Introduction: during the construction or maintenance of petrochemical projects, the lighting in confined spaces has been bothering the work efficiency of the operators. Lighting used in confined spaces requires high safety, explosion protection, and safe voltage. However, the reactor tower in the larger space and tank container due to the use of safe voltage incandescent light illumination is not up to the job, leading to low efficiency of the limited space, and the risk of working personnel has increased dramatically.

      The LED industry tends to limit its thinking to household lighting, street lighting, rail transit and other general lighting. Instead, there are many special lighting applications waiting to be replaced, such as explosion proof lighting.
　　According to the ElectroniCast Consultant survey report, the global market for explosion-proof products is growing rapidly and the demand is rising. The consumption of global explosion-proof LED lamps and lanterns in 2014 is $160 million 100 thousand, and the estimated global output value in 2021 will be expanded to $273 million 400 thousand.
　　As a result of general LED lighting market margin is low, some Taiwan manufacturers have been restructuring and development, can enhance the profitability of special applications, such as explosion-proof lamps. The current wave of Taiwan petrochemical industry moves ahead with the United States, bringing strong orders for Taiwan. The framework of the Taiwan Long Xin Technology and South photoelectric jump off the traditional industry only focus on the domestic market demand, with the North American market tickets, opened a new page for Taiwan explosion-proof lighting to the international market.

      During the construction or maintenance of petrochemical projects, the lighting in confined spaces has been bothering the work efficiency of the operators. Lighting used in confined spaces requires high safety, explosion protection, and safe voltage. However, the reactor tower in the larger space and tank container due to the use of safe voltage incandescent light illumination is not up to the job, leading to low efficiency of the limited space, and the risk of working personnel has increased dramatically.
　　LED (Light Emitting Diode) as the fourth generation of new light source, which belongs to the solid cold light source, with high conversion efficiency and small heat working voltage is low voltage security, safety and reliability, long service life, energy saving, environmental protection and no pollution, vibration resistance, impact resistance and other excellent properties. It is believed that the use of LED explosion proof light will be an inevitable trend in the operation of confined space in petrochemical industry.

　　1、limited space work lighting deficiencies
　　For a long time, in the construction and maintenance of the petroleum chemical industry, due to the risk of the operation environment is high, operation environment in general are toxic or flammable and explosive substances, and in limited space of light, even without light, the internal environment is complex, the internal structure and irregular, sag uplift place more, more potholes the workers do not enter, convenient operation and operation in the operation period. Therefore, the safe and adequate lighting in confined space is a basic guarantee for the safety of operators.
　　In petroleum and chemical equipment in large equipment installation, cleaning and maintenance are involved in multiple processes, long operation time, high accuracy requirements and clean, often used during the operation before the incandescent lamp is safe voltage as the lighting, but the light intensity is too low, insufficient working environment light, resulting in personnel work low efficiency, time, personnel at the time of growth in dangerous environment, leading to increased risk.
　　Lack of light affects job behavior and work mood more, and further increases operational risk. Due to lack of illuminance, sometimes additional lighting bulbs are added to the lighting during the operation to increase the number of wires in the confined space, which further increases the risk. Furthermore, incandescent lamps produce more heat and further increase risks in the presence of flammable and explosive materials. Although the operation procedure in confined space is perfect, lighting improvement is the first thing to ensure the safe operation of the staff in confined space.

　　2、LED light efficiency advantages
　　The incandescent lamp has a luminous efficiency of around 10 lumens per watt, and most of the power consumption is reduced to heat loss. For white light LED, the luminous efficiency of white light LED has reached 120 lumens / watt, and its light color is good and the spectrum is narrow. Without filtering, it can directly emit colored visible light.
　　Now with 800 thousand tons / year ethylene plant in the region of propylene tower as an example to compute the theoretical average illuminance required required number of lamps, the column internal diameter of 5.6M, installed in the tower, a layer of tray probably need more than 2000 sets of screws, screw the minimum is M10. The operating environment is considered as the working condition under the condition of rough machining, and the illumination is 200lx. According to the lamp, the general suspension height is 3 meters, the space utilization coefficient (CU) is between 0.6-0.75, the maintenance coefficient K takes 0.7, the incandescent light flux is 12lm, and the single LED luminous flux is 100lm. The average illuminance (Eav) = the number of single light flux Phi x lamps (N) by the coefficient of X space (CU) * (K), coefficient of maintenance working area
　　200=12*N1*0.7*0.7÷24.6 N1=837
　　200=100*N2*0.7*0.7÷24.6 N2=100
　　We need incandescent lamps, 837W, and we need 34 3W LED patches. However, the 34 LED white light patches need only be assembled into a LED lamp to achieve theoretical requirements. 100W explosion-proof incandescent lamp needs to install 9 lamps, an explosion proof incandescent lamp, the exterior size is about 150*260, but a LED chip assembly lamp outer diameter 200*150*210 (mm). The 9 incandescent lamps require 9 separate cables to supply power, creating 9 connectors that increase the risk. The LED lights only need one light.

