Explosion proof cameras for Zone 1 & Zone 2 industrial surveillance

Industrial cameras for hazardous areas fall into two broad categories based on their protection concept:

Flameproof (Ex d) is the dominant protection concept for fixed surveillance cameras. The camera sits inside a heavy machined enclosure designed to contain any internal explosion and cool escaping gases below the ignition temperature of the surrounding atmosphere. Ex d cameras are defined in IEC 60079-1.

Increased safety (Ex e) is sometimes used for camera junction boxes and power supplies, but rarely for the camera enclosure itself. It works by eliminating potential ignition sources (arcs, sparks, excessive temperatures) rather than containing them.

Some camera systems use a combination: an Ex d enclosure for the camera with Ex e terminal boxes for power and data connections. The entire assembly must be covered by a single Ex certificate or a set of certificates that reference each other as associated apparatus.

The protection concept required depends on the hazardous area zone classification at your facility. Zone 1 demands Ex d or Ex ia protection for cameras, while Zone 2 allows less stringent methods such as Ex nA or Ex ec. Most industrial camera manufacturers target Zone 1 certification because a single product can then serve both Zone 1 and Zone 2 installations.

Fixed cameras are mounted in a static position and cover a defined field of view. They are simpler to certify because there are no moving parts inside the Ex d enclosure. Fixed explosion proof cameras are the most common type for process monitoring, perimeter surveillance, and safety documentation in hazardous areas.

PTZ (pan-tilt-zoom) cameras add motorised movement and optical zoom. The motors, gears, and electrical connections for pan/tilt must all be designed to maintain the Ex d integrity of the enclosure. This makes PTZ units significantly more expensive and heavier than fixed cameras. A typical Zone 1 PTZ camera weighs 20–40 kg including the housing.

For Zone 1 applications, PTZ cameras must maintain their flameproof integrity across the full range of motion. The cable management system (slip rings or flexible conduit) is part of the certification. Before specifying a PTZ camera for Zone 1, confirm that the full PTZ range is covered under the Ex certificate — some models restrict tilt angle or continuous rotation speed as a condition of certification.

Ex d housings are certified enclosures that accept standard (non-Ex) IP cameras. The housing provides the explosion protection. This approach offers flexibility: when camera technology improves, you can upgrade the camera module without replacing the (expensive) housing, provided the new camera is listed on the housing's certificate schedule.

Integrated explosion proof cameras combine the camera, lens, and Ex d enclosure as a single certified product. Installation is simpler (one unit, one certificate), and the manufacturer guarantees thermal management and optical performance. The trade-off is that camera upgrades require replacing the entire unit.

When choosing between the two approaches, consider the expected camera lifecycle. If the site will need resolution or analytics upgrades within 5–7 years, a housing-based approach may offer better total cost of ownership. For installations where the camera will remain unchanged for its operating life, integrated units are simpler to procure and support.

Choosing the right explosion proof camera involves more than matching the Ex rating to the zone. Several application-specific factors determine which camera type and vendor will perform best on site:

Network infrastructure. Cameras with Power over Ethernet (PoE) simplify installation by combining power and data in a single cable. However, PoE is limited to approximately 25W (standard PoE) or 60W (PoE++), which may not be sufficient for heated PTZ units in cold environments. Sites without existing Ethernet infrastructure may prefer cameras with fibre optic connections or coaxial options.

Environmental conditions. Offshore platforms and chemical plants expose cameras to salt spray, hydrogen sulphide, and UV radiation. Marine-grade stainless steel (316L) housings resist these conditions better than painted aluminium. For cold climates, verify the camera includes a certified heater element — window fogging or ice formation can render a camera useless without one.

Analytics and integration. Modern explosion proof cameras increasingly support on-edge video analytics — motion detection, line crossing, and flame/smoke detection. These analytics run on the camera processor, reducing bandwidth to the control room. When specifying a camera, confirm that the analytics firmware is included in the Ex certification; aftermarket software modifications to the camera processor could invalidate the certificate.

Maintenance access. Ex d cameras require the enclosure to be opened for lens cleaning and firmware updates. This must be done under a hot work permit or after the area has been gas-freed. Integrated units with wiper systems and remote firmware update capability reduce the frequency of enclosure openings — a significant operational advantage on platforms where gas-freeing is expensive and time-consuming.

Every cable entry into an Ex d camera enclosure must use a certified cable gland that matches the enclosure's thread type and Ex certification. Common thread standards are M20, M25, and ¾" NPT. The cable gland must be listed in the camera's certificate schedule or carry its own compatible Ex d certification.

Unused cable entries must be sealed with certified blanking plugs — not standard pipe fittings. A single uncertified blanking plug compromises the entire enclosure's flameproof integrity.

Mounting brackets and junction boxes are often overlooked in camera installations. If the junction box is within the hazardous area, it must carry its own Ex certification (typically Ex e for terminal boxes). The bracket itself does not require certification but must be designed so that it does not create a hot surface or friction spark hazard — stainless steel or non-sparking alloy brackets are standard practice.

Before installing any explosion proof camera, verify the following against the Ex certificate:

1. Zone and gas group — confirm the camera's Ex d rating matches the site's zone classification and gas group. Most industrial cameras are certified Ex d IIC, covering all gas groups including hydrogen.
2. Temperature class — ensure the camera's T-class is equal to or lower than the auto-ignition temperature of gases present. T6 (85 °C max surface) is the most conservative; T5 (100 °C) and T4 (135 °C) are also common.
3. Ambient temperature range — Ex d cameras have a certified ambient operating range. Operating outside this range (e.g., in direct desert sunlight or arctic conditions) may void the certification. Check for Special Conditions specifying ambient limits.
4. Cable glands and entries — every cable entry into the Ex d enclosure must use a certified cable gland of the correct thread and certification. Unused entries must be sealed with certified blanking plugs.
5. Window and lens — the optical window is part of the Ex d enclosure. Scratched or damaged windows must be replaced with the exact part listed on the certificate. Aftermarket windows are not permitted.

For housing-based systems, verify that the specific camera module installed is listed on the housing's certificate schedule. Installing an unlisted camera — even one with identical physical dimensions — voids the housing's Ex protection.