Application area
Intertec specializes in outdoor enclosures, a large proportion of which are custom designed and supplied fully assembled and tested, ready to hook up to the process.
Source: Intertec
When designing or configuring enclosure protection for sensitive field-based equipment, it pays to consider the entire system—including the enclosure material, its insulation and heat transfer characteristics—rather than focusing simply on specifying appropriate heating (and/or cooling).
Treating the design problem as an inter-related system yields significant benefits for outdoor enclosure applications, especially in harsh environments. For example, a holistic approach has particular benefits in avoiding the 'cold-spots' that can quickly lead to problems from condensation. Plus, it delivers much more stable and controllable operating environments for instrumentation, which can be important in many process control applications, such as process analyzers.
Insulation is key
Specifying an enclosure for sensitive field-based control and instrumentation equipment is not a trivial task. Good insulation is critical to almost all outdoor equipment protection applications. If the enclosure is destined for an environment with extreme conditions, such as a desert or an Arctic region, starting the configuration process with one of the common styles of metal enclosures used for electrical panel gear is usually not such a good solution, and can pose problems for the inexperienced.
The majority of metal enclosures are used inside buildings and the biggest thermal protection problems that most users face is working out how to dissipate heat to the exterior, which itself is usually an environment with a relatively stable temperature such as a factory building.
Greater care is required when the environmental conditions are more challenging, involving protection against frost and condensation, extreme cold or heat or requiring temperature regulation.
Few off-the-shelf metal enclosures are available with the appropriate degree of insulation to minimize the temperature regulation problem. In any event, just adding insulation is rarely adequate, because of fundamental limitations posed by the basic metal construction. Any metal connection between outer and inner shell provides a thermal short-cut. With metal construction, it is almost impossible to avoid metal parts in some design elements (such as the door frame, door leaf, window, wall penetrations for cables and tubing etc) because the stability of this type of housing is based on bent sheet metal, and insulation materials are typically soft. Heat losses are exacerbated by the good heat-conducting properties of a metal enclosure, and often by the typical kind of metal bulkhead fittings used to mount such enclosures as well, which can act as a kind of rudimentary fin.
Moreover, designers almost invariably need to customize enclosures by cutting access holes, changing heat loss characteristics substantially. Holes act as thermal short-cuts and can account for a large percentage of an enclosure’s heat losses.