CALIBRATION FEATURE Managing the instrument lifecycle
Instruments are critical pieces of equipment, but they do eventually become obsolete. It is, however, possible to extend their useful life by using routine maintenance, servicing and calibration, as ABB explains
I
nstruments go through four phases in their lifetime. ‘Active’ is the sales and
manufacturing phase, and at the end of this volume manufacture ceases and the product moves into the ‘Classic’ phase. Complete lifecycle support is guaranteed throughout these two phases. The third is the ‘Limited’ phase, where
product support is gradually ramped down, and this then ends in the Obsolete phase where no product support is offered for the instrument. Most vendors keep to the same scheme, with roughly equivalent durations for each phase. On average, an instrument can have
a lifespan of 10-15 years as long as it continues to be supported, and it is not unknown for obsolete equipment to still be in use when it is 20 or more years old. However, when it does become obsolete, even though it may be working perfectly and doing the job it is supposed to do accurately and well, the lack of any technical support or spare parts will mean it is nearing the end of its practical working life. This can lead to more inaccuracies in reading, resulting in a possible degradation in product quality. Inaccuracies in flow measurement of such commodities as gas or water could reduce a utility’s profits, while large offsets in critical instruments could have serious consequences for safety or result in non- compliance with regulatory requirements. In addition, a consistently inaccurate
instrument could erode confidence in its ability to provide a reliable measurement, leading to staff ignoring its reading. This could prove particularly problematic in applications such as measuring the purity of water driving turbine blades, for example. Inaccurate readings could lead to a build-up of mineral deposits on the turbine blades, causing significant pitting and other damage. In these cases, the instruments are
monitoring, not controlling, and users need to be aware that if an electrical fault occurs they will need to be replaced.
PROLONGING INSTRUMENT LIFE The useful life of an instrument can be extended by ensuring routine maintenance, servicing and calibration are conducted according to the manufacturer’s recommendations. It is also important to have the right instrument, that has been
properly sized and specified for the application, and which is able to handle operating conditions such as ambient temperature and vibration. A user should also have contingencies
for when the instrument does breakdown, including having an arrangement in place to call out the manufacturer or its agents to repair a failed instrument. With response times varying between manufacturers, identifying both the effects that breakdowns can have and high risk instruments is essential in choosing the desired response time. For super-critical applications that must be back on line to comply with regulations or to avoid serious losses in revenue, a 24 hour response may be vital. In one example, an ABB customer was
losing £20-30,000 for every 3-4 hours the instrument was down. Another is one of the UK’s main airports, which employs instrumentation to measure the run-off of cleaning chemicals used on the runway. The airport needs a 90% up time for the instrument and every four hours off line counts as a full day, meaning 24 hour response is essential. Power stations also need this type of fast response as they must adhere to strict emission levels laid down by the Environment Agency. Having a fast repair response from the vendor must be balanced against the criticality of the application, the losses incurred on failure and the increased cost of the rapid reaction. In the past it was common for users to keep one unit in use and another on standby, although this is now less common. Similarly, fewer users now keep an extensive spares stock, preferring their instrumentation suppliers to hold bonded spares on their behalf. Instigating a lifecycle plan means
instrumentation users can plan upgrades and repairs effectively.
PHASES Understanding which phase your instruments are in and which course of action to take to maximise their life is the aim of a Life Cycle Assessment or LCA. Available from ABB, this begins with a life cycle audit to highlight the condition of the equipment, its revision status and necessary maintenance needs for its operating environment.
This helps formulate the best maintenance programme and identifies the appropriate migration points. The process begins with a site survey
of installed instrumentation and analyser equipment, followed by an evaluation of the life cycle status of ABB and third party equipment. The condition of the products is evaluated and their installation to ISO guidelines is confirmed. The final stage is a comprehensive inventory and life cycle report, including recommendations. This approach provides the knowledge
of the equipment condition and revision status to aid maintenance planning and costing. It also helps set out a life cycle management plan to prolong equipment life and avoid premature failure, while also assisting with the development of life cycle planning and budgeting. Following this is a life cycle management
service to provide effective maintenance, migration and obsolescence planning as part of an integrated programme. This implements recommendations from the life cycle audit and develops preventative maintenance schedules for installed devices based upon criticality. It also implements appropriate predictive maintenance technologies, as well putting in place any support functions needed. Furthermore, it enhances the condition
and reliability of instruments and extends operating life. It also makes the correct resources and parts available for upgrades, while providing lower cost of ownership and minimal disruption.
ABB T: 01480 488080 INSTRUMENTATION | DEC/JAN 2016 23
On average, an instrument can have a lifespan of 10-15 years as long as it continues to be supported
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