Acetylene is a colourless gas with a faint ether odour in its pure form and a garlic odour in its industrial form due to impurities. In air, it burns with a smoky flame. In oxygen, it burns with a bright, intensely hot flame in oxygen, leading to its major use as the fuel in oxy-acetylene welding/cutting applications. Acetylene is non-poisonous and mildly anaesthetic in its pure form. Any toxic effects from acetylene are due to impurities (such as phosphine) in its industrial form, as well as carbon monoxide production due to combustion in a confined space.
Acetylene Characteristics
Synonyms
Ethyne, Ethine
CAS No.
74-86-2
Chemical Formula
C2H2
Vapour Density
0.9 (air = 1)
Safe Work Australia ES
TWA
Not applicable – simple asphyxiant
STEL
Not applicable – simple asphyxiant
Flammable Limits
LEL
2.3 % by volume
UEL
100 % by volume (1)
Equipment Group
IIC
Temperature Classification
T2
Chemical/Physical Properties
Acetylene is a colourless gas with a faint ether odour in its pure form, and a garlic odour in its industrial form. It burns in air with a smoky flame and in oxygen with a bright, intensely hot flame.
Hazardous Properties
Acetylene is non-poisonous and mildly anaesthetic in its pure form. Any toxic effects are due to impurities (such as phosphine) in its industrial form, and carbon monoxide due to combustion in a confined space.
Occurrence/Uses
The high temperature of its flame when burnt in oxygen leads to its major use as the fuel in oxy-acetylene welding/cutting applications.
Detectors Available
Catalytic bead (0 – 100% LEL)
Gas detector tube (50 – 1,000 ppm)
Suggested Alarm Levels
Lo: 5 % LEL
Hi: 10 % LEL
Notes
(1) Acetylene is unstable when pressurised and, under certain conditions (intense heat and shockwave), can decompose explosively without the presence of oxygen.
