The bacteria in central air conditioner exceed the standard seriously

Because central air conditioning dominates the metabolism of air in modern buildings, it is vividly called "lung" of modern buildings. Lung leaves are delicate and easy to be invaded by evil, so it is also called "delicate organs". In the same way, central air conditioning is also easy to be invaded by dirt and bacteria. Due to the long-term operation of the central air-conditioning unit, the ventilation system is easy to be polluted, and the cleaning is not timely, so that a large number of dust and gravel, carbonaceous substances and crystals are left in the pipeline. Once the dust contains bacteria, fungi, yeast and other microorganisms, it is easy to cause allergy or respiratory diseases.

From 2003 to the end of 2005, Beijing Municipal Center for Disease Control and Prevention (CDC) conducted sampling inspection on central air-conditioning in public places in four stages. The results showed that more than 90% of the inspected sites were moderately polluted. Coincidentally, Shandong Provincial Health Supervision Institute and provincial CDC also conducted sampling inspection on Central air conditioning and ventilation systems of 30 public places in Jinan, Zibo and Tai'an. The results showed that 9 of them were moderately polluted and 21 were seriously polluted; the bacteria of central air-conditioning in one shopping mall exceeded the standard by 190 times.

Dust accumulation in air duct is easy to spread pathogens

Common central air conditioning is mainly composed of air handling device and hot and cold air supply pipe. The air treatment device is responsible for the cold and heat treatment of the air, and the treated air is sent to each room through the air duct. Because the humidity of the four walls of the air duct is relatively high, the particles in the air are easy to adhere here and form a thick dust accumulation over time. These dust deposits become a paradise for bacteria breeding, because there are nutrients, suitable temperature and humidity for their survival, and the bacteria will be happy to live, reproduce and spread here.

According to the World Health Organization statistics, the disease burden caused by indoor air pollution is more than five times that caused by outdoor air pollution. Data from scientific research also support this argument. European and American institutions have conducted a lot of research on indoor air pollution caused by central air conditioning system. The results show that 42% of the air pollution in the environment with central air conditioning comes from it, accounting for the largest proportion of all pollution sources. In 2006, China's Ministry of health on the national central air conditioning sampling results also confirmed this problem. The results showed that the hygienic quality of the air supplied by the air conditioner was the most serious. The total number of bacteria exceeded the national average by 36.9%, and the inhalable particulate matter exceeded the standard by 29.6%.

Cleaning the central air conditioner is beneficial to energy saving

According to the investigation, according to the international practice, the central air-conditioning must be cleaned and maintained scientifically once a year, otherwise there will be biological slime blockage, which will affect the cooling effect of central air conditioning, waste energy and increase maintenance costs. According to the data provided by Japan's Kuroda water treatment company, the heat exchange efficiency is reduced by 33% and the energy consumption of central air conditioning is increased by 20% on average due to the fouling thickness of 0.2-0.5mm.

Chen Liqing, a senior engineer who has been engaged in the design and manufacture of central air conditioning and is now engaged in the cleaning work of central air conditioning, said that at present, the equipment cost of cleaning central air conditioning duct is high, resulting in high cleaning cost, which is the main reason that many building properties can not clean the central air conditioning duct system in time. At present, the cleaning price of central air conditioning duct system in commercial buildings in big cities is about 30 yuan per square meter. In other words, it costs tens of thousands to hundreds of thousands of yuan to clean the entire air conditioning system and air supply and exhaust pipes of an office building, which makes many building properties flinch.

But in fact, if the central air conditioner is cleaned regularly every year, the air duct cleaning of the central air conditioner does not need to use that kind of expensive cleaning equipment. Because central air conditioning is in operation, there are three parts: air inlet, air outlet and air duct. If the air inlet and main engine are cleaned every year, the cost of cleaning is not high. The electricity cost saved in a summer is enough. And the air inlet and air duct pollution source solved, its extension to each room of the air supply duct pollution, very little. For example, Changzhou City, a five-star hotel, since the start of the central air conditioning, annual periodic cleaning. The quality indexes of air-conditioning in the hotel (i.e. temperature, humidity, dust, fungi, etc.) are all good after repeated tests by the health department.

Thus, another function of cleaning central air conditioning is to save energy. According to Chen Liqing, a foreign-funded enterprise in Changzhou has a set of central air-conditioning units with a capacity of 500000 kcal. After cleaning the central air-conditioning equipment on a regular basis, it can save about 64000-192000 kwh per year in terms of electricity consumption. According to 0.8 yuan per kilowatt hour (industrial electricity), the annual electricity cost saved is 51200-153600 yuan. And the annual cleaning cost of central air conditioning is only several thousand yuan.