and requirements," the concept of explosion and fire type, flameproof is to take measures to permit An explosion-proof type that explodes inside and prevents flame propagation is the most commonly used explosion-proof type. Since the explosion-proof type lamp housing is generally made of a metal material, the heat dissipation is good, the strength of the housing is high and the durability is good, and it is very popular with users. Moreover, many increased safety explosion-proof lighting components, such as lamp holders, interlock switches, etc., are also flameproof structures. An electrical device with a flameproof enclosure is called a flameproof electrical device. If the explosive gas mixture enters the flameproof enclosure and is ignited, the flameproof enclosure can withstand the explosive pressure of the internal explosive gas mixture and prevent the internal explosion from propagating to the explosive mixture around the enclosure. This is a kind of clearance explosion-proof principle, that is, a structure designed by using the metal gap to prevent the propagation of the explosion flame and cool down the temperature of the explosion product, achieve flame extinction and temperature reduction, and suppress the expansion of the explosion principle.
Design <br> <br> performing proof luminaire structural design, manufacturers tend to focus on the design of the shape and strength of the flameproof enclosure, but often overlooked fastener integral with the enclosure, introduction means, transparent Parts, suspensions, signs, and other devices. Next, according to the requirements of GB3838.2-2000 “Electrical Equipment for Explosive Gas Environments Part 1: Flameproof Type “dâ€â€, some problems that need attention should be analyzed in terms of structural design:
(1) Case Fasteners There are two types of flameproof enclosures that are fastened with bolts: flat and spigot. For flat structures, the bolts not only perform tightening operations, but also ensure the plane clearance. For the stop structure, when the flameproof surface only considers the cylinder part, the bolt only plays a fastening role; when the flameproof surface needs to consider the cylinder plus the plane, the bolt not only performs the fastening work, but also plays the role of ensuring the clearance of the plane part. When tapping directly on the shell, attention must be paid to the following: Screw holes of the fasteners should not pass through the flameproof enclosure as much as possible, and 3mm or more of the margin should be left at the bottom of the screw hole when passing through the shell; light alloy materials such as aluminum alloy are used to separate the bolts. When blasting the shell, due to the low strength of the aluminum alloy, when using the screws to fasten the explosion-proof shell that is often opened (if the replacement light source needs to be opened), tapping should not be performed directly on the aluminum alloy shell; The internal and external thread steel sleeves are used to increase the screw hole strength and prevent failure due to thread rotting; it is not necessary for the user to open the replacement light source or maintenance, and the bolts already installed at the factory can be tapped directly on the shell. Screw hole, but can not use fine thread, try to use coarse thread, and there is enough engagement to meet the fastening requirements.
In short, in the design of shell fasteners, it should first distinguish its role in the flameproof enclosure, is only to play a role in fastening, or both to play at the same time to ensure the role of plane clearance, and then determine the maximum axial bolt Use suitable bolts for the load.
(2) Introduction The introduction of cables and wires can be connected by the following two methods:
a) indirect introduction, connection by junction box or plug-in device;
b) Directly introduce the connection of cables and wires directly to the main housing. It is worth noting that the seal can burn or explode directly when the aging or pressure is not tight.
Therefore, explosion-proof lamps classified as Class IIC are not suitable for generating dangerous sparks, arcs, or dangerous temperatures during normal operation and the enclosure volume is greater than 2000 cm3 or GB3836.1 “Electrical Equipment for Explosive Gas Environments Part 1: General Requirementsâ€. The elastic sealing ring presses the direct introduction method. Although GB3836.2 does not describe this, GB3836.15-2000 “Electrical Equipment for Explosive Gas Environments Part 15: Electrical Installation in Hazardous Locations (Excluding Coal Mines)†regulates this. Through the cable introduced into the fixture through the introduction device, from the installation to the use of the entire process, if possible to be subject to tension, the introduction of the device on the compression nut or close to the lead device inside the fixture to increase the cable pull-out pressure plate to prevent the force transmitted to the terminal block Prevents possible movement of the cable and prevents contact or failure of the electrical connection. Lamps may need to be provided with more than one lead-in device at design time to facilitate different installation requirements of the user. All sealing devices shall be installed at the time of shipment from the factory. The structure of the sealing device must be suitable for explosion protection. Alternatively, only one lead-in device is installed, and the remaining holes (after removal of the lead-in device) are replaced by plugs suitable for explosion protection. In this way, the failure of the flameproof enclosure will not be caused by the unintended plugging of the lead-in device.
