What is Flash Point?

The flash point is also called the flash point. It is the lowest temperature at which a flash fire occurs when the fuel mixes with the outside air and comes into contact with the flame. It indicates the tendency of the oil to evaporate and the stability after heating. It is an important indicator of safety protection in fuel storage, transportation and use. Fuels with a high flash point are not likely to cause a fire, and fuels with a low flash point should be stored safely during transportation. ^[1]

Flash point is also called flash point. The temperature at which the oil is heated under specified conditions to the point at which a flash fire is caused by the flame. The flash point of the oil is mainly related to its evaporation; the lighter the fraction, the easier it is to evaporate, and the lower the flash point. The lower the flash point of the oil, the more likely it is to be ignited by a flame to cause combustion, and the greater the danger of fire. Therefore, the flash point can be regarded as a fire safety indicator. Whether liquids are flammable or combustible is grouped according to their flash points. Measure the flash point of heavy oil such as lubricating oil. If it is found that the flash point drops sharply, it can be judged that it is mixed with light fuel oil. The bitumen is heated in the prescribed flash point to the lowest temperature at which an instant flash fire occurs. The most commonly used Blinken opener flash points, Cleveland opener flash points, and Panma's closed cup flasher points are used. China's current standard uses the Blinken open cup flash point. From a fire protection standpoint, the flash point of a liquid is the lowest temperature at which a fire can occur. The lower the flash point, the greater the risk of fire.

Slowly heat the substance to a certain temperature. If a flame appears, it flashes and burns, but it extinguishes instantly. This temperature is called the flash point. However, if the temperature continues to rise, the volatile components that occur will be sufficient to continue. Maintaining combustion without the flame extinguishing, the lowest temperature at this time is called the physical

(1) Tag Closed Cup, referred to as TCC. Applicable to substances with a flash point below 80 degrees.

(2) The Pensky-Martens closed cup method is a method for determining a higher flash point. , Referred to as PM method.

The flash point is measured in a flash point measuring instrument. Depending on the test instrument, the split cup test flash point (Open cup) is indicated by OC, and the closed cup test flash point (Closed cup) is indicated by CC. The former is measured by heating the flammable liquid in an open container; the latter is measured by heating the flammable liquid in a specific closed container. The flash point of a closed cup test is generally It is 4 to 5 ° C lower than the flash point of the open cup test. The standards of the instruments used in different countries are different. The test instruments used in Britain and the United States include Peusky-Martens (closed cup test) and Cleveland (open cup test). These two instruments are Standard equipment recommended in International Maritime Danger Regulations.

Generally the flash point of flammable liquids can be divided into 3 categories according to the temperature: (1) low flash point liquid, that is, the closed cup test flash point is lower than -18 ° C; (2) medium flash point liquid, the closed cup test flash point -18 23 ; (3) High flash point liquid, the flash point of closed cup test is 23 61 . Closed cup test flash point above 61 , said flammable liquid. For example, the flash point of gasoline is -45 ° C, which is a low flash point liquid; the flash point of alcohol is 14 ° C, which is a medium flash point liquid. ^[2]

The height of the flash point depends on the density of the flammable liquid, the pressure of the liquid surface, or whether the light components and the content of the light components are mixed in the flammable liquid. If the flash point of a flammable liquid is suddenly lowered during use, light oil mixed accidents or hydrolysis (for some synthetic oils) may occur, which must be paid attention to.

The flash point of a flammable liquid varies with its concentration. The height of the flash point is related to the molecular composition of the oil and the pressure on the oil surface. The pressure is high and the flash point is high.

Flash point is an important indicator to prevent oil fires. In open containers, the heating temperature of the oil should be 10 ° C below the flash point; there is no such limitation for heating in pressure vessels.

From the perspective of fire prevention, it is desirable that the flash point and ignition point of the oil are higher, and the difference between the two is larger. From the perspective of combustion, it is desirable that the flash point and the ignition point be lower, and the difference between the two should be as small as possible.