Optimizing instrument performance through enhanced condition monitoring

Condition monitoring insights

• Today’s process instruments have largely moved away from the analog technologies of the past to become digital.

• Condition monitoring of process instruments allows end-users to keep a constant check on the health of measurement devices.

• This allows end-users to keep their processes operational for longer periods of time while meeting regulatory requirements in a cost-effective way.

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From water treatment plants through to petrochemical facilities, most industrial processes rely heavily on a wide range of process instrumentation. Devices such as temperature and pressure transmitters, flowmeters, and gas and liquid analyzers are all used to ensure accurate measurement and control.

Although plant managers are largely concerned with the correct operation of the process, the instruments that provide the data also need attention. They need to operate reliably and accurately to ensure the process is running correctly, so their own health and performance also need to be a priority.

Today’s process instruments have largely moved away from the analogue technologies of the past and most are digital. As well as producing data about process parameters, these instruments also produce a wealth of information about their own performance and accuracy. Many modern devices can check their own circuits for errors and evaluate their own performance which can help technicians conduct calibration and maintenance.

Condition monitoring of devices brings several benefits, including the ability to keep a constant check on the health of measurement devices. In some cases, this information can be shared with the device vendor, whose experts can offer service recommendations based on the device’s health status and remote assistance. Some providers take data from their devices and offer a full online condition monitoring system to help users make better decisions regarding the status and future of their devices.

Another major benefit is reduced maintenance. Many instruments can contribute to maintenance through self-cleaning; however, an accurate assessment of the condition of the device allows users to move to a predictive maintenance regime. This avoids the need to conduct time-consuming scheduled maintenance and can be an important factor if the device is in a remote area or is difficult to access.

Self-diagnosis also helps a device achieve maximum uptime. This can be especially important for critical operations such as gas emissions monitoring systems. As they monitor potentially harmful gasses, regulations governing the availability of these systems are becoming increasingly strict. In countries with the most restrictive regulations, operations may only have a maximum of 10 invalid minutes per half-hour, 5-6 invalid half-hour averages per day, or 10 invalid days per year.

Condition monitoring can also encompass remote monitoring. This is where managers are kept constantly aware of their instruments’ condition via alerts sent directly to their smartphone or tablet.

Gaining benefits

An essential first condition to take advantage of these abilities is to achieve effective communications with the device. Although most measurement devices are digital, many applications still make use of the 4-20mA current loop.

Another essential is the ability to interrogate the device. One of the major methods is inbuilt condition monitoring and diagnostics based on the NAMUR NE 107 standard. Essentially, NAMUR NE 107 categorizes internal diagnostics into four standard status signals – failure, function check, out of specification and maintenance required. This makes it easier for technicians and other process personnel who need to deal with alarms.

The status signals can also contain greater detail. For example, a failure signal could include information regarding a problem with the device, or if the process itself is the source of the fault.

Flexibility is also a major feature of NAMUR NE 107 diagnostics – users can turn off any diagnostics that are not needed or can configure how the diagnostics are reported.

Accurate verification

Field verification is a vital step in maintaining a device’s accuracy. Manual verification has been widely used in the past. Based on the use of multimeters and similar devices, this requires trained technicians and results in longer downtimes. A faster option is software verification. However, this can require the use of several different software packages that may not always work with all communication protocols.

The best modern verification software packages are more automated, requiring no specially trained technicians. They can support many device types, performing a deep analysis of the device’s condition, producing a report on the calibration variables, and determining if the device has passed or failed.

An example of the benefits possible from automated versus manual verification is an organization that used the technique to achieve an annual reduction in costs of over $1 million. The organization originally spent $150,000 a year on verifying 75 measurement devices for regulatory purposes, while annual maintenance and repair came to $100,000. It also lost 5% of its production due to poor quality. By moving to automated verification, the company reduced total maintenance by a minimum of $162,000 and increased throughput by $130,000.

The most powerful and cost-effective maintenance method is predictive maintenance and condition monitoring is its essential basis.

Predictive maintenance uses performance data to predict which device and which component on the device is likely to fail and when. Maintenance staff can investigate the device’s condition more effectively, conducting tasks to fit with production schedules and carrying out repairs before the instrument fails. With a better insight into the actual condition of the instrument, it can be serviced in the right way at the right time, increasing its lifespan.
One of the major benefits of a predictive maintenance program is the reduction it can achieve in unplanned downtime – if an instrument is only taken out of service when necessary, it can continue to carry out its monitoring role for the maximum length of time.

A further benefit is the ability to schedule tasks more effectively, making more efficient use of the workforce.

Moving away from preventive maintenance and towards predictive maintenance can help eliminate routine tasks that add no value or do not improve the operation of the device. As well as reducing overall maintenance costs, this will also eliminate the risk of making inaccurate adjustments.

Summary

Modern measuring and monitoring instruments offer great advantages by aiding in their own condition monitoring to inform predictive maintenance. In this way, they are kept operational for longer; ensuring instrument users across any industry can keep their processes working for the longest possible time in a cost-effective way, while also meeting the relevant regulatory requirements.

– This originally appeared on Control Engineering Europe.

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