(3) The installation of transparent parts Explosion-proof lamps can not be separated from transparent parts, and transparent parts are the components with the lowest strength in the shell parts. Therefore, the installation of transparent parts directly affects the safety performance of explosion-proof lamps.
The following analysis of three commonly used transparent parts installation: transparent parts a) sealed directly in the shell, and the shell to form a whole. This method is simple, practical and widely used. Sealing materials should be selected from rubber parts that are resistant to temperature and oil, or adhesives such as epoxy resin can be used to seal the transparent parts in the housing and press them tightly.
b) Secure the transparent member directly in the housing with or without a gasket. The flatness of the bonding surface of the transparent member is not required when the gasket is not used, and is generally suitable for a small flat glass and the glass bonding portion is polished at the same time. Otherwise, the glass is not uniformly subjected to stress and is easily broken.
c) Sealed or glued to a frame that is secured within the housing so that the transparent member can be replaced as a whole. This kind of structure is rarely used in luminaires. In some large devices that require frequent replacement of transparent parts, the transparent parts and the frame are replaced as a single unit.
The sealing of the transparent member and the frame can refer to the type of a). In terms of structure, the force (inner explosion) received by the transparent member should be transmitted to the metal shell as much as possible. Passing the transparent platen and/or screws to the metal shell is not appropriate. At the same time, the transparent member is installed. Can not be subjected to stress, so as to ensure reliable combination of transparent parts and shell.
Selection <br> <br> explosion-proof lighting selection, installation, use and maintenance are to protect the long-term safety explosion-proof lighting, reliable and efficient work indispensable part, must be sufficient attention.
1 The selection personnel must understand the basic working principle of the explosion-proof lamps, and be familiar with the explosion-proof signs.
2According to the level of explosive hazardous locations, accurately select the type of explosion-proof lighting, type, level and temperature groups.
3 understand the use of environmental conditions and work requirements, reasonable selection of explosion-proof lamps and lanterns with various functions. For example: The explosion-proof lamps and lanterns used outdoors have a degree of protection of at least IP43. In locations where color is required to be identified, high-pressure mercury lamps and high-pressure sodium lamps may not be used as explosion-proof lamps because the color rendering of the two light sources is poor.
4 Read the product instruction manual in detail to understand the product performance, precautions, and product limitations, and to understand the contents of all product symbols. If the explosion-proof certificate number is followed by an "x" symbol, it indicates that the lamp has a specific applicable location. The product instruction manual and nameplate should be consulted to clarify the applicable site requirements.
Although incandescent light sources are still widely used, they are being gradually replaced by other light sources because of their low luminous efficiency and short lifetime. Among them, single-plug non-starter fluorescent lamps, self-ballasted high-pressure mercury lamps, and high-pressure sodium lamps are widely used.
Single-plug non-starter fluorescent lamp is a kind of cold cathode gas discharge lamp. The principle of light emission is to use the discharge between the electrodes to make the mercury atoms generate ultraviolet radiation, thereby igniting the fluorescent substance on the inner wall of the lamp tube. This fluorescent lamp has a high luminous efficiency (about three times that of incandescent lamps) and has a long service life. It does not require a starter when starting (usually a conductive layer on the lamp tube wall, called the glow layer, the fluorescent lamp Rely on it to complete; when the lamp is broken, the glow layer is also destroyed, the lamp is extinguished), and the cathode temperature is low (about 200°C or so), which is a safe and practical light source, and is very suitable for making increased safety lighting fixtures. . Environmentally-friendly light source Self-ballasted high-pressure mercury lamp is a hybrid light source that utilizes high-pressure mercury vapor discharge and light emission of incandescent body and fluorescent substance. It has the advantages of high brightness, simple structure, fast starting speed and so on. The disadvantages of external ballasts need to be changed in previous high-pressure mercury lamps, and tungsten filaments are used to limit the flow, and light color is also improved. The disadvantage is that the lifetime is shortened compared to ordinary fluorescent high-pressure mercury lamps. The high-pressure sodium lamp is a high-pressure sodium vapor discharge lamp, which has the advantages of high luminous efficiency, low power consumption, strong fogging ability, long service life, and the like.
