IEC 60079-13:2017 gives requirements for the design, construction, assessment, verification and marking of rooms used to protect internal equipment:
– located in a Zone 1 or Zone 2 or Zone 21 or Zone 22 explosive atmosphere without an internal source of gas/vapour release and protected by pressurization;
– located in a Zone 2 explosive atmosphere with or without an internal source of gas/vapour release and protected by artificial ventilation;
– located in a non-hazardous area, containing an internal source of gas/vapour release and protected by artificial ventilation;
– located in a Zone 1 or Zone 2 or Zone 21 or Zone 22 explosive atmosphere containing an internal source of gas/vapour release and protected by both pressurization and artificial ventilation.
The term "room" used in this document includes single rooms, multiple rooms, a complete building or a room contained within a building. A room is intended to facilitate the entry of personnel and includes inlet and outlet ducts. An acoustic hood and other like enclosures designed to permit the entry of personnel can be considered as a room.
This document also includes requirements related safety devices and controls necessary to ensure that artificial ventilation, purging and pressurization is established and maintained.
A room assembled or constructed on site, can be either on land or off-shore. The room is primarily intended for installation by an end-user but could be constructed and assessed at a manufacturer’s facility, where the final construction such as ducting can be completed on site.
This document does not specify the methods that may be required to ensure adequate air quality for personnel with regard to toxicity and temperature within the room. National or other regulations and requirements may  exist to ensure the safety of personnel in this regard.
This second edition cancels and replaces the first edition published in 2010. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) modification of the title of this document to include artificially ventilated room "v" in addition to pressurized room "p";
b) addition of types of protection "pb", "pc", and "vc" and removal of types of protection "px", "py", "pz" and "pv";
c) definition of the differences between pressurization and artificial ventilation types of protection;
d) removal of protection of rooms with an inert gas or a flammable gas from the scope of this document;
e) addition of an informative annex to include examples of applications where types of protection pressurization or artificial ventilation or pressurization and artificial ventilation can be used and associated guidelines.
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1. Basic frame
The base frame consists of two (2) lower side rails, several cross members and a gooseneck tunnel, which are welded together as a subassembly.
 
2.Front End
The front end will be composed of corrugated end wall and front end frame,
which are welded together as a sub-assembly.    
 
3. Rear End 
Rear end is composed of Rear End Frame which consists of one door sill, two
corner posts, one rear header with header plate and four corner fittings, which
are welded together as a sub-assembly, and Door Systems with locking
devices.
 
4.Side Wall Assembly
Side Walls Each side wall will be composed of a number of sheets for the intermediate (inner) parts and outer panels at each end of side wall, fully vertically corrugated into trapezium section, butt welded together to form one panel by automatic welding. 
 
5.Roof
The roof will be constructed by several die-stamp corrugated steel sheets with a certain upwards camber at the center of each trough and corrugation, these sheets are butt jointed together to form one panel by automatic welding. 
 
 



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A hazardous area can be defined as any location where there is risk of an explosion. But every hazardous area is different and each has specific requirements depending on the nature of the atmosphere and the elements that are present.
Fundamentally, for an explosion to take place, flammable or explosive gases, vapours, mists or dusts will be present. Then, the level of risk of an explosion is based on the frequency and duration of the occurrence of an explosive atmosphere. This level of risk is represented by classifying the hazardous area as Zone 0, Zone 1 or Zone 2 (for gas, vapour and mist atmospheres) or Zone 21 or Zone 22 for dust atmospheres.
we will look at what defines Zone 0, Zone 1 and Zone 2 hazardous area classifications and the considerations for specifying lighting into each area. But first, we must consider what is likely to cause an explosion in the first place.
There are three necessary components for an explosion to occur;
1. Flammable Substance – this needs to be present in a relatively high quantity to produce an explosive mixture (e.g. gas, vapours, mists and dusts).
2. Oxygen – oxygen is required in high quantities and in combination with the flammable substance to produce an explosive atmosphere.
3. Ignition Source – a spark or high heat must also be present.

Where there is potential for an explosive atmosphere, special precautions are needed to prevent fires and explosions. Electronic equipment, including lighting, needs to be purpose designed for use in hazardous areas to prevent a spark occurring and igniting any flammable substances.
Although every application is different, for the ease of monitoring and specification each hazardous area is classified as a particular level or “zone”. As a result, all hazardous area equipment must be designed with hazardous area zone classifications in mind, as the “zone” governs the level of protection and precaution required. It is essential to know which zone you are working in, so that you can specify the most appropriate equipment.
For gases, vapours and mists the zone classifications are recognised as Zone 0, Zone 1 and Zone 2 areas. Let’s take a look at what defines each zone…
  1. Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur.
  2. Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. It may exist because of repair, maintenance operations, or leakage.
  3. Zone 2 is a place in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. These areas only become hazardous in case of an accident or some unusual operating condition.