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David Trew

Consulting Ltd

Management of Equipment in an ISO/IEC 17025:2017 Accredited Laboratory

Part 1: Classifications of Laboratory Equipment

1 Introduction

The International Standard ISO/IEC 17025:2017 General Requirements for the Competence of Testing and Calibration Laboratories, published by the International Organisation for Standardisation and the International Electrotechnical Commission, is the principal international quality assurance scheme for testing and calibration laboratories. This International Standard and the associated policies and guidelines are general documents intended to apply to the entire spectrum of testing and calibration activities. Therefore, they leave significant room for customisation by the individual laboratory to meet its specific requirements.

Clauses 6.4.4 and 6.4.5 of this International Standard require the laboratory to verify that measuring equipment or instrumentation conforms to specified requirements before being placed or returned into service, and can achieve the measurement accuracy and/or uncertainty required to provide valid results throughout the lifetime of the instrument. For a small calibration laboratory that is accredited to carry out just one or two calibrations, such as the temperature calibration of freezers and refrigerators used to store food, the investment necessary to ensure conformance with these Clauses is not great, only consisting of servicing and calibrating the primary thermometers together with a periodic check with a water triple point cell2.

The situation is quite different for a laboratory performing a larger number of tests using complex measuring instrumentation. In these situations, the concept of risk associated with a failure of a measuring instrument is frequently applied. Indeed Clause 8.5 of the ISO/IEC 17025 International Standards mandates laboratories assess the risks associated with their operations

The risks associated with an equipment failure need to be managed and controlled. First, this is done by identifying the risks of a failure and the consequences for the customer and the laboratory if the failure were not detected and corrected. Once the risks and their associated consequences have been identified, controls need to be identified and implemented. These controls ensure that the instrument constantly performs to established specifications throughout its entire operating life, including routine preventive maintenance and calibration. For a laboratory with many complicated measuring instruments, this can become expensive in terms of the costs to perform the routine maintenance and calibrations and the downtime required to perform such activities when the instrument cannot be used to generate revenue. It is obvious the more preventative maintenance and calibrations carried out, the greater the cost.

The challenge is to optimise the level of assurance, which lies somewhere between doing nothing and total assurance that the instrument is performing to established specifications and capable of providing valid results at an acceptable cost; this is illustrated graphically in Figure 1.

Level of Assurance

Figure 1: Optimisation of Quality Assurance, Increase in Value and Costs

When done at the start of the process, the risk level associated with a measuring instrument failure, represented by the red line with no investment, is high. The level of risk is reduced as investment, represented by the blue line, is increased. However, after a certain point, represented by A where the red and blue lines cross, in Figure 1, progressively higher investment is required to achieve a minimal reduction in the level of risk.


The red line in Figure 1 can also be considered the potential cost of a failure of the measuring instrument. The thick green line in Figure 1 represents the combination of the cost associated with a failure of the instrument and the level of investment; This shows there is an optimum range where the combined cost of risk and investment is at a minimum. The challenge is the find this optimum range of investment and level of risk.

For a laboratory with even a moderate amount of equipment management, determining the appropriate amount of maintenance and calibration for each instrument, together with managing, scheduling, and recording all calibration and maintenance activities, can become a significant logistic activity. Which, unless carefully managed, can lead to incorrect maintenance or calibration decisions being made. To help efficiently manage the logistic workload, classifying equipment into different categories is discussed in this paper. This classification, which can be based on different criteria, will enable different equipment with similar uses or complexity to be managed in a similar manner.


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