Oxygen content, explosive hazard

Simple asphyxiant. Some gases and vapours present at high concentrations act as asphyxiants by reducing the oxygen content of air. Many of these are odourless and colourless. Many also pose a fire or explosion risk, often at values below which asphyxiation can occur. (Although capable of asphyxiation, they are not considered to be substances hazardous to health under COSHH.)... 

The ACGIH has not assigned a numerical threshold limit value (TLV) for occupational exposure to ethane because the limiting factor is the available oxygen, the minimal content which should be 18% by volume under normal atmospheric pressure at concentrations below those required to produce severe oxygen deprivation, ethane presents an explosive hazard. ... 

So, a purging process (performed with the protective gas maintaining the positive pressure differential during operation) shall flush the hazardous mixture inside the p enclosure before energizing the apparatus. More precisely during the purging process, and with air as protective gas, the potentially explosive atmosphere inside the enclosure shall be diluted to a safe value of gas concentration, i.e. 25 per cent of LEL, or, with inert gas as protective gas, the oxygen content of the atmosphere inside the enclosure shall be reduced to 2 per cent (v/v). 

Diisopropyl peroxydicarbonate can present a greater fire hazard than explosion danger. It has an active oxygen content of 7.8%. When warmed above its melting point to... 

Employers are responsible for the safe use of compressed gas cylinders and liquid containers and their contents. Compressed gas hazards include oxygen displacement, explosion, and toxic effects. There is also the hazard of a ruptured cylinder. Employers must evaluate the compressed gas-hazards and have an emergency response plan that defines procedures and responsibilities to address emergencies. 

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