Single-plug non-starter fluorescent lamps and self-ballasted high-pressure mercury lamps are now mainly used in production plants. The original fixed explosion-proof incandescent lamp, in the case of meeting the minimum distance between the lamp and the transparent cover as stipulated in the regulations, has been replaced by the self-ballasted high-pressure mercury bulb of the original lamp and approved by the relevant unit. Although high-pressure sodium lamps have a certain energy-saving effect, due to their poor color rendering, we generally do not use them in production facilities and only use it in road lighting. Sometimes, in order to improve the white light color emitted by the high-pressure mercury lamp, some high-pressure sodium lamps may also be incorporated in the production device. For high-intensity lighting sites that require good color rendering (such as the on-site inspection of large-scale unit equipment), explosion-proof floodlights can be used. The light sources are generally metal halide lamps, and the rated power can reach more than 1000W.
The explosion-proof structure type of the explosion-proof structure type explosion-proof lamp shall be determined according to the regional level and scope of the explosive gas environment. For example, explosion-proof lamps must be used within the scope of zone 1. The fixed lamps in zone 2 can be explosion-proof and increased safety. Lamps must be flameproof. The level or group of explosion-proof lamps selected should not be lower than the explosion mixture level and group in explosion hazardous environments. At the same time, the impact of the environment on explosion-proof lamps should be taken into consideration, and the requirements of various environments such as ambient temperature, air humidity, corrosion, or contaminating substances should be met. According to different environmental requirements, the lighting protection level and the corrosion protection level should be selected. Especially in the presence of corrosive gases in explosive gas atmospheres, it is crucial to select lamps with corresponding corrosion resistance.
In the past, among the petrochemical enterprises, the lighting fixtures in explosion hazardous locations were mainly flameproof. With the increasing use of increased safety electrical equipment in explosion hazardous locations in Zone 2, increased safety and composite lighting fixtures are also being used more and more. The increased safety type luminaire has the advantages of light weight, low price, convenient installation and maintenance, long service life, etc. compared with the flameproof type lamps on the basis of certain explosion-proof performance. The most widely used composite electrical equipment used in petrochemical enterprises is the Zengan-explosion-proof compound type explosion-proof electrical equipment. It is generally composed of three parts: explosion-proof components, increased-safety terminal blocks, and increased safety enclosures. It has both flameproof safety. Performance, but also has the advantage of increased safety.
<br> <br> proof lamp mounted in the collation from the plate before mounting the product specification: explosion-proof type, class, grade, group; housing degree of protection; Installation and mounting requirements of fasteners. The installation of explosion-proof lights must be securely secured, the fastening bolts must not be replaced, and the spring washers should be complete. The dust-proof and waterproof seals should be placed as they are. When the cable enters the line, the cable and the sealing gasket should be closely matched. The section of the cable should be round, and the surface of the jacket should not have defects such as asperities. Extra inlets shall be sealed in accordance with the type of explosion protection, and tighten the compression nut to seal the inlet.
Maintenance and repair <br> <br> in the daily repair and maintenance, the need to pay attention to the following points.
Explosion-proof lights and lampshades should be able to automatically cut off the power before they are opened. However, due to the complexity of setting up the interlocking device, it is difficult to implement. Therefore, most lamps and lanterns only have warning signs such as “No live-on†on the obvious part of the enclosure. Because the surface temperature of the bulb is still high after power off, if you open the lampshade immediately, there is still the danger of igniting the explosive gas mixture (mainly flameproof structure). Therefore, the surface temperature of the incandescent lamp, high pressure mercury lamp, and high pressure sodium lamp are high. , but also quickly open the lid of the luminaire to pay attention to this. The use of more CeY-1 explosion-proof fluorescent lamps by the company's unit has an interlock mechanism that opens and closes the power supply, providing convenience and safety for maintenance work. Because the fluorescent lamp is a cold light source lamp, there is no surface high temperature, and the lid can be opened immediately after the power is turned off.
