Hazardous Area Surveillance / Explosion 'Proof' CamerasAuthor: Brian Rhodes, Published on Feb 16, 2012
Placing surveillance cameras in hazardous (highly flammable) environments have far more demanding requirements than typical surveillance use. Liability risks are much higher and the cost of equipment that meets this requirement can be dramatically more expensive. In this note, we discuss these requirements, how they are determined, and the different options available for satisfying them.
How do I know when to consider special rated equipment?
If you are an integrator, security manager, IT manager or manufacturer, you almost never should be deciding yourself whether or not special rated equipment is required.
Typically, the 'AHJ' - 'authority having jurisdiction' - makes this determination. The AHJ might be a Fire Marshal, an operational risk assessment engineer, occupational safety authority, or an insurance underwriter. That individual will classify the hazardous area based on risk criteria. It is with the best interest of the owner/operator of such an environment to realize, control, and mitigate any potential risks in the hazardous area – including the installation of electronics equipment like surveillance cameras. The provider may be asked to provide appropriate certification of the furnished equipment.
In any case, it is important to base equipment specifications upon a valid assessment, as the cost of equipment certified as ‘safe for use’, or ‘intrinsically safe’, is significantly more expensive than non-certified equipment.
What does a particular 'hazard rating' mean?
Worldwide, a variety of hazardous area certification marks exist, and it is appropriate to furnish equipment that satisfies whichever prevailing standard applies to your application.
In the US, the widely adopted "National Electrical Code or 'NEC', defines environments by flammable volatility. The classification is segmented in three (3) classes, with a Class 1 environment being the most volatile typically including sites that handle gasoline and chemicals. An accompanying clarifier (the Division) denotes the default danger ‘type of condition’, being Division 1 – normal, or Division 2 – abnormal.
In this manner, the risk of fire or explosion in a hazardous location can be qualified. For example, portions of a fuels transfer facility may be designated as a ‘Class1/Division1’ area, while a wood pulp storage facility may be designated as a ‘Class3/Division2’ facility. Both classifications denote some risk, but certainly the risk is qualified as being more significant in the area with the lower rating.
For readers who want to learn more about what sites are typically classified as Class 1 vs 2 and 3, review this US government explanation of hazardous types.
In the EU, a rough equivalent for the NEC’s Class/Division rating is noted by the ‘ATEX directives, 95/137’. While technical definitions of hazardous areas differ (and may not overlap) among standards, the ATEX directive seeks to quantify hazardous areas in the same manner.
In South America, especially Brazil, the INMETRO risk classification system performs the same function as the bodies listed above.
While independent of each other, these ratings all seek to explicitly define hazardous areas.
What equipment satisfies this requirement?
Hazardous environments require specially rated electronics/electrical equipment that are certified to not precipitate ignition or cause ignition to spread to the surrounding environment.
There are two types or categories of equipment to choose from:
- 3rd party rated enclosure + 'regular' COTS camera
- Assembly/kit that pre-fabricates hazardous enclosure and camera
Examples of 3rd party 'explosion proof' or 'intrinsically safe' housings include:
The cost range for rated enclosures ranges is $900 - $1,700 USD.
The second category is a singular rated ‘assembly’ – camera, housing, enclosure, cabling – that has been previously certified as a unit. No changes, beyond positioning the equipment, are allowed to be made during install for the assembly to retain this rating. Examples of 'intrinsically safe' assemblies include:
- Videolarm/MOOG’s ‘PurgeDome’ (Class1/Div2)
- Pelco’s ExSite Camera Series
- IVCCO’s variety of ATAX and Class/Div rated Cameras
The cost range for rated assemblies is $8,000 - $14,000 USD.
Choosing Between these Categories
This is a hard decision as important tradeoffs exist.
The advantages of using 3rd party enclosures include:
- Low Price: It will almost always be significantly cheaper to buy a 3rd party rated enclosure and COTS camera rather than an assembly.
- Camera Selection: This allows freedom to pick your preferred camera
- VMS Compatibility: This makes it easier to guarantee interoperability with VMS
However, there is a crucial disadvantage of using 3rd party enclosures:
- The burden falls to the provider to ensure that all of the accompanying portions of equipment are also certified. A significant amount of risk is accepted by the integrator when supplying a 'piecemeal' solution.
Supplying a rated 'assembly' might ultimately prove to be a better decision depending upon how stringently the requirements are interpreted, and how willing the supplier is to accept risk for nonconforming performance of a 'piecemeal' assembly. A rated assembly that is installed properly serves to indemnify the supplier of risk.
Whichever option you choose, make sure the AHJ signs off in writing beforehand.
What alternatives do I have rather than placing this type of equipment?
You can try to avoid this type of equipment.
Rated equipment is much more costly. While $800 USD might cover an outdoor ready box camera in weatherized housing, furnishing and maintaining a certified solution can be 5 to 10 times more expensive.
Additionally, maintaining rated equipment can be more costly. This equipment often requires positive pressure environment is maintained in the sealed housing, and an inert gas (such as Nitrogen) renders the interior environment void of combustible Oxygen. This aspect of the camera must be maintained over time
Because of the significant increase in cost, locating standard equipment outside of the hazardous area is a common alternative. Even if this strategy results in requiring more (remotely located) standard cameras, they often can be added in combinations that still fall beneath the cost of a single rated camera.
Related Reports on Tutorials
Most Recent Industry Reports
The world's leading video surveillance information source, IPVM provides the best reporting, testing and training for 10,000+ members globally. Dedicated to independent and objective information, we uniquely refuse any and all advertisements, sponsorship and consulting from manufacturers.