1 Scope
1.1 Purpose
This document is written with the intention of providing an understanding of analyser
maintenance principles and approaches. It is designed as a reference source for individuals
closely involved with maintenance of analytical instrumentation, and provides guidance
on performance target setting, strategies to improve reliability, methods to measure effective performance, and the organisations, resources and systems that need to be in place to allow this to occur.
Effective management of on-line analysers is only possible when key criteria have
been identified and tools for measuring these criteria established.
On-line analysers are used in industry for the following reasons:
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• Safety and environmental. One category of on-line analyser is those used to control and monitor safety and environmental systems. The key measured parameter for this category of analyser is on-line time. This is essentially simpler to measure than an analyser’s contribution to profits but as with process analysers applied for profit maximisation, the contribution will be dependent upon ability to perform its functional requirements on demand.
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• Asset protection and profit maximisation. On-line analysers falling into this category are normally those impacting directly on process control. They can impact directly on protection of assets (e.g. corrosion, catalyst contamination) or product quality, or can be used to optimise the operation of the process (e.g. energy efficiency). For this category of analysers, the key measured parameter is either the cost of damage to plant or the direct effect on overall profit of the process unit. Justification as to whether an analyser is installed on the process can be sought by quantifying the payback time of the analyser, the pass/fail target typically being 18 months. The contribution of the analyser to reduction in extent of damage to, or the profit of, the process unit, is difficult to measure. However, this contribution will be dependent upon the analyser’s ability to perform its functional requirements upon demand.
This document focuses on the cost/benefits associated with traditional analyser maintenance
organisations. Due to the complexity of modern analysers, support can be required
from laboratory or product quality specialists, for example for chemometric models,
who can work for other parts of the organisation. Inclusion of their costs in the
overall maintenance cost is therefore important.