Vented Vapor Saturation Factor formula |
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| \( K_s \;=\; \dfrac{ 1 }{ 1 + 0.053 \cdot P_v \cdot H_{vo} } \) | ||
| Symbol | English | Metric |
| \( K_s \) = Vented Vapor Saturation Factor | \(dimensionless\) | - |
| \( P_v \) = Vapor Pressure at Average Daily Liquid Surface Temperature (psi) | \(lbf \;/\; in^2\) | - |
| \( H_{vo} \) = Vapor Space Outage | \(ft\) | - |
Vented vapor saturation factor, abbreviated as VVSF or \(K_s\), a dimensionless number, for a fixed roof tank is used in the estimation of evaporative losses from liquid storage tanks, particularly those containing volatile organic compounds (VOCs) or hydrocarbons. It quantifies the degree to which the vapor space above the liquid in the tank is saturated with the vapor of the stored liquid. The VVSF is influenced by factors such as the tank's design, the properties of the stored liquid, and environmental conditions like temperature and pressure . It is typically used in emission estimation models to calculate the amount of vapor emitted from the tank through vents due to breathing losses caused by constant temperature changes or working losses caused by filling or emptying the tank. A higher VVSF indicates a greater tendency for the vapor space to be saturated, leading to increased emissions, while a lower VVSF suggests less saturation and reduced emissions. The factor is critical for accurately assessing and managing air emissions from storage tanks in industries like petroleum refining or chemical manufacturing.
