Issues regarding flash point and explosion limit in GB50058

The flash point applies only to flammable liquid media. For combustible gases, there is only an explosive limit range, and no flash point. Some substances have neither a flash point nor an explosive limit, yet they are still listed in the appendix; I think this is probably because they have exploded in real-world situations.

What you should look at is the pseudo-norm. :Lol, explosiveness is never determined by flash point and explosion limit; those values are used in the Building Code to classify fire hazards. Chemicals are classified in accordance with this standard, GB 30000.2-2013 Standard for the Classification and Labelling of Chemicals – Part 2 **

Flame points exist only for flammable liquids; for flammable gases, there is only an explosive range.

My description is incomplete; let’s set a range: liquids. Liquids have no flash point but do have an explosive limit, such as dichloromethane

Of course I know this common sense. What I discussed in my post is liquids. :lol

Can we discuss explosion issues in building codes? GB50058 is specifically about environments with explosion hazards. Feel free to continue the discussion.

The logic is reversed. The explosive hazardous environments defined in GB50058 are divided into explosive gas environments and explosive dust environments. An explosive gas environment refers to situations involving combustible gases, combustible liquids with a flash point lower than the ambient temperature, and combustible liquids whose operating temperature is higher than their flash point; electrical equipment must be designed to be explosion-proof in these three scenarios. This merely sets a limit; anything outside this range falls outside the scope of GB50058, except in cases where there is evidence to the contrary.

This post was last edited by arpcd on 2017-3-15 at 19:26. I agree with the opinion of the user from the third floor. Flash point is not an essential criterion for judgment. The original poster is being too rigid in their thinking; one set of regulations cannot cover all explosives. That’s all you need to understand. I give you a lump of C4; you try to light it with fire and you might not even be able to ignite it, but that doesn’t mean the C4 won’t explode. Its explosive power isn’t such that it can explode on its own (a special fuse is required for that) ? Try hitting it hard with a hammer, or use a bullet – nothing explodes, but that doesn’t mean these things aren’t dangerous, right? The United States has an extreme example that illustrates this issue. There was once a liquid intercontinental ballistic missile in the U.S. (launched from a silo); I can’t remember its model. During maintenance work, an accident occurred and liquid fuel leaked out. At that time, rocket fuel consisted of unsymmetrical dimethylhydrazine (the same type of fuel used in China’s Long March series of rockets; kerosene and liquid oxygen are technologies that only emerged later). This led to a fire and explosion, which sent the hydrogen bomb hundreds of meters outside the silo and created a large crater on the ground. The hydrogen bomb itself wasn’t damaged, but everyone was terrified. If that thing had exploded, the entire base would have been destroyed. So why were people so scared? Was it the hydrogen bomb that was dangerous, or the fuel? ? They are all dangerous; it’s just that the danger associated with fuel is easier to see, as it has a flash point and tends to evaporate. But that doesn’t mean you can ignore the danger posed by hydrogen bombs. . . . That’s the reasoning. . . The reason is simple: for dichloromethane, the fact that its flash point isn’t listed doesn’t mean it doesn’t exist; it’s just that due to various constraints, there are no accurate figures available. The people who develop these standards are also human beings, not gods; they can’t collect that many physical property data points, let alone conduct experiments (who would do such pointless experiments anyway?) ), but dichloromethane has a self-ignition point (I think it’s over 600 degrees), as well as upper and lower explosion limits, which is enough to show that it poses an explosion risk – that’s all there is to it.

This post was last edited by arpcd on 2017-3-15 at 19:30. The main point is that if you have time, I suggest you check the explanatory notes of those standards; it’s best to compare them with relevant American standards as well. To be honest, China’s standards are just copies – to use an offensive expression, they even make mistakes when copying. . . Let’s take a look at what is stated in the \"Explanations for the Amendments to the Code for Design of Electrical Installations in Explosive Atmospheres GB50058-2014\": Determining the scope of explosive hazard areas is a rather complex task, and it becomes even more difficult to carry out this process in practice without illustrative examples. To facilitate compliance with the code, some typical examples are provided therein; most of these examples are drawn from API RP505 of the American Petroleum Institute and NFPA 497 standard of the National Fire Protection Association. Due to differences in the processes, equipment, instruments, ventilation, and layout of actual installations, comprehensive consideration of practical conditions and operational experience is required in the specific design, so as to determine whether a larger or smaller distance should be adopted. In many ** and IEC standards, examples of the boundaries of certain hazardous areas are provided in the appendices or diagrams of the standards; this is not a mandatory requirement, but rather serves as guiding examples. Given the specific characteristics of various industries, industry-related **standards** can often be used to determine the scope of hazardous areas. For example, for the design and construction of new, expanded, or renovated automobile gas stations, LPG filling stations, CNG filling stations, and combined gasoline and gas filling stations, the \"Code for Design and Construction of Automobile Gas Stations\" GB50156 should be applied. For the scope of explosive hazard areas in oil and gas fields, their pipeline systems, and oil depots, other standards can be referred to, such as \"Classification of Electrical Installations in Petroleum Facilities\" SY0025 and \"Code for Design of Oil Depots\" GB50074. The elders have already told you that we’re actually just copying the API and NFPA standards – what more is there to say? ?

Thank you to the thread owner **; it allows us to learn knowledge as well as listen to stories. Rich in content, truly moving.