Why is compressed oxygen flammable

Hydrogen gas levels above 75 percent are too "rich" to burn. The flammable range of any gas is widened in the presence of oxidizing gases such as oxygen or chlorine and by higher temperatures or pressures. For example, the flammable range of hydrogen in oxygen gas is 4 to 85 percent and the flammable range of hydrogen in chlorine gas is 4.

Ignition Source: For a flammable gas within its flammable limits in air or oxidizing gas to ignite, an ignition source must be present. There are many possible ignition sources in most workplaces including open flames, sparks and hot surfaces. The auto-ignition or ignition temperature of a gas is the minimum temperature at which the gas self-ignites without any obvious ignition sources.

Some gases have very low auto-ignition temperatures. Some compressed gases, such as silane and diborane, are pyrophoric - they can ignite spontaneously in air.

Flash-back can occur with flammable gases. Many flammable compressed gases are heavier than air. If a cylinder leaks in a poorly ventilated area, these gases can settle and collect in sewers, pits, trenches, basements or other low areas. The gas trail can spread far from the cylinder.

If the gas trail contacts an ignition source, the fire produced can flash back to the cylinder. Oxidizing gases include any gases containing oxygen at higher than atmospheric concentrations above percent , nitrogen oxides, and halogen gases such as chlorine and fluorine. These gases can react rapidly and violently with combustible materials such as the following:.

The normal oxygen content in air is 21 percent. At slightly higher oxygen concentrations, for example 25 percent, combustible materials, including clothing fabrics, ignite more easily and burn much faster.

Fires in atmospheres enriched with oxidizing gases are very hard to extinguish and can spread rapidly. Some pure compressed gases are chemically unstable. If exposed to slight temperature or pressure increases, or mechanical shock, they can readily undergo certain types of chemical reactions such as polymerization or decomposition.

These reactions may become violent, resulting in fire or explosion. Some dangerously reactive gases have other chemicals, called inhibitors, added to prevent these hazardous reactions. Common dangerously reactive gases are acetylene, 1,3-butadiene, methyl acetylene, vinyl chloride, tetrafluoroethylene and vinyl fluoride.

Many compressed gases are toxic or very toxic. They could cause various health problems depending on the specific gas, its concentration, the length of exposure and the route of exposure inhalation, eye or skin contact. Contact between the skin or eye and liquefied gases in liquid form can freeze the tissue and result in a burn-like injury. Inert gases, such as argon, helium, neon and nitrogen, are not toxic and do not burn or explode.

Yet they can cause injury or death if they are present in sufficiently high concentrations. They can displace enough air to reduce oxygen levels. If oxygen levels are low enough, people entering the area can lose consciousness or die from asphyxiation. Low oxygen levels can particularly be a problem in poorly ventilated, confined spaces.

Some compressed gases are corrosive. They can burn and destroy body tissues on contact. Corrosive gases can also attack and corrode metals. Common corrosive gases include ammonia, hydrogen chloride, chlorine and methylamine. Add a badge to your website or intranet so your workers can quickly find answers to their health and safety questions. Although every effort is made to ensure the accuracy, currency and completeness of the information, CCOHS does not guarantee, warrant, represent or undertake that the information provided is correct, accurate or current.

CCOHS is not liable for any loss, claim, or demand arising directly or indirectly from any use or reliance upon the information. OSH Answers Fact Sheets Easy-to-read, question-and-answer fact sheets covering a wide range of workplace health and safety topics, from hazards to diseases to ergonomics to workplace promotion. Search all fact sheets: Search. Type a word, a phrase, or ask a question. Liquefied Gases Liquefied gases are gases which can become liquids at normal temperatures when they are inside cylinders under pressure.

Non-Liquefied Gases Non-liquefied gases are also known as compressed, pressurized or permanent gases. Dissolved Gases Acetylene is the only common dissolved gas. Appropriate care in the handling and storage of compressed gas cylinders is essential. The following is an overview of the hazards to be avoided when handling and storing compressed gases:. See Air Liquide for more information. Before using cylinders, read all label information and safety data sheets SDSs associated with the gas being used.

The cylinder valve outlet connections are designed to prevent mixing of incompatible gases. The outlet threads vary in diameter; some are internal and some are external; some are right-handed and some are left-handed.

Generally, right-handed threads are used for fuel gases. Most leaks occur at the valve in the top of the cylinder and may involve the valve threads valve stem, valve outlet, or pressure relief devices.