CHAPTER 2 UNDERSTANDING UTILITY NATURAL GAS
volumes of gas can create flammable atmospheres, and the large volume of gas can quickly make the area oxygen-deficient creating the hazards of low oxygen discussed earlier.
Avoid contact of exposed body surfaces with supercold gases or liquids as
they leak from the container or pipe. They can cause severe "super" frostbite injuries. Direct contact with liquid natural gas, supercold vapor, or cold equip- ment can cause serious tissue damage. Frozen tissue is painless and appears yellow and waxy. The burn site may become painful and will turn pink or red as it warms. Cryogenic burns need medical attention. Assistance for a cryogenic injury should be obtained as soon as possible. No cryogenic LNG burn is insignificant. Evaluation and treatment of damaged tissue needs proper medical attention because incorrect first aid practices can make the situation worse.
Reactivity
Natural gas, for the most part, is stable and rarely reacts with other chemicals. However, a few chemicals (oxidizers) can make it extremely dangerous. Nat- ural gas is a fuel, so any strong oxidizers, especially in the gaseous state, such as oxygen-enriched atmospheres, fluorine and chlorine, can make natural gas very explosive. Chlorine and natural gas can explode in sunlight, and fluorine and natural gas and chlorine can explode on contact.
Oxygen-enriched Atmospheres
The most common oxidizer is oxygen present in the air in concentrations of 21%. At this concentration natural gas is flammable and becomes even more so as the oxygen increases in the atmosphere. Flammable atmospheres become extremely explosive in oxygen-enriched situations. In such atmos- pheres the flammable range of products like natural gas will widen and the ignition temperature will become lower.
SUMMARY
Responding to gas emergencies is as complicated a task as any hazardous materials event. Responders must recognize that natural gas is present and must understand its physical and chemical properties. This knowledge will enable them to properly assess the hazard, analyze the risk, and operate safely at these incidents.
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