Old K says every week -- Post 52: How to consider the exhaust volume of the breathing valve under fire conditions

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This post was last edited by henglinkou on 2021-6-15 at 17:54. Old K’s weekly series – Talks about things in the petrochemical design industry, Post 52: How to determine the exhaust volume of vent valves under fire conditions. On page 93 of the second volume of the fifth edition of the “Chemical Process Design Handbook,” it is stated as follows: “Although API 2000–2014 (7th edition) allows that for storage tanks with a weak roof design, no additional emergency exhaust volume is required once an adequate exhaust volume for normal operating conditions has been taken into account, this handbook still recommends considering such an additional emergency exhaust volume, in order to ensure the reliability of exhaust function in case of a fire.” If the storage tank is not designed with a weak roof structure, the emergency discharge volume in case of a fire should be calculated using equation (34-21). ”Since the exhaust volume calculated under fire conditions is generally large, if this amount is taken into account for the exhaust flow from the breather valve, the size of such a valve will need to be larger, or an increased number of breather valves will be required to meet the demands; in some cases, it is even difficult to find breather valves of that size. I recommend that for larger storage tanks, pressure relief manholes be used to meet the discharge requirements under fire conditions. I have prepared a vent valve calculation sheet based on the fifth edition of the \"Chemical Process Design Manual,\" which can improve work efficiency and reduce labor intensity as well as errors caused by human factors. For specific details, see the figure below; everyone is welcome to share and discuss. Tip: You can enter “Lao K’s Weekly Updates – Insights into the Petrochemical Design Industry” in the website’s search engine to view previous posts