On the toxicity classification of dichloromethane
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The new version of GB20801 classifies pressure pipelines based on their acute toxicity levels; the classification for acute toxicity is determined in accordance with GB30000. For details, see the attached diagram. After consulting various manuals and online resources, the LD50 and LC50 values for dichloromethane are as follows: the LD50 is between 1600 and 2000 mg/kg, which indicates a low level of toxicity, while the LC50 is 88,000 mg/m3. GB30000 uses mL/L as the unit of measurement. Given that the relative density of dichloromethane gas is 2.93 (with air having a density of 1), the density of dichloromethane gas is approximately 3.78 kg/m3. Using this value, the units are converted to mL/L. In summary, the acute toxicity category is not high; however, according to HG20660, dichloromethane is classified as highly hazardous. Therefore, it is unclear which classification should be applied to dichloromethane in terms of pressure pipelines. As an aside, HG20660 classifies sulfuric acid as extremely hazardous...
According to GSH, dichloromethane is classified as Category 4 for acute toxicity – oral; it also falls under other hazard categories such as Category 2A for severe eye damage/eye irritation
I have a question: should dichloromethane in atmospheric-pressure storage tanks also be classified as a highly hazardous substance? Paragraph 6.2.3 of the Detailed Code states that storage tanks for liquids with extremely high and high toxicity levels should not be located within the same fire dike as storage tanks for other flammable and combustible liquids