The dangers caused by lack of oxygen
Oxygen is essential to life. Despite the fact that a healthy person can survive a short exposure to oxygen as low as about 16%, sufficient oxygen supply must be present in any atmosphere breathed by humans. Since a drop in the oxygen level is not accompanied by signals, it is impossible for a human being to detect the signs.
Causes and prevention of lack of oxygen
The lack of oxygen can be avoided by respecting the following instructions:
Gas leaks, other than oxygen, automatically lead to lack of oxygen. New equipment that uses inert gases, or any other gas, must be thoroughly inspected for leaks with interval gas pressure drop testers, leak testers used with the appropriate sensing fluid, compatible with equipment in question.
All equipment, including hose and hose connections, must be properly mounted. Hoses and other equipment must be kept leak-free and protected against damage. All maintenance and repair work must be done by experienced and qualified personnel.
When the work period is over, the cylinder or tube supply valve must be turned off to prevent leakage between two work periods. Do not consider valves on welding equipment as closing valves for gas supply. Gas cylinders must not be handled suddenly, knocked over or put on the side.
A small amount of liquefied gas can turn into a large amount of gas. Liquids can escape and quickly cause a lack of oxygen. Tanks and equipment for the storage and handling of liquid gases must be carefully inspected and maintained in accordance with the provisions of the regulations and recommendations.
Ventilated gases often have low oxygen levels. Work should not take place in this type of atmosphere.
Lack of oxygen occurs when site facilities, such as containers, are purged with nitrogen or other inert gases for future repair.
Processes that include liquid nitrogen spraying, such as food cooling, soil freezing, cryogenic surgery, plasma preservation, automatically result in oxygen deficient atmospheres. Nobody should enter these areas without proper respiratory equipment, even if the atmosphere suffers only a slight lack of oxygen. Areas of this type must be equipped with appropriate detectors and alarm systems.
Gas welding and heating extract oxygen from the air. These processes can induce a lack of oxygen if the workplace is small and poorly ventilated.
The removal of argon, carbon dioxide and other cold gases from deep containers and pits can be difficult because these gases are denser than air. The air blown into the bottom of these spaces tends to rise through the dense gas without moving it. This means that purging can take much longer than expected.