This document is written with the intention of providing an understanding of analyser maintenance to individuals from a non-engineering background. It is also designed as a reference source to individuals more 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, resource 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 one of the following reasons :

Safety and Environmental

One category of analysers are 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 upon demand.

Asset Protection and Profit Maximisation

On-line analysers falling into this category are normally those impacting directly on process control. They may impact directly on protection of assets (e.g. corrosion, catalyst contamination) or product quality, or may 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 should be installed on the process may be sought by quantifying the payback time of the analyser, the pass/fail target typically being 18 months, although it should be noted that 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.

The document focuses on the costíbenefits associated with traditional analyser maintenance organisations. In a modern set up the complexity of analysers demands on occasion data from chernotricians and scientists who may be owned by other parts of the organisation, and as such care must be exercised to include their costs.