Gas odorant fade information

The purpose of this section is to provide customers and contractors who work on natural gas piping, equipment and appliances, with additional safety information on natural gas odorant and the potential for odor fade.

Louisville Gas and Electric Company odorizes natural gas that is delivered through its natural gas distribution system. The odorization of natural gas for leak detection and public safety is regulated by the Department of Transportation and the Kentucky Public Service Commission. LG&E routinely monitors odor concentration in the gas distribution system to ensure compliance with regulatory requirements.

Do not rely on your sense of smell alone

Even though odorant is added to natural gas to assist in the detection of leaks, you should not rely solely on the sense of smell to determine if a gas leak has occurred or is occurring. Some persons may not be able to detect the odorant because of a diminished sense of smell or because the odorant smell is being masked by other odors. In addition, there may be rare conditions, such as odor fade (loss of odorant), which may occur and may cause the odor to diminish so that it is not detectable.

Odor fade or loss of odorant

Odor fade or loss of odorant can occur when physical and/or chemical processes including adsorption and oxidation cause the level of odorant in the gas to be reduced. This can occur more frequently in installations of new gas pipe than in existing pipe. It is more likely to occur in new steel pipe of larger diameters and longer lengths. Odorant fade can also occur in plastic pipe and in smaller and/or shorter pipe installations. Conditioning of new pipeline installations or additions of new piping segments may be needed before the pipe is placed into service to prevent odorant fade.

Soil may also cause odorant fade if a natural gas leak occurs underground. Other factors that could cause odorant fade include the construction and configuration of a customer's gas facilities; the presence of rust, moisture, liquids or other substances in the pipe; and gas composition, pressure or flow. Little or no gas flow over an extended period of time can also result in odorant fade until gas flow increases or becomes more frequent.

Gas line purge

Never purge the contents of a gas line into a confined space. Only a licensed, qualified professional should purge a gas line. Purging should be done in a well-ventilated area or by venting the contents to the outside atmosphere. Gas detection equipment should always be used during purging operations or when working on gas piping systems to ensure that no natural gas is present that may result in a combustible or hazardous atmosphere.


Consult your local fuel gas code for more information. When installing gas appliances or equipment, the manufacturer's instruction manual should be followed in accordance with the local code requirements.