IEC 61285 pdf download

IEC 61285 pdf download Industrial-process control – Safety of analyser houses
1 scope
This International Standard describes the physical requirements for the safe operation of theprocess analyser measuring system installed in an AH in order to ensure its protection againstfire,explosion and health hazards. This standard extends beyond lEC 60079-16 to includehouses with Zone 2 interiors and to apply to toxic hazards.(Appropriate national guidelines ontoxic hazards are to be followed.)
This standard does not address facilities where dust is the hazard.
Clause 4 addresses the location of the AH and connection within the process plant areas.
Clause 5 addresses the design, construction and layout of the AH. It does not address partsof the analyser measuring system installed in other locations such as sample conditioningrooms (ScR) or switchgear rooms.
Clause 6 addresses measures for reducing the danger of explosion for AHs while permittingmaintenance of equipment with the power on and the case open.
NOTE For most fuids，the major constraint is that the concentration of vapours，which are hazardous forpersonnel, is lower than the lower explosive (flammable) limit (LEL)(see Clause 7).
Using n-Pentane as an example，the LEL is 1,4 % or 14 000 x 10-6.The level immediatelydangerous to life or health (which is the maximum level from which a worker could escapewithin 30 min without any escape-impairing symptoms or any irreversible health effects) isonly 0,5 %or 5 0o0 × 10-6.
Classification of a house interior as Zone 1 may imply that no technician can enter withoutprotective equipment such as breathing gear. Placing an AH in a Zone 1 area would usuallyimply that no technician could approach the house without wearing protective equipment.
Clause 7 addresses those measures for protecting personnel from materials in theatmosphere of AHs that are hazardous to health.
2Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies.For undated references, the latest editionof the referenced document (including any amendments) applies.
IEC 60079-16:1990，Electrical apparatus for explosive gas atmospheres – Part 16: Artificialventilation for the protection of analyser(s) houses
3Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
analyser cabinet
small housing in which analysers are installed individually or grouped together. Maintenance is performed from outside the cabinet with the door(s) open
3.2
analyser shelter
structure with one or more sides open and free from obstruction to the natural passage of air,in which one or more analysers are installed. The maintenance of the analysers is normally performed in the protection of the shelter