GHS Classification Guidance for the Japanese Government

B) Classification based on data from prescribed literatures
In GHS classes of gas, “gases under pressure” are conditions made in the pressure vessels by
manufacturers depending on their purposes such as transport and use. And other properties
(flammable gases, oxidizing gases, acute inhalation toxicity)are based on hazards when these
gases exist in air at a standard pressure.
In the new GHS classification, “gases under pressure” are categorized into individual groups
depending on critical temperatures obtained, in principle, from prescribed review documents
and conditions assumed during transport.
If the gas under pressure is a single substance, categories of refrigerated liquefied gas and
dissolved gas are not applied.
(4)Data availability
The data required are vapor pressure at 50 °C physical properties at 20 °C and atmospheric
pressure, and critical temperature (GHS2.5.4.2). All of them can be obtained relatively easily.
Physical conditions, pressure, and the like, when compressed in cylinders, depend on the design of
manufacturers.
(5)Comparison with conventional classification systems
The definition of Class 2 (gas)set out in UNRTDG2.2.1.2 accords with that of gas in GHS: “a
substance that at 50 °C has a vapor pressure greater than 300 kPa (absolute pressure); or is
completely gaseous at 20 °C at a standard pressure of 101.3 kPa”. On the other hand, UNRTDG
does not provide the definition of gases under pressure, which are newly defined by GHS as
“gases with vapor pressure of 200 kPa or more”.
(6)Sources of information for classification results under conventional systems
These depend on the design selected by the manufacturers. Categorization of Gases Under
Pressure is performed by using external data as complement.
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