NIOSH - Odor Fade in Natural Gas and Propane

Detection of Natural Gas and Propane

• Equipment should be used to detect natural gas and propane rather than relying on smell.
• Daily calibration of detection meters is essential for accurate readings.
• Odorant may dissipate into various building materials like soil, concrete, and drywall.

Odorants Used

• Methyl mercaptan is the odorant for natural gas.
• Ethyl mercaptan is the odorant for propane.
• Both odorants have a distinctive smell similar to rotten eggs or cabbage.

Odor Fade

• Occurs through absorption or oxidation processes.
• More prevalent in newer, larger steel pipes and tanks, as well as polyethylene materials.

Reducing Odor Fade

• Conditioning of equipment is recommended to minimize odor fade.

Propane Specifics

• Chemical formula: C3H8
• UN ID number: 1075
• Emergency Response Guide (ERG) reference: Guide 115
• Liquid propane is used in vehicles.
• Propane is 1.5 times heavier than air, posing risks of simple asphyxiation.

Vapor Characteristics

• Liquid propane gas (LPG) vaporizes at -44°F.
• 1 gallon of LPG can produce 270 gallons of vapor.
• A home grill using 4.75 gallons of LPG can generate a vapor cloud of 1,274 gallons.
• Vapor can extend beyond the visible cloud.

Meter Usage Guidelines

• Suggested meter: Ventis 3 gas detector.
• Multi-gas detection should multiply Lower Explosive Limit (LEL) value by 2.
• Use the meter slowly and at low levels to collect softball-sized samples.
• A low O2 sensor indicates an air deficiency.
• If one or multiple sensors trigger alarms, consider activating Hazmat protocols.