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 14 000 ×
10–6, 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 × 10–6.
Clause 7 addresses those measures for protecting personnel from
materials in the atmosphere of AHs that are hazardous to
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