Question about vapor pressure
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An open gasoline storage tank with air above it; assuming that initially there is no gasoline in the gas phase of the tank, the pressure above it is the atmospheric pressure. If the storage tank is sealed at this point, will the pressure inside the tank increase? Eventually, the total pressure will equal the atmospheric pressure plus the vapor pressure at that temperature.
An open gasoline storage tank with air above it; assuming that initially there is no gasoline in the gas phase of the tank, the pressure above it is the atmospheric pressure. If the storage tank is sealed at this time, the pressure will increase after oil is introduced, mainly due to the reduction in the volume of air, which leads to an increase in pressure.
An open gasoline storage tank with air above it; assuming that initially there is no gasoline in the gas phase of the tank, the pressure above it is the atmospheric pressure. If the storage tank is sealed at this point, will the pressure inside the tank increase? Eventually, the total pressure will equal the atmospheric pressure plus the vapor pressure at that temperature. ——No, gasoline has its own requirements regarding saturated vapor pressure, which is not very high – it’s only in the range of a few dozen kilopascals. However, if the air is trapped inside the storage tank, it belongs to the category of non-condensable gases. The pressure in this final storage tank will continue to rise as the gas phase volume decreases. The extent of this increase is not related to the saturated vapor pressure of gasoline, but rather to the degree to which the air inside is compressed. ——This is a mistaken idea; so-called gasoline storage tanks should be large atmospheric-pressure tanks, whose pressure resistance capacity corresponds to the saturated vapor pressure of gasoline, with perhaps a slight margin, and a large amount of non-condensable gas is not allowed to be present.
At normal pressure, the pressure resistance of storage tanks is less than 2000 pascals; if you are in Africa or Hainan Island, overpressure will definitely occur, but this is not the case in most areas. Moreover, it depends on whether you seal the tank in the morning or at noon.
Aren’t all gasoline tanks floating roof tanks?
A gasoline tank is generally a sealed container equipped with a vent valve; if the vent valve is closed, the air inside will be compressed, and problems will arise sooner or later.