Odorization

the process of imparting a characteristic odor to a gas. The most common industrial and household fuels are odorless hydrocarbon gases, which makes it impossible to detect leaks in gas mains and devices or to determine the presence of gas in homes and work areas before the buildup of an explosive or harmful concentration. Odorization increases the safety of using gas by ensuring detection of leaks.

The odorization process involves the addition of odorants to the gas. A drop-type apparatus, in which the odorant is fed in the form of drops into the gas line from a tank and subsequently evaporated in the gas flow, is usually used to odorize natural and synthetic gases. For liquefied gases there is periodic (batch) and continuous odorization apparatus of the injection and ejection types.

As of 1974, the standard adopted by the USSR for odorization of natural hydrocarbon gases with ethyl mercaptan (EMC) was 16 mg/m³. The standard for liquefied gases was 60 g per ton if the liquefied gas contains up to 60 percent propane and more than 40 percent butane and other components and 90 g per ton if the propane content exceeds 60 percent and the content of butane and other components is up to 40 percent. The degree of odorization is monitored by organoleptic, chemical, and physicochemical methods.

Air is odorized when testing pipelines and tanks for airtightness; it is also odorized in airconditioning systems. For example, a pine scent is produced by the addition of pine extract, and ozonization imparts a fresh scent to air (0.01–0.05 parts ozone per million parts air).