Understanding hazardous-location classifications and explosion-proof terminology is critical when specifying and installing certified cameras and equipment in high-risk industrial environments. This glossary collects the key terms engineers, safety managers and procurement teams need.
Class I — Locations with flammable gases or vapors (ex: refineries, LNG systems).
Class II — Locations with combustible dust (grain, coal, metal dust).
Class III — Locations with ignitable fibers or flyings (textile, wood).
Division 1 — Hazardous material is present during normal operation (high risk).
Division 2 — Hazard present only in abnormal conditions (lower risk).
Group A — Acetylene (highest hazard for group A).
Group B — Hydrogen and similar gases.
Group C — Ethylene and similar gases.
Group D — Propane, gasoline and similar (common industrial gases).
Dust Groups E/F/G — classification for types of combustible dust.
Zone 0 — Explosive atmosphere present continuously.
Zone 1 — Explosive atmosphere likely during normal operation.
Zone 2 — Explosive atmosphere unlikely during normal operation.
Zone 20 / 21 / 22 — Equivalent zones for combustible dust (20 = continuous).
Gas Group IIA / IIB / IIC — Increasing hazard (IIC includes hydrogen/acetylene).
Equipment Protection Level (EPL) — e.g., Ga/Gb/Gc for gases; Da/Db/Dc for dust — used in IEC/ATEX to express protection performance.
Category 1/2/3 — ATEX equipment categories mapped to Zones.
IECEx — International certification scheme harmonized with IEC 60079 series.
T1 — T6 — Maximum surface temperatures; T6 = 85°C (lowest), T1 = 450°C (highest).
Why it matters: The T-rating must be lower than the ignition temperature of the ambient flammable material.
IP66 / IP67 / IP68 — Dust/water protection levels (66 = dust tight + strong jets; 67 = immersion up to 1m; 68 = continuous immersion).
NEMA 4X — Protection against corrosion, water and dust — common for industrial enclosures.
NEMA 7 / 9 — NEMA classes related to hazardous locations (indoor).
Stainless Steel 316L — Preferred housing material for corrosion resistance in coastal/chemical environments.
Explosion-Proof Camera — camera assembly certified to contain internal ignition and not propagate to atmosphere.
Hazardous Location Camera — general term including explosion-proof, intrinsically safe, purged & pressurized.
PTZ Explosion-Proof Camera — explosion-proof pan/tilt/zoom units for perimeter, tank farms, and process lines.
Dome / Bullet — housing shapes; selection driven by mounting and environmental protections.
IR Explosion Proof Camera — includes IR illuminators; thermal management must meet T-rating.
EX-rated Accessories — junction boxes, PoE injectors, media converters rated for HazLoc.
UL 1203 — UL standard for explosion-proof electrical equipment.
UL Listed / UL Classified / UL Recognized — marks with different scoping.
cFMus / FM Approved — FM Approvals certification for US/Canada industrial equipment.
ATEX Directive 2014/34/EU — EU regulation for equipment in explosive atmospheres.
NEC (NFPA 70) — U.S. electrical code that defines Class/Division and installations.
IEC 60079 series — international technical standards for explosive atmospheres.
IECEx — conformity assessment scheme that complements ATEX for global acceptance.
Ex d (Flameproof / Explosion-Proof) — enclosure contains internal explosion and dissipates flame.
Ex e (Increased Safety) — design reduces chance of sparks and hot surfaces during normal operation.
Ex i (Intrinsic Safety) — limits electrical energy so it cannot cause ignition.
Ex p (Pressurization / Purged) — enclosure kept at positive pressure to exclude hazardous gas/dust.
Ex m (Encapsulation) — components embedded in resin to prevent ignition sources interacting with atmosphere.
Ex o / Ex q / Ex op — other specific protection types (oil immersion, powder filling, optical radiation safety).
Conduit Seals / Cable Glands — prevent gas migration along wiring into safe zones.
Bonding & Grounding — required to avoid static build-up and provide safe fault paths.
Enclosure Integrity — preserve threads, gaskets and flame path to maintain certification.
Certified Installation — must follow NEC/ATEX and manufacturer instructions; improper installation voids certification.
Maintenance Procedures — specific steps for servicing that preserve the rating (many require work in safe areas or isolation).
PoE (Power over Ethernet) — common in industrial camera deployments; ensure EX-rated PoE injectors for HazLoc.
ONVIF — interoperability standard for IP cameras.
H.265 / H.264 — codecs for video compression.
WDR (Wide Dynamic Range) — helps in scenes with strong contrast.
Edge Recording / NVR — storage options; choose explosion-proof housings for on-site recorders in HazLoc.
IR / Thermal — infrared illuminators vs thermal sensors; thermal often used where IR reflection is poor.
Oil & Gas / Refineries — process monitoring, flare stack surveillance, tank farm security.
LNG Facilities — cryogenic considerations + hazardous gas risks.
Chemical Plants — solvent handling and storage require high IP and low T-ratings.
Mining — combustible dust risks, remote deployments.
Grain & Food Processing — dust hazards, ATEX / IECEx considerations.
Aerospace Test Stands — rocket test & engine testing — extreme hazard zones.
Minimum Ignition Energy (MIE) — smallest energy that will ignite a gas/vapor/dust.
Minimum Ignition Temperature — equality relevant to T-rating selection.
Auto-Ignition Temperature — temperature at which a substance ignites without external spark.
Ventilation & Gas Detection — part of safe system design (cameras are part of monitoring, not mitigation).
Explosion Containment vs Mitigation — containment prevents propagation; mitigation reduces risk/severity.
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