 For example, the expansion ratio of cryogenic argon from the boiling point to ambient is 1 to 847, liquid hydrogen 1 to 851, liquid helium 1 to 757, liquid nitrogen 1 to 696, and liquid oxygen 1 to 860; Neon has the highest expansion ratio with 1 to 1438.In dewars with an open top, the gas simply escapes into the surrounding area.However, very high pressures can build up inside sealed dewars, and precautions are taken to minimise the risk of explosion.