IEC TR 62010 pdf download Analyser systems – Guidance for maintenance management
4.2Safety protection
IEC 61508 defines the requirements for E/E/PES devices in all safety related systems. Thistechnical report does not seek to add to or modify the requirements of that standard inrelation to a method for determining analyser priority on safety issues and takes the principleand general format of the risk-graph approach for IEC 61508-5.However,as this technicalreport is aimed at analyser maintenance priorities, it must be re-emphasized that the rankingsystem adopted is in line with accepted analyser maintenance practice,i.e. the highestpriority is 1 and the lowest priority is 3
The following should be noted when considering the use of analytical instrumentation asmeasuring elements for safety-related systems.
The mean time between failure of analytical instrumentation is lower than standardinstrumentation used in safety-related systems (pressure,temperature and flow measure-ments). This is especially true of complex analysers such as spectrometers and gaschromatographs.
Should analytical instrumentation be utilized in safety-related systems,duplex and triplexsensors,and frequent proof-checking would routinely be required to achieve the necessaryon-line times. These should be determined in accordance with the procedures and rules laiddown in IEC 61508 – the above risk-graph usage in this technical report is intended as aguide only to setting maintenance priority and is not intended as an alternative route todefining safety-integrity levels (SIL).
4.3Environmental protection
Measurement of variables which impact directly on the environment are an increasinglyimportant function of on-line analytical instrumentation. Data produced by environmentalanalysers may require submission to governmental bodies concerned with legal andprocedural aspects of environmental monitoring.
There is significant diversity in the nature of the techniques. Traditional applications andmethods are continuous air monitoring (CAM) and vent-emission monitoring by gaschromatography or electrochemical sensors, organics in aqueous effluent by total carbon (Tc)and total oxygen demand (TOD), and acidity/basicity of aqueous effluent by electrochemicalpH sensor. These are supplemented by more modern techniques such as air-qualitymonitoring by open-path spectrometry and elemental analysis by X-ray fluorescence.
Failure of the analyser to perform its specified function may lead to consequences R1 , R2, or R3 depicted in Table 1 . It should be noted that environmental analysers are often used to record data, but examples whereby analyser failure leads direct to consequential damage are far fewer.
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