Chemical storage and solvent handling areas are classified Class I, Division 1 at the immediate vicinity of tank connections, loading arms, and pump seals, and Division 2 in surrounding areas with adequate ventilation. Gas group depends on the specific chemical — Group D for most hydrocarbons and common solvents, Group C for ethylene and cyclopentane, Group B for hydrogen-containing streams. Housing material depends on the corrosivity of the specific chemicals handled.
Chemical plants and solvent storage facilities handle a wider range of hazardous materials than oil and gas refineries, which means the hazardous area classification, gas group, and material selection for explosion-proof cameras varies significantly by site. A camera that is correctly certified for a propane-butane storage area may not be suitable for an ethylene oxide or hydrogen cyanide storage area without additional review. This guide covers the classification process, gas group selection, housing material requirements, and placement strategy for chemical storage and solvent handling surveillance.
Common Chemical Storage Areas and Their NEC Classifications
| Chemical / Area | NEC Group | Typical Classification | Notes |
|---|---|---|---|
| Propane, butane, LPG | Group D | Div 1 at loading; Div 2 general | Most common; Group D cameras standard |
| Gasoline, toluene, xylene | Group D | Div 1 at tank connections; Div 2 surrounding | Flammable storage tanks per NFPA 30 |
| Acetone, ethanol, MEK | Group D | Div 1 inside drum handling; Div 2 outside | Common in pharmaceutical and paint mfg |
| Ethylene, cyclopentane | Group C | Div 1 at compressor / transfer | Requires Group C or C&D camera |
| Diethyl ether | Group C | Div 1 throughout handling area | Very low flash point (-45°C) |
| Ethylene oxide (EO) | Group B | Div 1 throughout EO area | Requires Group B (IIC) camera |
| Hydrogen (generation, storage) | Group B | Div 1 at generation / storage | Requires Group B (IIC) camera |
Housing Material Selection for Chemical Environments
Standard aluminum explosion-proof housings are suitable for most hydrocarbon storage and Group D solvent environments. However, several classes of chemicals attack aluminum or require stainless steel: Chlorinated solvents (methylene chloride, trichloroethylene, carbon tetrachloride) cause pitting corrosion in aluminum. Specify 316L stainless steel housings. Strong acids (sulfuric acid, hydrochloric acid, nitric acid) attack both aluminum and standard carbon steel. Use 316L SS with fluoropolymer-coated or non-metallic mounting hardware. Strong caustics (sodium hydroxide, potassium hydroxide) attack aluminum over time. Use 316L SS. Halogenated compounds in the vapor phase can cause surface corrosion of aluminum over extended exposure. For long-term outdoor camera installations at facilities handling these materials, stainless steel is the lower-maintenance choice.
Tank Farm Surveillance: Fixed Cameras vs. PTZ
Fixed-roof tank farms present a coverage challenge: the area between tanks is a classified zone, but cameras positioned on tank rooftops or elevated structures can cover multiple tanks from above the zone boundary. This allows standard industrial cameras (non-explosion-proof) to monitor large tank farm areas from safe-area positions, reserving explosion-proof cameras for positions that must be inside the classified zone — specifically, loading arm areas, pump manifolds, and emergency venting equipment.
For facilities with floating-roof tanks, position cameras to monitor the annular seal area (where floating roof meets tank wall — a common location for VOC emissions and potential ignition sources) as well as gauger walkways and access ladders. PTZ cameras on elevated structures outside the classification boundary can cover multiple tank tops and access routes in a medium-sized tank farm, reducing the total number of explosion-proof fixed cameras required. For guidance on how many cameras are needed for various tank farm layouts, see our explosion-proof camera coverage planning guide.
Loading and Unloading Area Requirements
Chemical truck and railcar loading areas are among the most frequently classified zones in chemical storage facilities. The area within 3 feet of loading arm connections, and within 10 feet of tank car dome openings, is typically Class I, Division 1 when the loading operation is in progress. Cameras at these positions must be rated for Division 1 and the appropriate gas group for the materials loaded.
Loading area cameras serve both safety and security functions: monitoring for product spills during transfer, confirming that safe loading procedures are followed (grounding cables connected, overfill protection active), and recording the loading event for inventory and liability purposes. Position cameras to cover the loading arm connection, the truck or railcar top, and the operator’s position. For the loading area classification boundaries, refer to NFPA 30 Section 6.3 and the facility’s area classification study.
Frequently Asked Questions
What gas group for most solvent storage tanks?
Group D (NEC) or IIA (IEC) covers most solvents: acetone, toluene, xylene, gasoline, ethanol, MEK. Group C for ethylene and diethyl ether. Group B for ethylene oxide and hydrogen.
Do I need explosion-proof cameras throughout the tank farm?
Not necessarily. Many tank farm interiors are Division 2, and cameras outside the classification zone on elevated structures can cover multiple tanks. Division 1 cameras are needed at loading arms, pump areas, and valve manifolds.
What housing for a chlorinated solvent area?
Stainless steel 316L — chlorinated solvents cause pitting corrosion in aluminum. All hardware including mounting bolts should also be stainless or non-metallic.
Is Group D sufficient for a typical chemical plant?
Group D covers most hydrocarbon and common solvent hazards. Verify the specific chemical SDS for facilities handling ethylene, ethylene oxide, or hydrogen, which require Group C or Group B.
How far does the classified zone extend from a storage tank?
Per NFPA 30, typically 3 feet from vents/fill openings is Division 1; 10 feet horizontally and 3 feet vertically from these points is Division 2. Use the facility’s area classification drawing as the primary reference.
Veilux explosion-proof cameras are available in aluminum and 316L stainless steel housings certified for Group C&D (IIA/IIB) in Zone 1 / Class I Division 1. Contact our team with your chemical list and classification drawing for a camera specification tailored to your storage area.
Key Industry Standards and References
Chemical storage area classification follows NFPA 30 (Flammable and Combustible Liquids Code) and NFPA 70 (NEC). Hazard communication for solvents: OSHA HazCom Standard. Area classification methodology: IEC 60079-10-1.
Related Resources
- Browse Explosion-Proof Cameras for Hazardous Locations
- Explosion-Proof Cameras for Chemical Plants
- Explosion-Proof Cameras for Oil and Gas Refineries
- Explosion-Proof Camera Housing Selection Guide
- Request a Project Quote
Need explosion-proof cameras for your facility?
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About the Author
Daniel Fernandez
Daniel Fernandez is a hazardous area security systems specialist with over a decade of experience specifying ATEX, IECEx, UL Class I Division 1, and cUL certified surveillance equipment for oil and gas, chemical, mining, pharmaceutical, and offshore environments. He holds expertise in NEC and IEC area classification standards and has consulted on explosion-proof camera system designs across North America, Europe, and the Middle East.