To help convince still-reluctant colleagues and managers of the value of field calibration, Schmeck says advocates should sell its value and educate others about its benefits.
"In pharmaceutical manufacturing, we stress that calibration can mean better batches. In power generation, calibration can help producers waste a lot less electricity," explains Schmeck. "We use field calibrators at Merck because they make monitoring much easier and because we can have far fewer items breaking sterility. For example, it's much easier today to take one multi-function calibrator into a sterile setting. In the past, we had to break sterility to take an instrument out of production, bring it to a shop, bench calibrate it and break sterility again to reinstall it."
When deciding where to use field calibrators, Jim Shields, Fluke's field calibration product manager, says that potential users need to identify critical tags in their applications; define the appropriate intervals for performing calibration; make sure they're not compromising safety; evaluate process quality and maintenance costs versus returns to the process; examine cost optimization; weigh environmental and non-compliance costs; and identify other tags and longer intervals between calibrations. "You must also evaluate the software and associated calibrators available to do the job. This is not always a one-size-fits-all proposition. All the software packages for managing calibration have different strengths and weaknesses," adds Shields.
Configuration is Not Calibration
Besides talking up calibration's advantages, some users and suppliers find they also must educate potential users about the fact that initial configuration doesn't mean calibration. "The biggest problem we face is when someone sets up a transmitter or loop in the field and thinks that using a handheld communicator to set it up means it has been calibrated. It hasn't been calibrated, but this problem happens a lot," says Tom Fatur, Martel's president. "For example, they may configure a transmitter to transmit at 0 psi to 500 psi, and then think they can walk away. However, they must also verify that it's working properly by hooking up a field calibrator to introduce a simulated physical parameter. "
Likewise, some suppliers may imply that their transmitters or other equipment are more stable than they actually are, and so need less calibration or less maintenance than they actually do. "A salesperson may come in with a new pressure transmitter and guarantee that the electronics won't drift for 10 years," explains Schmeck. "Now, he hasn't actually lied, but the user may not have asked the right questions, because the diaphragms on that transmitter will definitely change over time. So while the electronics may not change, the performance and readings will drift. You can't not calibrate a transmitter for 10 years, even though the sales pitch may make it sound like you can. Most transmitters need to be re-calibrated once per year."
New Realms, New Requirements
Though some process control technologies are shrinking as automation and PC-based control take over, it's likely that field calibration is going to become more important because it gives automated systems an essential connection to real-world operations and is the foundation of precise data on which all their calculations. are based. Plus, calibration helps deliver the documented accuracy and traceability that more applications will require in the future.
"I used to work at a chemical plant, and if the resins we made didn't make the grade, we could just reuse the materials," explain Schmeck. "In pharmaceuticals, if a medicine doesn't meet all the criteria required during each step, we have to throw it all out. So even though calibration is more important in pharmaceuticals now, I think it's going to become more important in other industries. For example, in the U.S., we're trying to find all the natural gas we can, and this is opening a whole new realm of instrumentation and calibration. Also, we're going to have a lot more wind and solar power applications, and they will need instruments, monitors and calibration too." Oh, and get an eye exam.