Gas Risks

The purpose of this section is to give users of BOC Cryospeed low temperature liquefied gases information on their properties, the hazards associated with their use and simple precautions to be taken to ensure they are used safely. Detailed safety information for individual gases is provided in BOC safety data sheets

Properties of low temperature liquefied atmospheric gases

The hazards associated with the low temperature liquefied gases relate to their physical properties. Some physical properties of the five liquefied atmospheric gases are given in the table below. All five gases are odourless and non-flammable in air. Carbon dioxide has a distinctive taste in high concentrations ( 10%) but the others are tasteless.

Property	Oxygen (O2)	Nitrogen (N2)	Argon (Ar)	Carbon Dioxide (CO2)
Molecular weight	32	28	40	44
Colour of gas	None	None	None	None
Colour of liquid	Light Blue	None	None	None
Normal boiling point at atmospheric pressure(°C)	-183	-196	-186	-78.5
Ratio of volume gas to volume of liquid, measured at 15°C and absolute pressure of 101.3kPa	842	682	822	845 (solid)
Relative density of gas at 101.3 kPa (Air = 1)	1.105 @25oC	0.967 @25oC	1.380 @0oC
Liquid density at absolute pressure of 101.3 kPa (kg/m3)	1141	807	1395	190
Latent heat of evaporation (kj/kg)	213	199	161	573 (sublimation)

Hazards

The hazards arising from low temperature liquefied gases are:

Cold burns, frostbite and hypohthermia from the cryogenics properties.
Asphyxiation in oxygen deficient atmospheres.
Fire in oxygen enriched atmospheres.
Overpressurisation from the large volume expansion of liquid

Please Note:

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