Benefit from using documenting calibrators
14 July 2009
For process manufacturers, regular calibration of instruments across a manufacturing plant is common practice. In plant areas where instrument accuracy is critical to product quality or safety, calibration every six months – or even more frequently – is not unusual.
Benefit from using documenting calibrators
However, the key final step in any calibration process – documentation – is often neglected or overlooked because of a lack of resources, time constraints or the pressure of everyday activities.
Indeed, many manufacturers are now outsourcing all or some of their maintenance activities and so the contractor too is now under the same pressure to calibrate plant instruments quickly but accurately and to ensure that the results are then documented for quality assurance purposes and to provide full traceability.
The purpose of calibration itself is to determine how accurate an instrument or sensor is. Although most instruments are very accurate these days, regulatory bodies often need to know just how inaccurate a particular instrument is and whether it drifts in and out of specified tolerance over time.
A documenting calibrator is a handheld electronic communication device that is capable of calibrating many different process signals such as pressure, temperature and electrical signals, including frequency and pulses, and then automatically documenting the calibration results by transferring them to a fully integrated calibration management system. Some calibrators can read HART, Foundation Fieldbus or Profibus output of the transmitters and can even be used for configuring ‘smart’ sensors.
Heikki Laurila, product manager at Beamex in Finland commented: “I would define a documenting calibrator as a device that has the dual functionality of being able to save and store calibration results in its memory, but which also integrates and automatically transfers this information to some sort of calibration management software.” A non-documenting calibrator is a device that does not store data, or stores calibration data from instruments but is not integrated to a calibration management system. Calibration results have to be keyed manually into a separate database, spreadsheet or paper filing system.
By using a documenting calibrator, the calibration results are stored automatically in the calibrator’s memory during the calibration process. The engineer does not have to write any results down on paper and so the whole process is much faster and costs are therefore reduced. Quality and accuracy of calibration results will also improve, as there will be fewer mistakes due to human error. The calibration results are transferred automatically from the calibrator’s memory to the computer/database. This means the engineer does not spend time transferring the results from his notepad to final storage on a computer, again, saving time and money.
With instrument calibration, the calibration procedure itself is critical. Performing the calibration procedure in the same way each time is important for consistency of results. With a documenting calibrator, the calibration procedure can be automatically transferred from the computer to the handheld calibrator before going out into the field. As Laurila stated: “Engineers who are out in the field performing instrument calibrations, get instant pass or fail messages with a documenting calibrator. The tolerances and limits for a sensor, as well as detailed instructions on how to calibrate the transmitter, are input once in the calibration management software and then downloaded to the calibrator. This means calibrations are carried out in the same way every time as the engineer is being told by the calibrator which test point he needs to measure next. Also, having an easy-to-use documenting calibrator is definitely the way forward, especially if calibration is one of many tasks that the user has to carry out in his or her daily maintenance routine.”
With a multi-functioning documenting calibrator, such as the Beamex MC5, the user doesn’t need to carry as much equipment while out in the field. The MC5 can be used also to calibrate, configure and trim Foundation Fieldbus H1 or Profibus PA transmitters.
Laurila continued: “With a documenting calibrator such as the MC5, the user can download calibration instructions for hundreds of different instruments into the device’s memory before going out into the field. The corresponding calibration results for these instruments can be saved in the device without the user having to return to his PC in the office to download/upload data. This means the user can work for several days in the field.”
Having a fully integrated calibration management system – using documenting calibrators and calibration management software – is important. Beamex CMX Calibration Software ensures that calibration procedures are carried out at the correct time and that calibration tasks do not get forgotten, overlooked or become overdue.
Northern Energy Services (NES) Limited, Doncaster based in UK is using Beamex® CMX Calibration Software and the Beamex MC5 Multifunction Calibrator to carry out instrument calibrations for its customers.
NES is a service provider for the power generation and petrochemicals industries. NES carries out a range of services for its clients, including routine maintenance, calibrations, installations, electrical services, fault diagnosis and repair, ATEX inspections and re-certifications.
David Tuczemskyi, Control & Instrumentation Engineer at NES has worked in his role for more than 10 years. He commented: “Most of our work is for gas-fired power stations in the UK and Ireland, which involves a significant amount of instrument calibrations. Typically, once a year for a major inspection, the plant will shut down for a month and we are called in to carry out all instrument calibrations across the site.”
In Tuczemskyi’s experience, the industry is often guilty of relying on manual paper-based systems for documenting instrument calibrations. As he explained: “Calibration is done manually, which takes longer and is prone to manual error. Often, the field engineer calibrates the instrument, handwrites the results onto a paper form of some kind, and then has to re-enter this information into a database on his or her return to the office. Unintentional errors often creep in here and the whole process is time consuming.” So, in the last few years, NES has issued its team of engineers with the MC5 documenting calibrator and the company has also bought the CMX calibration software. “We are actively pushing our customers, the power generation plants, to use Beamex’s hardware and software,” Tuczemskyi explained. Why? Because, said Tuczemskyi, you get higher accuracy, the calibration process is much faster and the customer gets full traceability. “What surprised me most when I started using the MC5 was that the calibration tasks were being done much faster but also more accurately. In our industry, a faster job usually means the engineer has cut corners. When you’ve got to calibrate 1,000 instruments across a site, typically with five-point checks on each instrument, speed and accuracy are critical.”
After completing instrument calibrations, NES typically provides its clients with a full quality assurance report of all instruments that have been calibrated at the site, along with a calibration certificate if required. “This not only ensures full traceability but looks professional and reflects well on us as a service provider,” stated Tuczemskyi.
Over the years, the biggest change that Tuczemskyi has seen in the UK power industry is in regulations and the auditing process. “You simply cannot get away with it now. Everything you do has to be traceable. The problem here is that the end customer has little or no time to spend with the contractor, so the contractor has to be fully competent in everything it does. The customer wants to outsource as much of the maintenance and calibration work as possible these days. MC5 enables us to perform all the required instrument calibrations on a site, but then automatically downloads this information to the CMX software. We perform all the necessary back-ups for the customer and the whole process is fully integrated and efficient.”
Instruments that require calibration are normally given a priority rating by the customer. Safety-critical instruments are often the highest and will be checked every three to six months with lower priority instruments only being checked once a year or less. “CMX removes all these issues and enables users to prioritise their instruments and then to receive automatic alerts when safety-critical sensors require calibrating. When it comes to plant safety, you cannot always rely on manual paper systems and poor databases.”
Tuczemskyi also likes the fact that the combination of using the MC5 and CMX means that instructions on how to calibrate an instrument and the order in which to calibrate can all be downloaded to the handset while the engineer is out in the field. “We did some calibration work for a customer on three gas turbines, two of which were running, the other on standby. Certain instruments we had to calibrate were on a common block trip and we knew from our own experience that we had to calibrate these in a specific order and method, otherwise we could inadvertently cause the one of the turbines to fail. A two-hour shut down on a gas turbine, for example, would have cost this customer around £100,000 in lost downtime. By using the MC5 and CMX software in situations like these, the contractor doesn’t have to rely on experience like we did, but can download specific instructions to the calibrator before calibrating the instruments, which ensures costly mistakes out in the field are never made.”
According to Tuczemskyi, it took NES engineers only two weeks to get to grips with the CMX software. “Technical support at Beamex is absolutely superb. Three years ago, we were under immense pressure to get a job completed, when we had a software glitch that prevented us from uploading or downloading calibration results. We contacted Beamex and the guys repaired our fault within two days.”
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