Common industrial chemicals are often monitored for combustion (as a percentage of the lower explosive limit (% LEL), but should be monitored in ppm to protect personnel to OSHA standards.
For example, monitoring Toluene at 10% LEL results in an alarm setting of 1100 ppm – 11 times the TWA limit of 100 ppm, and over 2 times the IDLH level.
All of the information below is from the NIOSH Pocket Guide to Hazardous Chemicals available at https://www.cdc.gov/niosh/npg/search.html
- 100 LEL % = 1,000,000 ppm
** PPM = LEL % by Vol x % LEL . Example Toluene 1.1% LEL x 100% LEL (1,000,000 PPM) = 11,000 ppm
*** IDLH – immediately dangerous to life or health concentrations
TWA – time weighted average – the average exposure that must not be exceeded during any
8 hour work shift of a 40-hour work week.
When it comes to gas monitoring, many facilities focus primarily on measuring for explosive limits to reduce the risk of fire or combustion. While this is critical for protecting infrastructure, it does not always ensure the safety of the people working inside the plant. A gas can be present at levels far below its lower explosive limit (LEL) yet still be highly toxic to personnel. Relying only on combustion monitoring can create a false sense of security.
Toxic hazards appear at much lower concentrations than those required for an explosive event. For example, hydrogen sulfide (H₂S) and carbon monoxide (CO) can be deadly at parts-per-million (ppm) levels—well below the point where they would ignite. Personnel may already be experiencing harmful health effects long before standard LEL detectors register a concern.
This is why comprehensive gas detection strategies must account for both toxicity and flammability. Installing toxic gas sensors alongside combustible gas monitors ensures that workers are protected from immediate health risks as well as catastrophic fire or explosion events. It also ensures compliance with occupational safety standards, helping organizations avoid costly downtime, regulatory penalties, or reputational damage.
The right solution often requires a layered approach of:
- infrared sensors
- catalytic bead sensors
- electrochemical cells
Together this combination covers the full spectrum of hazards. By combining technologies and monitoring strategies, facilities can achieve both early toxic gas warning and reliable explosive limit detection.
Ultimately, protecting a plant is not enough—protecting people must come first. Investing in dual toxic and combustible gas detection ensures that employees are safeguarded in real time, allowing organizations to build a safer, more resilient workplace.
At ETAPII, we understand that safeguarding your facility requires more than just explosive gas monitoring. Our team provides advanced detection solutions that protect against both toxic and combustible hazards, helping you create a safer workplace for your personnel. From selecting the right sensors to integrating complete fire and gas detection systems, ETAPII can guide you every step of the way. Contact us today to learn more about how we can help you implement the right solutions for your operations.