Outdoor equipment enclosures

A high capacity, easy-access enclosure from Intertec provides plant engineers with a versatile alternative to free-standing cabinets for the environmental protection of field-based process instrumentation. Developed at the request of a Russian oil refinery, the enclosures are made from tough glass reinforced polyester (GRP) and include highly insulated options for use in extremely cold climates. They also offer more space than typical instrument enclosures, to allow plant personnel to use gloved hands when accessing the equipment. Typical applications include housing differential pressure flowmeters and process transmitters in refineries, petrochemical and chemical processing plants.

The Diabox 277 enclosure measures 600 x 750 x 600 mm (HxWxD) and has an internal volume of approximately 277 litres, depending on the level of insulation specified. Manufactured from a high-performance grade of GRP using a hot-press moulding process, the standard versions of the enclosure provide an exceptionally robust and rigid housing; they have a wall thickness of 6mm yet typically only weigh 18kg. This combination of rigidity and low weight means that the enclosures can be mounted on small-footprint pipe stands or clamped directly to process pipes, making them ideal for protecting instruments in locations where free-standing cabinets would be impractical due to the amount of ground space they require.

For applications that require protection against extremely cold conditions, Intertec produces an ‘arctic’ version of Diabox 277 that is suitable for use in temperatures as low as minus 60 degrees Celsius. This enclosure is manufactured from a proprietary composite ‘sandwich’ material, comprising inner and outer walls of GRP enclosing a closed-cell polyurethane (PU) foam core. The inner GRP wall provides a smooth, easy-to-clean finish. It also protects the foam against accidental physical damage, such as might be caused during equipment installation, routine maintenance or cleaning, thereby maintaining the enclosure’s thermal integrity and performance.

Despite its large size, the Diabox 277 has a very low heat transfer coefficient of 13 W/K, which minimises the power rating and operational cost of any freeze protection, anti-condensation, or temperature regulation heating that may be fitted. In the case of the ‘arctic’ version of the enclosure, its GRP-PU foam-GRP walls provide uniform and near-perfect insulation, resulting in an exceptionally low heat transfer coefficient of just 2.4 W/K.