Carbon monoxide is the most harmful toxic gas in the flue gas of fuel. It is inhaled through human respiratory tract, combines with hemoglobin in blood, replaces oxygen and produces carbon monoxide heme, which causes people to die due to hypoxia and asphyxia. The effects of various concentrations of carbon monoxide on the human body are as follows:

Effects of various concentrations of carbon monoxide on the human body

Effects of concentration (PPM) on the human body

100                                Maximum allowable value

200                                Minor headache for 2-3 hours

400                                Headache and nausea for 1-2 hours

800                                45 minutes of convulsions, 2 hours of coma

1600                              20 minutes of convulsions, 2 hours of death

2400                              15 minutes of convulsions, 1 hour of death

3200                               5 minutes of convulsions, half an hour of death

6400                                     Died in 10 minutes

As can be seen from the above table, once the level of carbon monoxide in the air exceeds 800ppm, people will suffer from spasms (i.e., loss of self-control activity ability, inability to prevent further deterioration of the environment, leading to the risk of coma and death). Therefore, for normal people, indoor carbon monoxide concentration of 800ppm is an important threshold value, more than this value, that is, become a toxic environment. And under what conditions can 800ppm be achieved? According to measure, in a volume of 12 m33 (i.e., covers an area of 4 ㎡) close the doors and Windows inside the kitchen, an ordinary eyes stove (refers to the product of flue gas indexes accord with national standard, which converted into carbon monoxide content in flue gas with air coefficient alpha = 1, no greater than 0.05%, the heat load of about 20 mj/h), continuous use within 65 minutes to make fixed carbon monoxide content of 800 PPM, and if in the same room using an old-fashioned, water yield of 5 litres/minute water heater that discharges type continuously is, then only need 11 minutes to achieve this value. This shows that carbon monoxide limits can be easily reached in the case of poor ventilation. In winter, many people close their doors and Windows to bathe, so every year there are reports of deaths from improper use of gas water heaters, and carbon monoxide poisoning is the main cause.

From another point of view, we did another comparative experiment. For a exceeds bid badly give expulsion-typely water heater (more than twice as national standards, the concentration of carbon monoxide in flue gas is the alpha = 1, CO = 0.1%), in a well ventilated room, the room volume was only about 4 m3 (that is, the area of 1.3 ㎡), continuous operation for 1 hour, indoor carbon monoxide content has not been more than 60 PPM, so indoor air environment is safe, completely in indoor sanitation standards. Why have "cause defect" water heater runs for long won't make indoor environment sanitary condition deteriorates, and "qualified" fuel provides the problem that can produce make a person lose one's life in airtight indoor however? This is obviously determined by the key condition of ventilation. Accordingly, the strict stipulation in Japan's gas water heater standard: inside the installation room of straight discharge type water heater, must install ventilation fan, in order to ensure ventilated ventilation. Of course, this is by no means to say that the manufacturing quality of the fuel is irrelevant, but that good ventilation is the decisive condition to ensure the quality of indoor air satellite (even if the quality of the exhaust smoke of the fuel is not up to standard).

General requirements, indoor carbon monoxide content is not more than 24ppm (0.0024%), in order to meet this standard, for the use of fuel in the room, the best way is to strengthen ventilation, but ventilation should be appropriate. If the ventilation volume is too large, it will make the room form a strong air flow, which makes people feel uncomfortable, and may affect the normal combustion of the flame. If in winter, the ventilation rate is too large to reduce the indoor temperature. Ventilation is too large, will also increase the mechanical power consumption and increase the mechanical noise, and will cause new pollution sources. If the ventilation volume is too small, it can not achieve the purpose of ventilation