Breathing valve and arrester are the key equipment to protect oil tank from lightning. It can be seen from the investigation that many accidents of lightning strike in oil tank are caused by the lack of installation of breathing valve and arrester. At present, most of the gathering and transportation stations, combined stations and meters and transfer stations are equipped with "one valve and one device" at the outlet of crude oil storage tank, that is, the root of breathing valve is equipped with a fire arrester. In the cold areas of the north, most of the cans are equipped with "two valves and one device", and hydraulic breathing valves, also known as hydraulic safety valves, are added to prevent the failure of mechanical breathing valves due to factors such as hanging dew, frosting and freezing cards.
The Historical Origin of Fire arrester
A arrester is a safety device used to prevent the flame spread of flammable gases and flammable liquid vapours. In theory, the fire at the tank vents needs to occur at the same time, that is, there is a fire source near the vents, and the vents produce flammable oil vapor mixture accumulation. For the tank, the flammable mixture discharged from the vents is exposed to open fire from the outside, and the role of the arrester is particularly important when the lightning or static ignition is ignited to the explosion or spread.
The application of arrester in the vents of oil and gas storage tanks originated from the generation of steel storage tanks and the use of exhaust valves in oil and gas storage tanks. In the early stage of oil industry, wooden top covers were used in storage tanks made of wood or forged iron. The permeability and flammability of wooden top covers caused lightning or other ignition sources to ignite the tank fire, which led to the application of riveted steel top cover storage tanks, and the sealing of riveted steel top cover storage tanks triggered the need for controlled ventilation of storage tanks. When the internal pressure of the tank is within a limited range, the valve remains closed, and when the pressure or vacuum exceeds the limited range, the valve can be opened in time to prevent tank damage and reduce fire loss. This valve, which began to be called a breathing valve, is now commonly known as a pressure limiting valve or a pressure vacuum valve, (pv).. As a safety device to prevent the flame spread of flammable gas and flammable liquid vapor, the arrester is installed at the bottom of the tank exhaust valve.
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