Oil rigs can be perilous environments. On January 22, 2018, an explosion on an oil rig in eastern Oklahoma tragically exemplified this danger, resulting in multiple fatalities and injuries. This catastrophic event was caused by an uncontrolled release of gas that ignited.
Preventing such accidents is crucial. Flammable contaminants in the air, such as gas and dust, can lead to explosions. When these substances reach certain concentrations, even a single spark can trigger a devastating explosion.
Hazardous Locations
A hazardous location (HAZLOC) is defined as an area where the atmosphere contains sufficient quantities of flammable or explosive gases, dust, or vapors. Examples of hazardous environments include:
- Oil and gas platforms
- Oil and gas drilling rigs
- Oil tankers
- Refineries and petroleum terminals
- Pipelines
- Military facilities
- Chemical and pharmaceutical factories
- Food processing plants (where ingredients like sugar, starch, flour, spices, tea, grain, and proteins can create explosive dust)
The presence of flammable gases or combustible dust alone does not define a hazardous area. The risk is determined by the quantity or concentration of these substances. For instance, an area with hazardous gas levels for an hour annually is less dangerous than one with hazardous gas levels continuously.
Standards for Rating Explosion Environments
A hazardous area is designated by an Authority Having Jurisdiction (AHJ)—such as a Fire Marshal, risk assessment engineer, occupational safety authority, or insurance underwriter. Once designated, all equipment, including IP cameras, must adhere to protective measures that mitigate explosion risks.
Standards for hazardous areas vary by region but generally use classifications such as CLASS, Division, and Zones. In the USA, the National Electrical Code (NEC) specifies these as “divisions” and “zones”:
- Division 1: An area where ignitable concentrations of flammable gases, vapors, or liquids are likely to be present most of the time (over 10 hours per year) during normal operations.
- Division 2: An area where ignitable concentrations of flammable gases, vapors, or liquids are not likely to be present under normal operating conditions (less than 10 hours per year).
European standards, such as those outlined in UL60079, use “zones” to describe hazard levels more precisely:
- Zone 0: An area where ignitable concentrations of flammable gases, vapors, or liquids are present continuously or for long periods (over 1,000 hours/year) under normal conditions.
- Zone 1: An area where ignitable concentrations of flammable gases, vapors, or liquids are likely to be present between 10 and 1,000 hours per year.
- Zone 2: An area where ignitable concentrations of flammable gases, vapors, or liquids are not likely to be present under normal conditions (less than 1 hour per year).
Explosion-Proof Enclosures and Cameras
Explosion-proof enclosures can house cameras, while explosion-proof camera systems include both the camera and enclosure. It’s generally preferable to purchase a complete system, as UL standards require that cameras be installed in UL-approved facilities. While international and European standards may not have this requirement, it’s essential that the camera used is also approved for explosive environments.
IP Camera System Protection Methods
To ensure an explosion-proof IP camera system is adequately protected, it should have the following features:
- Spark Prevention: The system must prevent sparks from reaching combustible fumes or dust. This includes sealing all entry points for cables.
- Containment: The system should prevent combustible gases and dust from entering the enclosure, often achieved by pressurizing the enclosure with inert gas.
- Ignition Prevention: The camera should not be a source of ignition. This means avoiding batteries that could explode and maintaining safe power levels.
- Durability: In the event of an internal explosion, the enclosure should be robust enough to contain the damage. These enclosures are designed to be stronger than standard camera housings.
Certification Checks
Ensure that all equipment meets the necessary certifications for its environmental conditions. Key certifications include:
- Explosion-Proof Housing: The enclosure and camera should meet certifications indicating explosion-proof housing (Ex d) for potentially explosive environments.
- Dust Ignition Protection: Certification (tD A21) for zones 21 – 22.
- Temperature Control: The enclosure should not exceed 85°C in a dust environment (ATEX: T6), to prevent ignition in a gas environment.
By adhering to these standards and protection methods, the safety and reliability of surveillance systems in hazardous environments can be significantly improved.