Cryogenic Tank Boil-Off Rate (BOR) Calculator

Calculate daily boil-off rate (BOR %/day), boil-off gas mass (BOG), insulation heat ingress, and safe hold time for cryogenic storage tanks per CGA / NFPA 59A.

Tank Geometry & Cryogen

Gross Tank Volume (m³):

Cryogenic Fluid:

Tank Fill Level (%): Max allowable liquid filling per CGA

Total Heat Ingress Q_in (Watts): From perlite/vacuum & piping support heat leak

Boil-Off Gas (BOG) Metrics

Boil-Off Rate (%/day):

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Daily Mass Boil-Off (kg/day):

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Daily Vapor Generation (Nm³/day):

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Initial Stored Cryogen Mass:

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Mass Evaporation Rate:

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Frequently Asked Questions

What is a typical Boil-Off Rate (BOR) for commercial cryogenic tanks?

High-vacuum multi-layer insulated (MLI) transport tanks achieve 0.1% to 0.3% per day. Large stationary LNG storage tanks (100,000+ m³) typically achieve 0.05% to 0.10% per day.

Why is Liquid Hydrogen (LH₂) boil-off substantially more difficult to manage?

Hydrogen has an exceptionally low boiling point (20.3K) and tiny latent heat per unit volume (~31.5 MJ/m³ vs ~160 MJ/m³ for LN₂), making it ultra-sensitive to minor thermal bridging.

How does ullage space affect safe hold time before venting?

As heat enters a sealed cryogenic vessel, a portion of the boil-off gas compresses into the vapor ullage space, raising tank pressure. When pressure reaches safety relief setpoint, the valve cracks open.