When replacing the bulb (tube), the explosion-proof lamp's flameproof joint shall be properly protected and shall not be damaged; the cleaned explosion-proof surface shall be coated with phosphated plaster or 204-1 anti-rust oil; other paints shall be prohibited from painting; There shall be no rust layer on the surface. If there is slight rust, there shall be no numbness after cleaning. The seals used for dust protection and waterproofing must be kept intact. This is very important for the increased safety lighting. If the seal is seriously damaged, replace it with a seal of the same size and material and replace the entire light if necessary. When overhauling, pay attention to whether the lampshade is intact and replace it immediately if it is broken.
Explosion-proof lamps and lanterns should be maintained regularly and in time during use.
1 Maintenance and repair personnel need to be trained on the job to understand the performance of the lamps and use requirements clearly. Maintenance personnel must have professional knowledge and be familiar with the structure of the lighting products.
2 Regularly eliminate dust and dirt on the explosion-proof lamp housing and improve the light efficiency and heat dissipation performance of the lamp. The cleaning method can be based on the protection capability of the lamp housing, using water spray (over the shade on the lamp) or using a damp cloth. When cleaning with water spray, the power should be cut off. Do not use a dry cloth to scrub the plastic housing (transparent parts) of the lamp to prevent static electricity.
3 Check whether the plastic casing (transparent parts) of the lamp has serious discoloration, such as severe discoloration, indicating that the plastic has aged. Check whether the transparent parts have been affected by foreign material, whether the protection network has loosened, soldered, and corroded. If so, use should be stopped and repaired and replaced in time.
4 The light source should be turned off in a timely manner to notify the replacement, so as to prevent the ballast and other electrical components from being in an abnormal state for a long time because the light source cannot be started.
5 If the accumulated water in the cavity of the lamp used in the humid environment should be cleared in time, replace the sealing parts to ensure the protective performance of the housing.
6 When you open the lamp cover, you should press the warning board to open the cover after turning off the power.
7 After opening the cover, check whether the flameproof joint surface is intact, whether the rubber seal is hardened or sticky, whether the wire insulation layer is green and carbonized, and whether the insulation and electrical components are deformed and burned. If these problems are found, they should be promptly repaired and replaced.
8 Maintenance The model, size, size, and performance of the replaced light source, components, and electrical components should be the same as those of the light source, components, and electrical components prior to service and replacement.
9 Apply wet cloth (not too wet) before closing the cover. Lightly tap the light and transparent parts of the lamp to increase the efficacy of the lamp. A layer of 204-1 displacement rust preventive oil should be applied thinly on the flameproof joint surface. When the lid is closed, attention should be paid to whether the sealing ring plays a sealing role in the original position.
10 The sealed part of the lamp should not be frequently disassembled and opened.
Note <br> <br> portable lamps fed into the power grid and its own power supply two kinds. For lamps powered by the feed-in network, rubber-sleeved cables shall be used between the explosion-proof junction boxes (boxes) or explosion-proof plugs and the lamps. The grounding or connection of the neutral conductor shall be within the same jacket; the cable shall adopt the minimum allowable cross section of the main conductor core. 25 mm2 YC, YCW heavy duty rubber cable. One point to be emphasized here: The cable for portable lighting does not allow intermediate connectors.
In the electrical explosion-proof safety management, there can be no luck mentality, and it must be done in strict accordance with relevant regulations and requirements in order to be foolproof.
Some common sense about explosion-proof lighting
Explosion light refers to the dangerous place where flammable gas and dust are present. It can prevent arcs, sparks and high temperatures inside the lamp from igniting flammable gas and dust in the surrounding environment, thereby reaching the explosion-proof requirement. Also known as explosion-proof lighting, explosion-proof lighting. Different flammable gas mixture environments have different requirements for the explosion-proof grade and explosion-proof form of explosion-proof lamps. Specific reference GB3836, IEC60079.