Specific Properties of Selected Industrial Gases:

Someone who uses gases must have a thorough knowledge of their chemical properties to manage a controlled operation. Its flammable range and ignition temperature must be known if the gas is flammable.

The lower flammable limit is the smallest percent of the gas in air that could ignite while exposed to the ignition temperature.  An upper flammable limit is the point above that the combination is too rich in fuel to ignite.  The range among these two limits is the explosive, or flammable, range.   A most violent explosion will occur at concentrations about the center of the flammable range.    Sources of heat which might cause temperatures that exceed the ignition temperature have to be prevented, as well as gas-air mixtures which are inside the flammable range.

The physiological effects of the gas must be known, not only categories of reactions, but also severity of reactions. Whole employees who handle gas should be familiar along with its effects, or recommended control measures.

The chemical reactivity of the gas must be known.  This involves knowledge of the materials which are resistant to its chemical effects, a material along with which it reacts, and how it reacts along with such materials.   A few gases become unstable at high pressures, or others become more corrosive at high temperatures.

The word TLV (Threshold Limit Value) is sometimes used and is described as:  The highest time-weighted average concentration of an air contaminant that if breathed for a normal working day is unlikely to result in health injury to the average person, either at the time or after years of exposure.

The subsequent discussion addresses a few of the more generally used gases, and elaborates the exact chemical properties and features which are important for accident avoided.