Installation and maintenance challenges of NEMA Type 7 hazardous area enclosures

National Electrical Manufacturers Association (NEMA) Type 7 explosion-proof enclosures are widely regarded for their robust construction and dependable operation. These enclosures are sustained without the additional safety systems required to ensure operation of a purged and pressurized piece of equipment. Similarly, NEMA Type 7 enclosures are maintained without the costly component inventory which may be required to ensure maximum uptime of non-serviceable encapsulated equipment. NEMA Type 7 enclosures are generally constructed of cast aluminum or iron-based materials and are capable of withstanding numerous explosive events. NEMA Type 7 enclosures ensure hazardous area safety by extinguishing the flame through precision machined surfaces and controlling structural deformation should an explosive event occur. If maintenance practices are not designed to ensure the integrity of the enclosure, repeated access to internal equipment and oxidation of critical surfaces may lead to the loss of the enclosure's explosion-proof protection. The paper reviews maintenance best practices and common errors with their potential consequences. The likelihood of error may be reduced by employing a variety of available technologies. Each technology will be explained based on case study examples to illustrate the reduction in total cost of ownership for equipment when best practices are observed.