How do you read a vacuum insulation specification for a cryogenic storage tank and what do the numbers mean for your LN2 bill?
The static evaporation rate, expressed in litres per day, is the single most important number on a vacuum insulated cryogenic storage tank specification sheet. It tells you how much LN2 the vessel loses per day simply by existing at room temperature with no access events. A vessel rated at 0.08 litres per day will lose approximately 29 litres per year in standby losses alone. A vessel rated at 0.35 litres per day loses over 127 litres per year under identical conditions. At a delivered LN2 price of £0.80 per litre, that difference is £78 per year per vessel in standby losses alone, before a single access event is counted.
The vacuum insulation works by maintaining a near-vacuum between the inner and outer vessel walls, which eliminates convective and conductive heat transfer. The quality and longevity of this vacuum determines how the static evaporation rate changes over the vessel’s operating life. A low-quality vacuum degrades within 2 to 3 years, causing the evaporation rate to climb significantly above the rated figure. The vacuum warranty is therefore a meaningful indicator of build quality. Cryolab’s storage vessel range is supplied with rated static evaporation figures and a 3-year vacuum warranty as standard. When comparing vacuum insulated cryogenic storage tanks from different suppliers, always calculate the 5-year total LN2 cost based on the rated evaporation rate rather than comparing purchase prices in isolation. Contact Cryolab for a full specification comparison across the range.
