Design options for enclosed loading and unloading vehicles
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Section 6.4.2 of GB50160-2008 \"Code for Fire Protection Design of Petrochemical Enterprises\" stipulates that automobile loading and unloading stations for flammable liquids shall comply with the following requirements: 6. For the loading and unloading of Class A B, Class B, and Class C A liquids, submersible loading and unloading nozzles shall be used； We all designed it following this approach, with two options: top-mounted and bottom-mounted. Currently, environmental protection authorities require closed-loading and unloading systems, and HG/T 21608-2012 \"Technical Requirements for Liquid Loading and Unloading Arms\" also sets requirements for such closed systems. In a recent project, Class A B, Class B, and Class C liquids were transferred using submersible loading/unloading nozzles, but the requirements for sealed transfer were not met. Is it necessary to make corrections?
I don’t understand the original poster’s question – in which step is there inadequate sealing during loading?
Looking at the picture, there is a vapor equilibrium tube, and the flexible hoses and tank trucks are also connected via flanges. So as long as the vapor equilibrium tube is connected to the storage tank, isn’t it a closed system?
The environmental requirement for closed-unloading is not based on the aforementioned standards; rather, environmental protection aims to reduce uncontrolled emissions. If the top part in the diagram is a vapor equilibrium hose, then the requirements should be met. If there is no gas-phase equilibrium tube nor a gas-phase collection pipeline, it needs to be rectified. Because even after the exhaust vents are opened, unorganized emissions still occur before and after loading.