How is concentrated ammonia water distinguished from dilute ammonia water?
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In our coking production process, there is recycled ammonia water with a concentration of 0.4–0.8%, 10% concentrated ammonia produced through ammonia evaporation, 20% concentrated ammonia obtained from ammonia purification using phosphoric acid, 9.5–10.5% dilute ammonia for medical use, 22–25% concentrated ammonia for industrial use, and 25–28% concentrated ammonia for various other applications. Among all these terms, there are areas of overlap and gaps in coverage, which confuses me. What I would like to ask is whether there are any standards such as GB, HG, SH, or medical regulations that can define what constitutes a dilute ammonia solution – that is, what concentration qualifies as dilute ammonia – and what concentration constitutes concentrated ammonia, or whether there are standards related to the pH value for ammonia. Because this is a vague concept in pressure pipelines, I want to understand it better; I hope someone knowledgeable can help. Also, don’t use the institute’s logos or information found on Baidu – those have no validity in the safety inspection process. Thank you!
Anything below the medical concentration is dilute ammonia water.
Do you have any relevant specifications or standards?
1. The ammonia-containing liquids present in the gas purification workshop, such as high-pressure ammonia water, recycled ammonia water, residual ammonia water, ammonia-rich water, semi-ammonia-rich water, ammonia-evaporation wastewater, and gas condensate, have very low concentrations (generally not exceeding 1.0%). 2. After reviewing relevant materials and standards, the parameters for pressure pipelines are specified based on factors such as the toxicity and corrosiveness of the medium, pipeline pressure, and pipe diameter: ① Toxicity: The toxicity of the media listed in Article 2 is considered to pose a mild hazard (according to the classification criteria in GBZ230) ； ② Corrosivity: As defined in Appendix A2.3 of the TSGD0001-2009 Industrial Pipe Code, the corrosion rate of ammonia solutions on carbon steel and cast iron is approximately 1 mm/year or less ； ③ The supplementary material for the training of personnel responsible for the design approval of pressure pipelines in steel systems provides examples of pressure pipeline categories, stating that concentrated ammonia water belongs to GC-class pipelines, but it does not specify the concentration ； Table 2 in Appendix B of the \"Code for Design of Town Gas Systems\" GB50028 specifies that the area of pump rooms handling concentrated ammonia water (≥8%) is classified as Zone 2 in terms of the classification of fire and explosion hazard zones in major production areas ； The GB12268 list of hazardous chemicals specifies that transportation as a hazardous material is only considered when the concentration exceeds 10% ； 3. Conclusion: Through research, it has been determined that the aforementioned pipelines do not belong to pressure pipelines. I asked this question myself and spent several days looking for information, but I couldn’t find that much so far. Friends who have different opinions can help me improve it
Code for Design of Town Gas GB50028