Regarding Category C substances, does an increase in temperature turn Category B into a source of flammable gas release?
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According to the petrochemical regulations, liquids of Category A that have an operating temperature above their flash point are classified as Category B A liquids. First, it is necessary to determine whether the explosion limit is affected by temperature; from the information I have found, the explosion limit is determined under normal temperature and pressure. For example, ethylene glycol, which belongs to Category A liquids, has a flash point of 116 degrees, and its explosion limit ranges from 32% to 63% – a quite narrow range. So the question is: if the operating temperature of ethylene glycol exceeds its flash point, will its explosive limit range change? Even some Class C solids at room temperature, for which no explosion limit can be determined at all, can be upgraded in classification. 2. Secondly, how to meet the flammable gas conditions? According to GB 50493, the set value for the first-level alarm of flammable gases should be less than or equal to 25% LEL; however, if the explosion limit of ethylene glycol is used, this alarm value would be very high, far exceeding the actual value appropriate for alarm setting based on the explosion limit. How to solve it?
1. Indeed, an increase in temperature affects the volatility of substances, increasing the release of gases or vapors and leading to changes in the explosion limit range. For ethylene glycol, when the operating temperature exceeds its flash point, it can release more vapor; therefore, its explosive limit may change in high-temperature environments. Especially in enclosed spaces, this change may be more noticeable. 2. The alarm setpoints for flammable gases should be adjusted according to the actual environment and the properties of the substances. If the operating temperature of ethylene glycol exceeds its flash point, increasing its volatility, the alarm threshold should be reduced accordingly to ensure safety. Depending on the specific operating environment and properties of the materials, the explosion limits at different temperatures can be determined through experiments, and appropriate alarm thresholds can be set accordingly. This may require collaboration with security equipment manufacturers or professional security consultants to ensure the accuracy and effectiveness of the alarm system. .