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Liquid hydrogen
Hydrogen is colorless as a liquid. Its vapors are colorless, odorless,
tasteless, and highly flammable. Liquid hydrogen is non-corrosive.
Special materials of construction are not required to prevent
corrosion. However, because of its extremely cold temperature,
equipment must be designed and manufactured of material, which is
suitable for extremely low temperature operation. Vessels and piping
should be designed to the American Society of Mechanical Engineers (ASME)
Code and the American National Standards Institute (ANSI) Pressure
Piping Code or Department of Transportation (DOT) Codes for the
pressure and temperatures involved.
Physical Properties
• Molecular Weight: 2.016
• Boiling Point @ 1 atm: -423.0°F (-252.8°C, 20oK)
• Freezing Point @ 1 atm: -434.5°F (-259.2°C, 14oK)
• Critical Temperature: -399.8°F (-239.9°C)
• Critical Pressure: 188 psia (12.9 atm)
• Density, Liquid @ B.P., 1 atm: 4.23 lb./cu.ft.
• Density, Gas @ 68°F (20°C), 1 atm: 0.005229 lb./cu.ft.
• Specific Gravity, Gas (Air = 1) @ 68°F (20°C), 1 atm: 0.0696
• Specific Gravity, Liquid @ B.P., 1 atm: 0.0710
• Specific Volume @ 68°F (20°C), 1 atm: 192 cu. ft./lb.
• Latent Heat of Vaporization: 389 Btu/lb. mole
• Flammable Limits @ 1 atm in air 4.00%: -74.2% (by Volume)
• Flammable Limits @ 1 atm in oxygen 4.65%: -93.9% (by Volume)
• Detonable Limits @ 1 atm in air 18.2%: -58.9% (by Volume)
• Detonable Limits @ 1 atm in oxygen 15%: -90% (by Volume)
• Autoignition Temperature @ 1 atm: 1060°F (571°C)
• Expansion Ratio, Liquid to Gas, B.P. to 68°F (20°C): 1 to 848
Additional tables
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