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 the process analyser measuring system installed in an analyser house (AH) in order to ensure its protection against fire, explosion and health hazards. This standard applies for analyser houses with inner and/or external potential explosive atmospheres and it applies to hazards caused by toxic substances or asphyxiant gases. (Refer to national guidelines on toxic hazards.) This standard does not address facilities where solids (dust, powder, fibres) are the hazard. This standard does not seek to address all functional safety issues related to analyser houses. 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 parts of the analyser measuring system installed in other locations such as sample conditioning rooms (SCR) or switchgear rooms. Clause 6 addresses measures for reducing the danger of explosion for AHs while permitting maintenance of equipment with the power on and the case open. For most fluids, the major constraint is that the concentration of vapours, which are toxic for personnel, is lower than the lower explosive (flammable) limit (LEL) (see Clause 7). Using n-Pentane as an example, the LEL is 1 ,4 % or 1 4 000 × 1 0 –6 , the level immediately dangerous to life or health (which is the maximum level from which a worker could escape within 30 min without any escape-impairing symptoms or any irreversible health effects) is only 0,5 % or 5 000 × 1 0 – 6 . Clause 7 addresses those measures for protecting personnel from materials in the atmosphere of AHs that are hazardous to health.
3 Terms 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 Note 1 to entry: 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 Note 1 to entry: The maintenance of the analysers is normally performed in the protection of the shelter. 3.3 analyser house AH enclosed building or part of a building containing process analysers and associated equipment where streams for analysis are brought in and which is regularly entered by authorized personnel Note 1 to entry: An AH is not a permanent workplace. Within the scope of this standard, the term AH is used regardless of the structure configuration as either a room, a walk-in cabinet, an analyser container or an analyser building and whether or not it is an integral part of, or attached to, another structure. 3.4 sample conditioning room SCR room that is separated from the AH and has modules for sample conditioning, auxiliary material, or sample disposal equipment 3.5 infrastructure required means and supply with auxiliaries to operate an AH with all equipment therein, for example, instrument air, nitrogen, water, power supply, incidental disposal of waste and disposal of substances introduced to be analysed Note 1 to entry: The infrastructure occasionally comprises the fundament of an AH, the positioning of gas bottles and containers for gas supply and test gases. The infrastructure comprises in addition the ventilation and climatisation of the AH and the needed alarm devices within and outside of the AH. 3.6 maintenance servicing, inspection, repair, improvement and weakness analysis of process analyser devices and infrastructure 3.7 toxic substances gaseous or liquid substances that, if released in a room, will cause a health hazard by contact with the skin or by inhalation from the surrounding atmosphere 3.8 safety back-up additional personnel, in constant contact with a person or persons in hazardous working condition, who could assist or call for additional help
IEC 61285 pdf download
