Pressurisation testing

Pressurised enclosure tests determine if the pressurised enclosure of the electrical equipment can stop explosive gases or dusts from entering and mixing with live parts or hot surfaces.

The design requirements for electrical equipment using pressurised enclosures are specified in International Standards IEC 60079-2 and Australian/New Zealand Standard AS/NZS 60079.2.

The difference in behaviour of potentially-explosive gases (Groups I & II) and dusts (Group III) is recognised in the Standard and certification may either include equipment for one or both types of explosive atmospheres. Test and assessment includes the same detailed approach as used for all explosion-protection techniques.

There are three protection types of pressurisation:

  • 'pxb' applies to Group I & Group II, Zones 1 or 2
  • 'pyb' applies to Group I & Group II, Zone 2
  • 'pzc' applies to Group II & Group III, Zone 2

Pressurisation may be applied to individual enclosures containing electrical control equipment or to single motors.

A control room is another example that may house a variety of electrical equipment (which is not easily protected in any other way). The control rooms may be located within a hazardous area and fresh air is required to be supplied continuously both for the equipment and the personnel who need to check on the controls.

Inert gas is another way of supplying an individual enclosure, particularly where there is little or no leakage of the protective gas.

See our checklist for more information before applying for certification.

Book your test by filling out an application form.