What is odor fade? What causes odor loss in odorized natural gas?

 In Natural Gas Odorization

What is odor fade? Odor fade refers to the diminishing odor of odorized gas.

Smelling natural gas is the first indicator that a gas leak may be present, but if you can’t smell it, the warning system doesn’t work. The question becomes, why can’t you smell the odorized gas?

This article will explore odor fade, its implications for gas safety, and why you may not detect odorized gas.

 Are you in need of an odorizer?

Natural Gas Odorization

Gas companies odorize natural gas (i.e., inject odorant into the gas) so that people can smell it for safety reasons. The process of natural gas odorization, particularly with a modern odorant injection system, provides an accurate injection of the correct amount of odorant. However, at times, the gas does not smell, and while the tendency may be to look at the odorizer as the cause, pipeline conditions and other circumstances may impede smelling the odorant in gas.

Odor Fade

natural gas pickling to odorize natural gas

GPL Odorizers manufactures various odorant injection systems, including pickling and temporary odorization systems.

Odor fade is a condition where there is a loss of odorant in the gas stream to such a level that the gas becomes undetectable. In this case, the odorant compound may decompose and change composition or be physically removed or pulled from the gas. In any case, there is a significant loss of odor. These are primarily chemical adsorption, absorption, or oxidation processes occurring in generally new gas pipe installations. While odor fade is more common in new large-diameter steel pipes of long pipelines, it can also happen in smaller-diameter PE (polyethylene) lines.

Other situations that may cause odor fade are:

  • During some gas leaks, the odorant may strip from the gas when seeping into some soils or concrete.
  • Rust, moisture, liquids, or other foreign substances in the pipe can create a loss of odorant.
  • Some odorizers cannot correctly odorize during low or intermittent gas flow conditions, causing odor to fade.

Gas companies routinely perform pipe pickling to prepare the new pipelines before use. This process is also called pipeline conditioning or pre-odorization. If your company needs natural gas pipe pickling or pipeline conditioning, request a quote here.

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Odor Loss

odor loss or odor fade

Odor fade or odor loss? They’re different!

Other conditions can cause odor loss, and while they are not “odor fade,” they present the risk of failing to smell natural gas odorant.

  1. Olfactory Fatigue – Olfactory fatigue, or odor fatigue, occurs when prolonged exposure to a specific compound occurs. It is usually temporary and customary for people who work around natural gas odorants. In these cases, the person may be unable to recognize that an odorant is present or that there have been changes in the odor level. Employers are encouraged to have gas detectors in these cases where their employees are routinely exposed to odorants.
  2. Smell Disorders—People with anosmia cannot smell, and those with hyposmia have a diminished capacity to smell. In either case, the sufferer may likely be unable to detect the odorant injected into the gas.
  3. Sleeping – People in deep sleep stages will likely not smell odorant in a gas leak.
  4. Odor Masking – Odor masking occurs when one or more gas stream compounds can change, reducing the perceived odorant smell. In this case, the odorant may still be present, but the scent has changed.

Gas detectors and other measures are always available to keep people safe, especially for those with a smell disorder and those concerned about odor fatigue or odor masking. Additionally, gas detectors help those who may fail to smell while sleeping.

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