Mercaptan Gas Detector (Methyl Mercaptan, Methanethiol)

Mercaptan Gas Detector, Methanethiol Gas Detector, Methyl Mercaptan Gas Meter -

Mercaptan Gas Detector (Methyl Mercaptan, Methanethiol)

Mercaptan gas is best known for its pungent smell in domestically supplied natural gas that comes into our home. It is very aromatic and because it has an extremely pungent odor that smell like skunk, garlic or some type of rotten organic matter.  Because of this, it is used as a warning odor or "stench gas" in natural gas, propane, and various other petrochemical products. Mercaptan gas on its own it very useful to the pharmaceutical industry, livestock feed, fungicide, and plastics industries. It is a toxic gas therefore gas exposure to mercaptan is important to be detected.

Pros

Cons

  • Mercaptan gas can be detected by a human down to 1 part per billion (1ppb), low human odor threshold
  • Mercaptan gas detectors are used to detect the amount of CH2S present to limit gas exposure dangers
  • Mercaptan gas detectors may be useful in settings where CH2S is used such as in livestock feed, plastics, petrochemical industry and sanitization
  • Mercaptan gas detectors are expensive
  • Do not confuse Ethyl and Methyl Mercaptan
  • Mercaptan gas detectors need regular calibration and bump testing
  • It has a terrible putrid smell making hard to work with

The Best Mercaptan Gas Detector?

There are a variety of mercaptan gas detectors on the market. They can be purchased from several online retailers. Some examples of reputable CH4S gas detectors include:

What are the Mercaptan Gas Names?

The common mercaptan, is also known as Methyl Mercaptan, Mercaptan, Mercaptanthiol. Its chemical formula is CH4S sometimes written as CH3SH, MeSH. There is also Ethyl Mercaptan, which is Ethanethiol and a different gas with the chemical formula C2H4S. Make sure not to confuse them - but both has a very pungent smell.

  • The single biggest use of CH4S is for production of synthetic methionine as a chicken feed supplement. Methionine is an amino acid used to make protein.

  • Used in industrial situations to produce pesticides, fungicides, plastics and animal feed additives.
  • In the natural world, it is found near decaying organic matter and thus found in natural gas, crude oil and some coal tar deposits.

Why are Mercaptan Gas Detector becoming useful?

More demand for mercaptan gas detectors is increase because the market demand for the methyl mercaptan is also growing. This is due to its application in the poultry and livestock feed as a result of growing popular and food demand. Other Mercaptan gas detector demand is coming from applications in pesticide and fungicide industries, applications in mining operations for communication, jet fuel additives.

What is in a Mercaptan Gas Sensor?

Like most gas detectors, a CH4S gas detector is composed of several key parts which includes the sensor, computer and display. The mercaptan gas sensor is critical to detecting the presence of CH4S gas molecules. The gas causes a chemical reaction in electrochemical sensors, resulting in a current that is directly proportional to the gas concentration present. The sensors consume extremely little power and respond well to a variety of gas concentrations across a wide range of environmental conditions.

Is Methyl Mercaptan Gas Poisonous?

Yes.

Based on the CDC, CH4S gas is highly irritant when it contacts moist tissues such as the eyes, skin, and upper respiratory tract. It can also induce headache, dizziness, nausea, vomiting, coma, and death.

At very high concentrations it is highly toxic with a impressive odor threshold of 1 ppb being reported.The United States OSHA Ceiling Limit is listed as 10 ppm. NIOSH REL is 0.5ppm.

Have There Been Mercaptan Accidents?

Yes there have been. Some notable incidents includes:

  • In 2022, South Jersey experienced a mercaptan leak and sickened many people.
  • In 2014, the Du Pont company experience a methyl mercaptan leak killing 4 workers
  • In 2001, a rail cart exploded with methyl mercaptan killing several people.

What are the Mercaptan Sensor Interference Gases?

Unfortunately, electrochemical sensors are not completely selective, and they respond to other gases present in the environment.

For mercaptanthiol, it has a strong cross sensitivity to H2S. See the table below.

How Can I Calibrate a Methyl Mercaptan Detector?

Although methyl mercaptan standards are not available for calibration, H2S gas standards can be utilized because a CH4S gas sensor responds 1:2 to H2S. This ratio may change slightly with different sensor manufacturers and ranges. 

What Does Methyl Mercaptan Smell Like?

Mercaptan has a very foul smell, some even say the worst pungent smell on the planet. 

People often describe the smell similar to skunk, garlic or some type of rotten organic matter.  It definitely has resemblance to other sulfur smells such as hydrogen sulfide H2S which is a common gas release in sewer and from biological decomposition. 

Encyclopedia.com describes it as foul-smelling gas with the odor of rotten cabbage released from decaying animal and vegetable matter. 

    How is Methyl Mercaptan Gas Generated?

    It is made by reacting of hydrogen sulfide with methanol. It is found in the natural world also in very small quantities.

    Is Methyl Mercaptan Gas Explosive?

    Yes it is explosive at %vol concentrations. For example, the lower explosive limit (LEL) is 3.9% and the upper explosive limit (UEL) is 21.8%.

    What is the Biggest Use for Methyl Mercaptan Gas?

    The single biggest use of CH4S is for production of synthetic methionine as a chicken feed supplement. Methionine is an amino acid used to make protein.

    What Makes Up a Methyl Mercaptan Gas Detector?

    Like most detectors, a mercaptan gas detector is composed of several key parts.

    • The sensor: the sensor is critical to detecting the presence of the CH2S gas in the first place
    • The output: after the sensor recognizes the presence of the mercaptan gas, it pushes that information to a different component that converts that concentration to a reading interpretable by people
    • The energy supply: the energy supply allows the device to continue working. This can vary depending on if the detector is portable or fixed

    Is Methyl Mercaptan and Ethyl Mercaptan the Same Gas?

    No. They are similar but not the same.

    Methyl Mercaptan, Mercaptan, Mercaptanthiol as the chemical formula of CH4S sometimes written as CH3SH, MeSH. Ethyl Mercaptan, also known as Ethanethiol is a different gas with the chemical formula C2H4S. 

    They are both alkylthiols with low olfactory odor thresholds and sulfurous sweaty, skunky aromas. A fun fact is that they are both found to make an important contribution to the aroma of wine.

    Final Words

    • Mercaptan gas can be detected by a human down to 1 part per billion (1ppb), low human odor threshold
    • Mercaptan gas detectors are used to detect the amount of CH2S present to limit gas exposure dangers
    • Mercaptan gas detectors may be useful in settings where CH2S is used such as in livestock feed, plastics, petrochemical industry and sanitization
    • Mercaptan gas detectors are expensive
    • Do not confuse Ethyl and Methyl Mercaptan
    • Mercaptan gas detectors need regular calibration and bump testing
    • It has a terrible putrid smell making hard to work with

    About the Author

    Dr. Koz is the President of FORENSICS DETECTORS, where the company operates from the scenic Palos Verdes Peninsula in Los Angeles, California. He is a subject matter expert on gas sensor technology, gas detectors, gas meters, and gas analyzers. He has been designing, building, manufacturing, and testing toxic gas detection systems for over 20 years.

    gas detector expert

    Every day is a blessing for Dr. Koz. He loves to help customers solve their unique problems. Dr. Koz also loves spending time with his wife and his three children going to the beach, grilling burgers, and having a cold beer. 

    Read more about Forensics Detectors.

    Email:  drkoz@forensicsdetectors.com
    Phone: +1 424-341-3886


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