Mobile Ex p Enclosures

A Zone 2 certified mobile, plug and play, Ex p enclosure 

Application

While fixed electrical control panels are a common feature in hazardous areas, some equipment, especially mobile service equipment, requires a special solution. This application note describes a project to adapt a portable oil cleaning system and develop a mobile, plug-and-play, purged and pressurised enclosure for use in Hazardous Areas ATEX/IECEx Zone 2.

Expo Solution

To enable an Ex p solution, the oil cleaning system is installed inside a custom designed moveable IP66 enclosure. The enclosure is designed in such a way as to give access for moving the machine in and out, as well as maintenance access to key components.

Although intended for use in a Zone 2 environment, the Expo enclosure is fitted with both an X-purge (Size 1) and MIU (dX) to provide improved operational security, especially in unmanned locations. 

Challenges and design considerations included:

• Temperature – due to the presence of hot oil, it was necessary to add thermal insulation around the purification chamber. Additionally, a size 1 vortex cooler was fitted to provide cooling if required.
• Some modifications were necessary to ensure closed volumes, such as the control box & transformer housing, were ventilated and able to be purged.
• The motor fan was assessed to ensure it did not cause atmospheric ingress around nearby door seals.
• Safety devices included thermostats for over-temperature shut off and a float switch to detect any oil overflow within the enclosure
• The oil was not flammable within the normal operating parameters, so the was no Internal Source of Release to be considered.

Typical system

Hazardous Area Considerations

• This specific project had the following requirements. However, the application could be extended to Zone 1, Class I Div 1.

• ATEX/IECEx: Zone 2 Gas group IIC
• NEC500: Class I, Div 2 Gas groups B,C,D
• T4 (135°C)
• Tamb -20 to +55°C

What Expo Needs to Know

• Equipment dimensions
• Power requirements
• External control signals / data lines
• Thermal characteristics
• Accessibility to operate
• Accessibility for servicing
• Plug-and-play utility requirements