Classification of flammable and combustible liquids

1. Flammable media refer to gases whose lower explosive limit when mixed with air is <10% or whose difference between the upper and lower explosive limits is ≥20%, as well as liquids with a flash point ≤45%. 2. Generally, they are classified into four grades and two categories: Grade 1 has a flash point of 45°C to ≤120°C; Grade 4 has a flash point >120°C. Liquids in Grades 1 and 2 are referred to as flammable liquids ； Liquids of grades 3 and 4 are referred to as flammable liquids. 3. The classification of the toxicity level of chemical media and the flammability of such media in pressure vessels is based on the provisions of HG20660 \"Classification of Toxicity Hazards and Explosion Risks of Chemical Media in Pressure Vessels\". When no specific provisions are given, the degree of toxicity is determined according to the following principles: 1. Extremely hazardous (Grade I): The maximum allowable concentration is <0.1 mg/m³ ； 2. Highly hazardous (Class II): Maximum allowable concentration of 0.1–<1.0 mg/m³ ； 3. Moderate hazard (Grade III): Maximum allowable concentration of 1.0–<10 mg/m³ ； 4. Mild hazard (Grade IV): The maximum allowable concentration is ≥10 mg/m³. (II) When the medium in a pressure vessel is a mixture, the toxicity level of the medium or information indicating whether it is a flammable medium shall be provided by the process design team of the design unit, or by the production technology department of the operating unit, based on the components of the medium and in accordance with the aforementioned criteria for toxicity or flammability. If such information cannot be provided, the determination shall be made based on the medium with the highest level of toxic hazard or explosion risk.

Question: Where can I find the original sources for the data and classification criteria mentioned above?

HG20660 \"Classification of Toxicity Hazards and Explosion Risks of Chemical Media in Pressure Vessels\"

GB30000.7 and GB50160

I would like to ask if there are specific classifications for combustible liquids and flammable liquids? I see that the Petrochemical Regulations and GB30000 classify flammable liquids and highly flammable liquids separately, yet the criteria or boundaries used for such classification actually overlap; in other words, there is no clear distinction between flammable and highly flammable liquids. However, it seems that management has certain requirements regarding the classification of highly flammable and flammable liquids.

The classification of media as “flammable” in the Catalogue of Special Equipment is determined in accordance with GB 50160; it represents a assessment from the perspective of fire hazard in firefighting. “\"Flammability\" is determined in accordance with the provisions of GB/T 42594 \"Guidelines for the Classification of Hazards of Media in Pressure Equipment\".