What is the fire classification for concentrated sulfuric acid?

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Some seniors asked me this question: What fire category does concentrated sulfuric acid fall under? This is a controversial issue, and the analysis below represents only personal opinions. Personally, I don’t think it should be classified as Category B; I classify it as Category D. To answer this question, it is first necessary to clarify a few concepts. First, what is fuming sulfuric acid? And what is concentrated sulfuric acid? Fuming sulfuric acid is sulfuric acid with a concentration of over 100%, meaning it contains free sulfur trioxide gas. When this liquid is in an open state, the sulfur trioxide gas escapes, and due to its strong tendency to combine with moisture in the air, a white acidic mist is formed, giving the impression of smoke; hence the name fuming sulfuric acid. It possesses strong oxidizing properties, as well as water-absorbing, dehydrating, and corrosive properties. Concentrated sulfuric acid generally refers to sulfuric acid with a concentration of over 75%. Second, concentrated sulfuric acid has the property of being difficult to vaporize (it has a high boiling point). Third, there are two forms of corrosion caused by sulfuric acid: one is the dehydrating effect of concentrated sulfuric acid on organic substances; the other is the corrosion of metals and non-metals by sulfuric acid at lower concentrations. High-concentration sulfuric acid, on the other hand, does not have a corrosive effect on metals (high-concentration sulfuric acid can be stored in carbon steel tanks). Fourth, what are the strong oxidizing properties of concentrated sulfuric acid? ① At room temperature, concentrated sulfuric acid can cause metals such as iron and aluminum to become passivated. ②When heated, concentrated sulfuric acid can react with all metals except gold and platinum to form high-valent metal sulfates; it itself is generally reduced to SO2 (note that this occurs when heating). PS: Sulfuric acid is hygroscopic, so a desiccator is necessary. Taking all these points into account, the danger associated with fuming sulfuric acid can be seen from its definition. Regulatory standards classify fuming sulfuric acid as Category B; in my opinion, concentrated sulfuric acid stored in carbon steel tanks equipped with desiccators is stable in nature and does not pose the risks associated with Category B substances. If it were classified as Category B, there would be disputes and safety concerns regarding fire protection design, as sulfuric acid becomes dangerous once it is diluted. According to petrochemical regulations, my current fire protection system is designed for Class D. But the fire separation distance has been artificially exaggerated (o(∩_∩)o...). Discussion is welcome, but there are many definitions of it as Category B online