IEC 60079-16:1990 pdf Electrical apparatus for explosive gas atmospheres Part 16: Artificial ventilation for the protection of analyzer( s) houses

IEC 60079-16:1990 pdf Electrical apparatus for explosive gas atmospheres Part 16: Artificial ventilation for the protection of analyzer( s) houses
1 . Scope
1 .1 This report provides th e general principles of protection, by artificial ventilation, of analyzer(s) houses against th e explosion hazards caused by internal release of flammable substances and, if applicable, against th e hazards caused by an external explosive gas atmosphere. It also gives th e conditions in which electrical apparatus liable to cause ignition may be used in these analyzer(s) houses.
These analyzer(s) houses may be situated in a hazardous area o r in a non-hazardous area.
1 .2 This report contains recommendations for the construction and Oper-ation of analyzer(s) houses, fo r th eir associated installations, such as ai r ducts, and for th e auxiliary devices necessary for providing and maintaining th e conditions for ventilation and, when required,
pressure.
This report also specifies th e verification and testing necessary to prove that the installation conforms to the above recommendations, and the markings to be placed on such rooms or buildings.
Notes 1 . – In certain circumstances, the recommendations may be used for other buildings containing similar sources of release.
2.- This report does not deal with dangers as sociated with the to xicity of gases and vapours which may be dealt with by similar techniques. It does no t deal with requirements not
re l ate d t o exp lo sion s a fe t y .
2. Definitions
For th e purpose of th i s report th e following definitions apply:
2.1 Analyzer(s) house
Aspecific closed room or building containing one o r more analyzers for samples of flammable fluids which are or may be connected to a process installation together with electrical equipment and auxiliary devices.
Note.- A nalyticallaborato ries are not covered.
2.2 Artificial ventilation
A method of mechanical movement of air to reduce and maintain at a safe level the concentration of flammable gases or vapours in the analyzer(s) house. Such ventilation may also be used to maintain the pressure inside the analyzer(s) house above or below the external ambient pressure.
2.3 Ventilation system
The complete installation required to p roduce artificial ventilation.
2.4 Forced ventilation
Artificial ventilation used to force air into the analyzer(s) house.
2.5 Induced lexhaust} ventilation
Artificial ventilation used to extract air from the analyzer(s) house.
2.6 Ventilation failure
A situation wherein the required air flow and, if necessary, the required pressure cannot be maintained.
2.7 Purging
The operation of passing a quantity of air through the analyzer(s) house and its associated ducts in order to reduce any concentration of flammable gas or vapour within them to a safe level.
2.8 Alarm
A signal, which may be audible or visible or both, to warn that appropriate action is necessary.
3. General considerations
3.1 Ceneral safety considerations
The general safety considerations are:
1) to keep the quantity of flammable materials in the analyzer(s) house to the minimum compatible with the normal operation of the equipment installed in the house;
2) to provide an efficient ventilation system to dilute to a safe level any internal release of flammable gas or vapour;
3) to provide measures of protection which take into account venti- lation failure;
4) to provide for the safe disposal of samples.
3.2 Requirements for the analyzer(s) house
(s) house should preferably be a separate building.
However, it may sometimes be necessary to incorporate the analyzer(s) house in an existing building. In such cases the analyzer(s) house should be completely isolated from other parts of the building except as permitted in Sub-clause 5.3. However, air- locks with app ropriate safety provisions may be permitted between the analyzer(s) house and the remainder of the building if the requirements of Sub-clause 5.3 are met. For examples of arrangements see Appendix A.