We sat down with Bill Richards, VP of Operations at IVC, to discuss explosion-proof cameras and some key considerations when deploying them in hazardous environments.

Interviewer: Hi Bill. In layman’s terms, what is an explosion-proof camera?

Bill: An explosion-proof camera is a specialized type of camera designed to operate safely in environments where there is a risk from explosive gases or dust. These cameras are constructed with rugged and sealed enclosures. Should an explosion of gases occur inside the enclosure, the enclosure will contain the explosion and the surface temperature will remain below a certain threshold. There are many methods to certify a device or enclosure for a hazardous location. Explosion-proof, flame-proof and intrinsically safe denote the most popular for North America and other discrete locations.

Interviewer: What are the different classifications for explosion-proof cameras and how should companies determine the type required for their hazardous environment?

Bill: Explosion-proof cameras are classified into different groups based on the type of hazardous environment they are designed to operate in. In the United States, these classifications are typically defined by the National Electric Code (NEC). The three classes of hazardous locations include Class I for gases, Class II for dust, and Class III for fibers. In addition, per UL standards, there are division requirements. In locations classified as Division 1, hazardous materials are present all the time. In locations classified as Division 2, the hazard exists only in intermittent or upset conditions. For example, the hazard may be present in the atmosphere due to abnormal conditions, such as a leak or a spill. In addition to Class and Division standards, there are also Zone classifications which means the Zone-rated product has been certified against a different standard. For instance, the testing lab FM Approvals has developed its own recognized standard. Within Division/Zone ratings, the certification defines the material type, such as specific gases (e.g. propane), dust (e.g., mining dust), and fibers (e.g. aluminum). These zones indicate the likelihood of the presence of explosive atmospheres. To complicate matters further, Europe and Asia generally require compliance with ATEX, while other countries require compliance with IECEx. Last, there are also country specific standards such as for Japan and Russia.

To determine if an explosion-proof camera is suitable for the hazardous location where it will be deployed, it’s critical to carefully review the camera’s documentation, markings, and certifications.

Interviewer: When assessing explosion-proof cameras, is there anything companies should pay particular attention to?

Bill: An important consideration is the temperature rating of the camera. Known as the “T” rating, it refers to the maximum surface temperature of the equipment during normal operation. The “T” rating is a critical consideration because, should an explosion occur inside the enclosure, you need to be sure the surface temperature of the enclosure will not approach or exceed the ignition temperature of the ambient materials.

Certified cameras have specific ambient temperature ranges, but prudent designs take into account factors like radiant heat, adjacent heat sources, or direct sunlight that can increase internal temperatures. For instance, if an enclosure is rated for 50°C, internal temperatures, influenced by waste heat from electrical components, may exceed this. To safeguard electronics, a 50°C-rated enclosure might be engineered to handle 60°-65°C. This is not a requirement of the certification process but is simply smart engineering.

Interviewer: What should companies keep in mind when getting ready to install explosion-proof cameras?

Bill: First, it’s important to hire a knowledgeable installer. In North America, the installation of devices in hazardous locations is governed by NFPA 70e. So, it’s highly recommended that the installation is performed by a technician familiar with the requirements of this standard.

Second, sometimes we see customers try to service the camera assemblies themselves and accidentally damage the equipment. This can be a big problem. When customers service their own camera assemblies, it will generally void the explosion-proof certifications.

Interviewer: What are some common installation challenges that you see in the field?

Bill: From a mechanical standpoint, the enclosure must be firmly secured to its intended foundation. There is often vibration present so mechanical fasteners must be locked in place. Additionally, a safety lanyard is required should the device come free. For agile (pan-tilt-zoom) cameras, the installation must ensure freedom of movement in all intended directions.

Interviewer: Can you tell us a little about IVC’s line of explosion-proof cameras?

Bill: IVC primarily manufactures complete assemblies — which include both the camera and the enclosure. The assemblies are certified for a specific set of components or, in certain cases, limited to a particular power draw of the internal components. This factor influences the camera’s rating. We offer a range of assemblies, including Class I, Class II, ATEX and IECEx configurations in both pan-tilt-zoom and fixed models, along with accessories like junction boxes. It’s important to emphasize that IVC provides certified assemblies. Opting for an off-the-shelf empty certified enclosure can be risky unless you’re aware of the approval parameters, including power consumption, internal volume, and the cross-sectional area of components. If these exceed certain limits, an internal explosion might cause the enclosure to surpass the “T” rating or expected temperature rise, potentially leading to an ignitable situation.

Interviewer: What kind of quality testing does IVC conduct with its cameras?

Bill: All IVC rated products are certified by a Nationally Recognized Testing Laboratory (NRTL). This process includes numerous tests including a temperature rise test to check the camera’s surface temperature during normal use, an ignition test to assess a camera’s resistance to causing ignition in explosive atmospheres, and an impact test to evaluate the camera’s ability to withstand physical impact in hazardous environments. Certification is a long and expensive process. Once a product is certified, IVC is audited every quarter by an appointee of the NRTL to ensure compliance with the product parameters as originally tested.

The manufacturing tolerances for rated devices are very tight. Any joints, also called flame paths, must have minimal clearance between parts. IVC physically inspects each of the critical components before assembly. There are numerous quality control checks on sub-assemblies throughout the process.

We also perform final quality testing on all our products and ensure that they are built to comply with multiple documents, such as the Bill of Materials and the Build Manual. IVC also performs burn-in tests on all rated assemblies with intermediate inspection tests conducted throughout the process.

Thanks Bill.

About Bill Richards: Bill Richards is the co-founder and Vice President of Operations at Industrial Video & Control. He leads the company’s hardware engineering efforts and has over 20 years of experience developing products for hazardous areas. Bill holds a bachelor’s degree in engineering from the University of Michigan.