The simple answer is that mercaptan is not harmful at the levels used when odorizing natural gas. The nose can detect mercaptan at a 1.6 PPB (parts per billion), and the typical range of odorants in natural gas ranges from 0-10 ppm (parts per million).

Natural gas in its native state is colorless and odorless. Mercaptan is the additive that is added to natural gas to make it easier to detect in case of a leak. The most important thing to know about mercaptan is that it stinks.

Mercaptan MSDS The gas has a smell at an odor threshold of 1 ppb, and OSHA has a Permissible Exposure Limit for mercaptan of 10 ppm.

Ethanethiol (EM), commonly known as ethyl mercaptan is used in Liquefied petroleum gas (LPG), and resembles odor of leeks, onions, durian, or cooked cabbage. Methanethiol, commonly known as methyl mercaptan, is added to natural gas as an odorant, usually in mixtures containing methane.

It may be an odorant injection system, a wick-style odorizer, or a bypass odorizer. The odorant is the chemical injected into the gas to deliver the rotten-egg odor. Over many years, a class of organosulfur compounds known as mercaptans and some non-sulfur compounds became the standard chemicals to odorize natural gas.

mercaptan

The meter outside you houses a regulator on it which helps control the flow of gas into your home or business. There are times it will normally bleed-off or “burp” small amounts of gas to keep the pressure from building too high in your home. This is normal. So if you are near a meter you might smell it.

If you smell a natural gas odor, hear the hissing sound of gas escaping or see other signs of a leak:

1. IMMEDIATELY EVACUATE the area, and from a safe location either call 911 or SoCalGas at 1-800-427-2200.
2. DON’T smoke, or light a match, candle or other flame.

When a gas leak occurs and the gas does not burn up completely (this usually happens when there is faulty installation or a ventilation problem), a byproduct becomes present in your air space: carbon monoxide. Carbon monoxide poisoning can kill you. This is why a gas leak can kill you.

The smell should dissipate within a few hours. If it doesn’t, contact your gas company and report the problem – there may be a more extensive leak. If anyone is suffering from nausea, headaches, dizziness or flu-like symptoms, call 911 immediately, as these are sign of carbon monoxide poisoning.

Depending on the labor rates in your area, it could be up to 4 hours. It takes 10 minutes to replace a flex gas line, which probably falls into the minimum service call for most contractors.