Flammable liquid properties

1 . Highly flammable

The main characteristic of flammable liquids is their high flammability, which is mainly due to:

First, almost all flammable liquids are organic compounds. The molecular composition mainly contains carbon atoms and hydrogen atoms, which are easily reacted with oxygen to burn.

Second, since the flash point of the flammable liquid is low, the ignition point is also low (the ignition point is generally about 1 to 5 ° C higher than the flash point), so the flammable liquid is easily ignited by the fire source and continues to burn.

2 . Explosive

The flammable liquid is highly volatile. When the container containing the flammable liquid is damaged or unsealed, the flammable vapor volatilized diffuses to the entire space of the warehouse or the car box where the article is stored or carried, mixed with the air. When the concentration reaches a certain range, that is, when the explosion limit is reached, an explosion may occur when exposed to an open flame or a spark.

When a flammable and combustible gas, liquid vapor, solid dust is mixed with air, the concentration range in which the fire source can cause a combustion explosion is called the explosion limit, and is generally expressed by the volume percentage (%) of the gas or vapor in the mixed gas. The explosion limit of dust is expressed in mg/m3. The lowest concentration that can cause a combustion explosion is called the lower explosion limit. The highest concentration that can cause a combustion explosion is called the upper explosion limit. When the concentration of the flammable gas or flammable liquid in the air is less than the lower explosion limit, since the amount of combustibles is insufficient and contains more air, the combustion will not occur and will not explode; when the concentration is greater than the upper limit of the explosion, then Due to insufficient air, combustion cannot occur and will not explode. Only in the upper and lower concentration range will it explode if it encounters a fire. Therefore, the greater the range of explosion limits, the lower the lower explosion limit, the greater the risk.

3 . Highly mobile diffusivity

The molecules of flammable liquids are mostly non-polar molecules, and the viscosity is generally small. Not only is it very easy to flow, but also due to penetration, infiltration and capillary phenomenon. Even if the container has only very fine cracks, flammable liquid will seep out of the container. Outside the wall, the surface area is enlarged and volatilized continuously, increasing the concentration of flammable liquid vapor in the air, thereby increasing the risk of combustion explosion.

4 . Heat expansion

The flammable liquid has a relatively large expansion coefficient, and the volume is easily expanded after being heated, and the vapor pressure thereof is also increased, so that the internal pressure in the sealed container is increased, causing a "drum" or even a burst, which may occur when the container bursts. The spark caused a burning explosion. Therefore, the flammable liquid should be stored away from heat, and there should be more than 5% of the gap in the container during filling, and it should not be filled.

5 . Avoid oxidants and acids

When a flammable liquid comes into contact with an oxidizing agent or an oxidizing acid (especially nitric acid), it can react violently to cause a combustion explosion. This is because flammable liquids are organic compounds that oxidize with oxidants and generate a large amount of heat, causing the temperature to rise to the ignition point causing a combustion explosion. For example, ethanol will burn when it is contacted with oxidant potassium permanganate. It will also burn when it comes into contact with oxidizing acid-nitric acid. The turpentine will burn immediately with nitric acid. Therefore, flammable liquids must not come into contact with oxidizing agents and oxidizing acids.

6 . toxicity

Most flammable liquids and their vapors have varying degrees of toxicity, such as methanol, benzene, carbon disulfide, and the like. Not only does it inhale its vapor, it can be poisoned, and some can cause poisoning accidents through skin absorption. Should pay attention to labor protection.

(From: China Railways website)