       3、LED explosion-proof lamp explosion-proof performance
　　The basic principle of LED explosion-proof lamp with other explosion-proof lamp, the principle according to the European standard EN13463-1:2002 "explosive environment with non electrical equipment part first: explosion proof fire type and requirements" concept and basic method, is a kind of flameproof explosion-proof type to take steps to allow the internal explosion and prevent flame detonation, is a the most common type of explosion-proof. In addition, many types of flameproof lamps and lanterns, such as power supply, lamp holder and interlock switch, also adopt flameproof structure. Electrical equipment with flameproof enclosure is called flameproof electrical equipment. If the explosive gas mixture enters the flameproof enclosure and is ignited, the flameproof enclosure can withstand the explosion pressure of the internal explosive gas mixture and prevent the internal explosion from spreading to the explosive mixture around the shell. This is a gap explosion-proof principle, propagation and cooling of explosion products using metal gap can prevent explosion flame temperature of flame out and cooling, a structural design principle of explosion suppression expansion.
　　In addition, the LED explosion-proof lamp needs the driving power output is the direct current low voltage, generally cannot produce the electric spark. The principle of the LED lamp is the process of converting electric energy into light energy directly. There is no such phenomenon as converting an electric energy into heat energy as an incandescent lamp, and then increasing the temperature of an object.
　　Incandescent electric energy of 96% heating off, there are a large number of infrared light emitted from the incandescent lamp, 70-80% energy is thermal radiation (IR) in the form of scattered out, 5-10% is in the way of heat conduction transfer to the bulb shell, so the wick temperatures up to 2500 degrees, the outer surface temperature up to more than 200 degrees. LED light rarely contains infrared light, so there is no heat radiation, the chip temperature is more than 200 degrees, and the surface temperature is not felt. At the 100W incandescent 20CM, you can feel the heat very clearly, and the LED light can touch, and you can hardly feel the heat. It is also known as the "solid cold light", will not detonate combustible gas, so LED is the intrinsically safe explosion-proof lamp. This type of explosion-proof, explosion-proof lamp is more secure than other LED explosion-proof lamp.

4、LED explosion-proof lamp safety voltage, current advantages
　　The safety voltage is below 36V, and the harm of electric shock on the human body depends mainly on the size of the current and the duration of the electricity. The greater the current intensity, the greater the risk of death; the longer the duration, the greater the likelihood of death. The minimum current can cause people to feel the value is called the perception of current, 1mA 5mA AC, DC electric energy; the maximum current is called to get rid of herself from the current, so the safety of DC current provision person below 50mA, through the exchange of personal safety current provisions under 10mA. LED light driver power for DC, generally in 6-36V.
　　Generally speaking, AC safety voltage is used for explosion proof incandescent lamps. AC 10mA and DC 50mA current on the human body is dangerous, according to the body resistance of 1200 ohms calculation, the safety voltage is AC 12V DC 60V. Therefore, in the same voltage or the same current situation, LED lamp is more safe and reliable. And the DC low voltage basically does not produce electric spark, and the AC is more likely to produce electrical sparks, so the use of LED lights safer and more reliable.

5、LED explosion-proof lamp energy-saving environmental advantages
　　LED lamp production does not exist such as mercury, lead to environment pollution substance, no stroboscopic and ultraviolet radiation, no glare, no harm to the health of people, LED is a solid luminous body, no filament, no glass bubble, impact resistance is not easy broken, the shell is made of high quality aluminum, corrosion resistant, all waste convenient recycling, recycling, without any other pollutants.
　　Incandescent lamp life is probably about 1000 hours, however, LED lamp life is 100000 hours. This again with ethylene propylene tower installation as an example, if a group of people only one operation total installation period is about 300 days, the total time is about 2700 hours, the use of incandescent lamp and LED lamp 27, only one can be. And the incandescent lamp in use after a period of time, easy filament is burnt out, the light attenuation, because each start is cold start, the instantaneous current is 10-20 times the working current, so the filament is easily burnt off and the LED lamp belongs to every time you start the constant current input, can high frequency operation, so the LED lamp does not exist switching effect on the service life.
　　In front of the need to reach the same intensity of 200lx under the condition of incandescent lamps 837W, LED lamp needs only 100W, achieve the same illumination condition, the incandescent lamp an hour to 0.84 degrees, while the LED lights only 0.1 kwh.

6、Epilogue
　　The state regulations, from October 1, 2012 onwards incandescent lamps larger than 100W, prohibit domestic sales, since October 1, 2014, greater than 60W, prohibit domestic sales, since October 1, 2016, greater than 15W banned domestic sales. Therefore, with the promotion of national policies, incandescent lamps will inevitably be eliminated. The use of LED explosion-proof lighting, high efficiency, small heat, the work voltage is safe, low voltage, safe and reliable, long service life, energy saving, environmental protection, pollution-free, vibration resistance, shock resistance, and other fine features. It is believed that the use of LED explosion proof light will be an inevitable trend in the operation of confined space in petrochemical industry.