What is the "small breathing" loss of oil storage tank

When the oil in the oil storage tank is still stored without receiving and sending operation, the gas space temperature, oil evaporation rate, oil vapor depth and vapor pressure in the tank also change with the rise and fall cycle of external temperature and pressure in one day. The oil loss caused by the process of discharging oil vapor and inhaling air gas is called "small breathing" loss, It is also called static storage loss of oil storage tank.

The main cause of "small breathing" loss of oil storage tank is the change of atmospheric temperature. When the temperature rises with the increase of solar radiation from dawn, the temperature of oil in the tank also changes, causing the evaporation speed to accelerate and the evaporation pressure to increase. When the pressure exceeds the positive pressure rating of the breathing valve, the oil-gas mixture in the tank is discharged into the atmosphere through the breathing valve, which is the "exhalation" process of the oil storage tank. When the sunlight gradually weakened, the temperature of oil in the tank also decreased, the evaporation rate gradually slowed down, and the pressure in the tank also decreased. When the pressure in the tank is lower than the negative pressure rating specified by the breathing valve, the outside air is sucked into the tank through the opened vacuum valve, which is the "suction" process of the oil storage tank.