Qualitative analysis of ammonia water: New problems for veteran revolutionaries
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Upon checking the design documents, 20% ammonia water is classified as Category B of Ethyl B; the reason given is that it was determined during the preliminary evaluation. Later, I checked with the client in another project; the preliminary evaluation identified option B, but no detailed reasons were given over the phone. Now this is troublesome. Have you encountered this situation before? How was it handled?
Those below 8% do not need to be classified as Category B, while those equal to or above 8% are classified as Category B
According to the List of Dangerous Goods Names (GB 12268-2012), it seems that only ammonia solutions with an ammonia content of over 50% are classified as Category B; all others are not: UN number: 1005. Anhydrous ammonia. UN number: 3318. An ammonia solution, an aqueous solution with a relative density of less than 0.800 at 15°C and an ammonia content of over 50%. The hazards of the two are essentially the same; category or class: 2.3 (toxic gas). Secondary hazard: 8 (corrosive substance). Special provision: 23 (Even though this substance poses a flammability hazard, such hazard only manifests itself when there is intense burning within a confined space). UN number: 2073. An ammonia solution, an aqueous solution with a relative density of less than 0.800 at 15°C, containing not less than 35% but not more than 50% ammonia. Category or type: 2.2 (non-flammable, non-toxic gas). UN number: 2672. Ammonia solutions, aqueous solutions, have a relative density of 0.800 to 0.975 at 15°C, with an ammonia content of not less than 10% but not exceeding 35%. Category or type: 8. Packaging category: III.
\"Code for Design of Urban Gas\" (GB 50028-2006): Appendix B, Table B-2, Classification of explosion and fire hazard zones in main production areas; pump rooms for concentrated ammonia water (≥8%), and outdoor areas of concentrated ammonia water production facilities are classified as Zone 2. The terminology used here is essentially the same as that for anhydrous ammonia (liquid ammonia). Zone 2 is defined in GB50058-2014, the Code for Design of Electrical Installations in Explosive Atmospheres; its main purpose is explosion prevention. There have indeed been cases in China of ammonia tanks exploding when exposed to an open flame. Can this indicate the fire classification of ammonia water? If it’s possible, then why aren’t the relevant safety regulations established?
It is defined in that way; if you disagree, seek expert opinions for verification. For regulatory matters, only the definition that ensures the highest level of safety can be adopted. It is not possible to base things on optimization limits; as long as there is a risk of fire, design must be carried out in strict accordance with fire safety regulations.
Are you asking about the production category of the main manufacturing site? Or the fire hazard zone classification? These are two different concepts.
Ask the entities conducting the preliminary evaluation, hear their opinions; it’s right to follow the strictest standards and to be cautious.
But in the past, it was always done according to Categories D and E.
Ammonia will be released from ammonia solutions with a concentration of less than 10%; when the gas in such storage tanks comes into contact with an ignition source, an explosion can occur. However, solutions with a concentration of less than 10% are not considered hazardous chemicals. It is certainly incorrect to classify ammonia solutions with a concentration of less than 10% as Category B. Therefore, in accordance with the «List of Hazardous Goods» (GB 12268-2012), I recommend classifying solutions with a concentration of 20% or less as Category D or E, while those with a concentration above 20%, due to their high volatility, can be classified as Category B
According to the List of Dangerous Goods Names (GB 12268-2012), the UN number is: 2073. An ammonia solution, an aqueous solution with a relative density of less than 0.800 at 15°C, containing not less than 35% but not more than 50% ammonia. Category or type: 2.2 (non-flammable, non-toxic gas). Can non-flammable and non-toxic gases be classified as Category B?