Standard Test Methods for Natural Gas Odor Intensity

Federal regulations⁴ state: “A combustible gas in a distribution line must contain a natural odorant or be odorized so that at a concentration in air of one-fifth of the lower explosive limit, the gas is readily detectable by a person with a normal sense of smell.” These regulations state further that “each operator shall conduct periodic sampling of combustible gases to assure the proper concentration of odorant in accordance with this section.” Additionally, a number of states have enacted legislation that requires natural gas to be odorized so that it is detectable at concentrations less than one fifth of the lower explosive limit.⁵ While regulations do not specify the exact method for determining compliance, it has been documented that compliance testing must be olfactory in nature.⁶

These test methods cover procedures to measure the odor level of natural gas by way of olfactory determination. No direct correlation may be ascertained between these test methods and those methods available or under development that quantitatively measure the concentration of sulfur compounds in natural gas.

These test methods outline general procedures to measure the odor detection levels of natural gas. It is the responsibility of persons using these test methods to develop and maintain equipment and specific operating procedures to ensure public safety and compliance with all appropriate regulations.