IEC 61285:2015 outlines the physical requirements necessary for the safe operation of process analyser measurement systems installed within an analyser house (AH), with the aim of ensuring protection against fire, explosion, and health risks. It is applicable to analyser houses that may have internal or external explosive atmospheres and covers hazards posed by toxic substances or asphyxiating gases. (Consult national guidelines for toxic hazards.)
The standard does not cover facilities where the risk is posed by solids such as dust, powder, or fibres. It does not attempt to address all functional safety concerns related to analyser houses.
Section 4 discusses the positioning of the AH and its connections within the process plant areas. Section 5 focuses on the design, construction, and arrangement of the AH, but does not cover components of the analyser measurement system located elsewhere, such as in sample conditioning rooms (SCR) or switchgear rooms.
Section 6 details measures to mitigate the risk of explosion for AHs, while still allowing for equipment maintenance with the power on and the housing open.
For the majority of fluids, the primary constraint is that the concentration of vapours, which are harmful to personnel, must be below the lower explosive limit (LEL) (refer to Clause 7). Taking n-Pentane as an example, the LEL is 1.4% or 1.4 × 10^(-6), and the immediately dangerous to life or health (IDLH) level, which is the maximum concentration from which a worker could safely escape within 30 minutes without any hindrance to escape or irreversible health effects, is only 0.5% or 5 × 10^(-6).
Section 7 addresses the protective measures for safeguarding personnel from health hazards posed by materials present in the atmosphere of AHs.
