Installers have a number of decisions to make when choosing and installing equipment for hazardous areas. They must have a definition of the area the equipment is installed in and an understanding of the different classifications, zones, temperature classes, and gas groups to allow them to select equipment that is certified safe for use in these areas. They also need to take into account the environment and operating conditions for the equipment.
The following is a brief summary of some of the terms used, although BS 5345 should be referred to for fuller detail.
According to the nature and likelihood of gases present, hazardous areas are classified into zones, gas groups and temperature. Area assessment classifications are carried out by companies using flammable materials in accordance with national standards (BS 5345: Part 2) or industry codes.
The most common zones that an installer would need to select equipment for would be Zones 1 and 2. Zone 1 is defined as an area where an explosive gas atmosphere is present occasionally. Zone 2 is defined as an area where an explosive gas atmosphere is rarely present and only then for a short period of time. Manufacturers will define equipment as suitable for either Zone 1 or Zone 2 (it should be noted that Zone 1 equipment may be installed in either Zone 1 or 2).
Further consideration should be given to gas groups and temperature classifications when specified.
Once the classification issues have been addressed there are further decisions to be made. Due to the nature of the equipment it is often installed in harsh environments and other considerations should be taken into account. If the equipment is to be installed outside, particular attention should be paid to the ingress protection of the equipment. Manufacturers of light fittings have addressed this issue and CEAG has had its 92 series fluorescent fittings certified by ERA as passing its independent deluge test.
Installation time may also be a consideration. An example of this would be a small junction box, where the cost of installing the box may be greater than the cost of the box itself. Manufacturers have long since included integral earth continuity plates to allow earth connections to be made more easily. A range of junction boxes, isolators and motor starters is now available that may be clipped onto a channel/pipe mounting back plate, eliminating any drilling of fixing holes.
Many products are becoming available that are designed for ease of installation. Lighting fittings now have much better access to connection terminals to speed up installation. Often terminal boxes and distribution boards will be supplied with removable gland plates to allow additional entries to be added on site, rather than requiring costly re-working.
It may also be a consideration when selecting equipment to consider the operation and maintenance of equipment over its expected lifetime. There are hazardous area distribution boards on the market that are manufactured from grp with hinged access flaps to allow the mcbs to be re-set without removal of covers or mechanical toggles through the lids of alternative designs of metal enclosures. There are also emergency light fittings now available, such as "intelligent" fluorescent fittings, that will give a visual indication, via leds, of the status of the battery, eliminating the need for time consuming duration tests.
These examples are some of the decisions installers have to make when selecting hazardous area equipment. This clearly shows that once a decision has been made as to the safety considerations there are still many options for selecting various product designs that can offer savings at both installation and over the lifetime of the equipment.
Source
Electrical and Mechanical Contractor
Postscript
Kevin Morris is commercial manager with CEAG-Crouse Hinds.
