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Common cause of air-conditioners fire and prevention measures

28-12-10 15:49    Click:

       With the daily growth of national economy , when the hot seasons of summer and autumn come on, air conditioners become household, accordingly, the number of fire caused by air conditioners also increase, threatening people's lives and property. In light of my practical work, i would like to talk about the common causes of air conditioner fires and preventive measures.
一、 Common causes of air conditioner fires
       Air conditioners, by its functions, are divided into such two types as electric power and electric heating, one can only refrigerate air, the other can cool and heat air. An air conditioner consists of three parts: first, a refrigeration system (with a motor-driven compressors); second, a ventilation circulation system (including the fan motor, centrifugal fan and pump flow fan, etc.); third, the electrical control system. Air conditioner fires are mainly caused by:
       1. the installation does not meet the requirements:
(1) poor or loose connection of the power cord with the motor connector, overheating ignition set the combustible plastic shell of air conditioner on fire; (2) the cross-sectional area of selected conductor is too small to cause overload fire; (3) the selected plug with low-voltage can only withstand small capacity, resulting in breakdown and short circuit fire; (4) the fuse does not match with the air conditioner capacity, when the fuse cannot be melted when failure happens; (5) wrong hookup with power causes fire. For instance, window air conditioner usually uses single-phase 220 volt power supply and single-phase three-wire plug which is likely to be mistaken for three-phase 380-volt power supply, then wrong hookup leads to fire; (6) improper installation location. The air conditioner is installed on combustible members, too close to curtains, wood structure and other objects, or installed at humid location without moisture treatment or enough covered area. In summer, air-conditioning condenser are in sunlight for too long, when at noon , its temperature goes up to above 40 ℃, the non-stop operation of air conditioner leads to overheating of compressor and frequent operation of overload protection device, resulting in compressor burndown or circuit fire.
       2、The fan of electric-heating type air conditioner stops. Fan stops rotating for two reasons: First, a failure occurs to the air-conditioner itself, for example, the fan blades eccentrically rotate due to bearing wearing, the blades jam up the casing, causing the stop of fan; Second, the fan and heater are controlled by different switches, when the air conditioning unit is turned of, the power of electric part is not cut off. If the fan stops and the large heat accumulates, the temperature rises, which is likely to ignite combustibles near the heating pipes.
       3、high temperature spark generated when oil capacitor is broken down ignates insider liner and dividers of casing. The causes of capacitor breakdown are: First, the supply voltage is too high; second, moisture leakage, poor capacitors, insulating properties compromised with moisture, increased leakage current, leading to breakdown.
       4、 Improper use
(1)the user does not operate the electric air conditioner according to the specifications required. When the user stops the heating, there is no ventilation position for the cooling of electric part. Because the thermal inertia of electric wire is large, when the electric air conditioners is cut off power, if no fan operates to cool, then for a long period of time the electric part remained higher temperature, baking the surrounding cumbustiables, leading to cumbustiable decomposition, carbonization and fire over time.
(2)air conditioner is started immediately after the cessation. Shortly after the air conditioner stops, the pressure difference between inlet and outlet side of compressor is large, the proper step is to not start the air conditioner until the high and low pressure sides reach balance by means of capillary, otherwise, it is likely to increase compressure load and current, leading to motor burndown.
       5、exessively low power supply voltage
Supply voltage of the air conditioners is too low to keep cooling fan motor speed large enought to dissipate heat, as a result, calpboard, gasket,or short-circuit of overheated motor are ignited by high temperature.
二、 Fire prevention measures for air conditioner
       1、 choose quality air conditioner of good brands.
       2、Have professional air conditioner installer to install air conditioners, select wires, plugs and fuses matching the air conditioner
       3、the air conditioner should not be installed too close to curtains, or curtains should be fire-retardant fabrics.

       4、User of air conditioner of electric heating type, when stop heating first cool the electric part with ventilation position, then wait 2 minutes before shutdown.

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