Cryogenic Boil-Off Rate (BOR) Calculator
Calculate daily evaporation loss percentage (%/day), thermal heat leak wattage (W), and lock-up pressure rise time in vacuum-insulated cryogenic vessels.
Vessel Geometry & Fluid Selection
From dewar vacuum MLI thermal rating
Boil-Off Rate & Venting Timeline
Daily Boil-Off Rate (BOR):
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Daily Liquid Evaporation:
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Venting Gas Volume Flow:
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Lock-Up Pressure Rise Time:
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Total Stored Liquid Mass:
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Insulation Efficiency:
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Cryogenic Storage Boil-Off Rate (BOR) Physics
Cryogenic liquids ($LN_2, LOX, LNG$) boil at atmospheric temperatures far below freezing ($-162^circ ext{C}$ to $-196^circ ext{C}$). Because perfect insulation is physically impossible, radiant, conductive, and convective heat leaks constantly enter the inner container, vaporizing liquid into boil-off gas (BOG).
Boil-Off Mass Evaporation Formula
m_loss = Q_leak / h_fg BOR (%/day) = (m_loss · 86,400 / M_stored) · 100%