--- title: Gas Analyser Safety: Hazardous Areas, Inerting, SIL url: https://www.sarveshanalytics.com/learn/track-safety.html description: Flammability limits, limiting oxygen concentration, inerting and purging, hazardous-area zones and gas groups, protection concepts, SIL and oxygen hazards. updated: 2026-11-03 source: html --- Learn ยท Track 6 of 8 # Safety and hazardous areas Flammability, inerting, hazardous areas, protection concepts, SIL and oxygen hazards. 8 lessons About 25 min ## What this track covers Gas analysers are often chosen because a process is dangerous, and installed where the danger is. This track explains the hazards, the vocabulary of area classification and the limits of what an analyser can promise, including what it means when a supplier makes no SIL claim. ## Lessons, in order 1. [ **Flammability, explosive limits and gas safety basics** A flammable gas burns only when fuel, oxygen and an ignition source are present and the fuel-air mixture lies between the lower and upper explosive limits (LEL and UEL). Beginner*3 min*](https://www.sarveshanalytics.com/learn/flammability-explosive-limits-and-gas-safety-basics.html) 2. [ **What is limiting oxygen concentration (LOC)?** The limiting oxygen concentration (LOC) is the oxygen level below which a flammable vapour or dust cannot sustain a flame. Beginner*3 min*](https://www.sarveshanalytics.com/learn/what-is-limiting-oxygen-concentration.html) 3. [ **Inerting and purging: how they work and how to prove them** Inerting keeps a vessel's oxygen below the limiting oxygen concentration by filling it with nitrogen or another inert gas. Intermediate*3 min*](https://www.sarveshanalytics.com/learn/inerting-and-purging-how-they-work.html) 4. [ **Hazardous area classification: zones, gas groups, T-Classes** Area classification says how likely an explosive atmosphere is (Zone 0, 1 or 2 for gas), what gas it could be (group IIA, IIB or IIC) and how hot equipment may get (T1 to T6, 450 to 85 C). Intermediate*3 min*](https://www.sarveshanalytics.com/learn/hazardous-area-classification-zones-gas-groups-temperature-classes.html) 5. [ **Hazardous area gas analysers explained** A hazardous area analyser is built so it cannot ignite flammable gas. Intermediate*4 min*](https://www.sarveshanalytics.com/learn/hazardous-area-gas-analysers-explained.html) 6. [ **Protection concepts: flameproof, intrinsic safety, purging** Hazardous-area equipment avoids ignition in one of three ways: contain an explosion (flameproof, Ex d), prevent sparks and heat (increased safety Ex e, non-sparking Ex n or ec, encapsulation Ex m), or limit energy (intrinsic safety Ex i), or keep the gas out (pressurised or purged enclosures, Ex p). Advanced*3 min*](https://www.sarveshanalytics.com/learn/protection-concepts-flameproof-intrinsic-safety-and-purging.html) 7. [ **What SIL means for gas analysers, and what it does not** A safety integrity level (SIL 1 to 4) states how reliably a safety instrumented function does its job on demand. Advanced*3 min*](https://www.sarveshanalytics.com/learn/what-sil-means-for-gas-analysers.html) 8. [ **Oxygen enrichment and oxygen deficiency hazards** Too much oxygen makes materials ignite more easily and burn fiercely; above about 23.5 % is commonly treated as oxygen-enriched. Beginner*3 min*](https://www.sarveshanalytics.com/learn/oxygen-enrichment-and-oxygen-deficiency-hazards.html) Next track: [Process primers](https://www.sarveshanalytics.com/learn/track-process-primers.html)