Issues with the oxygen content measurement values in oxidation reactions involving high-risk processes
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It is well known that for high-risk processes such as oxidation reactions, oxygen concentration monitoring instruments are necessary, but what exactly is the threshold value at which an alarm should be triggered? Do I need to calculate it? Is there any simple way? There is a facility that sets off an alarm when the oxygen level exceeds 18%, which seems unreasonable. Can any experts in this field discuss it?
It is a problem related to a combustion zone with upper and lower limits; common substances can be estimated using manuals, with an additional safety factor added. It is a non-common substance; testing by a professional company is required.
I think first: we can discuss this with the manufacturers who have set 18% – they are likely to be better aware of the basis for that value. Second: as mentioned above, we should hire a professional company to assess how it should be set； Third: The oxygen alarm thresholds vary depending on the industry. In our company’s coal grinding system, the normal oxygen level is maintained between 5-6%; an alarm is triggered when this level exceeds 8%. Therefore, the appropriate threshold depends on the specific requirements of the process
I don’t know much about this industry. However, the oxygen content in the air is about 20.9%; to determine whether the external oxygen level is normal, it should not exceed this value.
It is recommended to refer to Appendix A of the standard GB/T 37241-2018 \"Guidelines for Inerting for Explosion Prevention\", which lists the Limit Oxygen Concentration (LOC) values for common flammable gases and flammable dusts. The listed Limit Oxygen Concentration (LOC) values for flammable gases are approximately 2 V% lower compared to sources such as the Perry Handbook; for a few substances like butylene, these values are 1.5–1.8 V% lower, which can be considered as providing a certain safety margin. In practical engineering applications, it is necessary to ensure that the oxygen concentration under the most unfavorable conditions during processes such as oxidation reactions is below this LOC value; in other words, it should be even lower than this LOC value under normal operating conditions. Thus, a safety margin for the oxygen concentration should be established by increasing the 2 V% value further.
This post was last edited by qugd on 2023-2-12 at 10:12. In the process packages for oxidation reactions, especially those high-risk oxidation reactions you mentioned, specific requirements regarding the oxygen content in the reaction system are established. These requirements are determined based on the composition of the reaction medium, the operating temperature and pressure, as well as the nature of the reaction changes. The data provided in the process packages serve as the main reference, while relevant standards constitute the principles guiding the design. As for the 18% oxygen level mentioned by the original poster as the alarm threshold, have you mixed up the low-oxygen alarm value for confined spaces with the upper limit for oxygen content in the mixture used in chemical process reactions? The oxygen content in normal air is about 21%; levels below 18% result in a low-oxygen environment that can cause discomfort. If that’s indeed the case, it is recommended that you leave your current job and thoroughly learn some safety knowledge related to chemical processing before taking on such work.
Specifically, it is also necessary to consider the explosion lower and upper limits of various materials in your reaction system
That makes sense; we can’t mix up the concepts.