Linda on field calibration: “We never know what to expect”

Published 2022-12-19

Imagine creatures carefully covered in double layers from head to toe moving methodically in controlled environments. No, it is not a science fiction movie. These are commonly used scenes from field calibration. That is, calibration of measuring equipment on site at customers’ premises.
– We never really know what to expect and what will happen, says calibration engineer Linda Wiman with a laugh.

Field calibration is done at companies that either cannot do without their sensors and data loggers or have fixed measuring equipment that is difficult and time-consuming to remove. Linda Wiman and her colleagues in the calibration team at Nordtec go to these customers around Sweden. They carry high-precision lab instruments that are used for comparative measurements of customers’ measuring equipment.

These comparison instruments are sensitive to transportation. To ensure their reliability, Linda makes a comparison measurement in an ice bath before going on a field mission.

– Then we repeat the same measurement when we are back in the office again, to see if the measurement accuracy has changed. For moisture sensors, we check them in a similar way to measure accuracy before and after the customer visit,” says Linda.

Depending on the nature and scope of the mission, different amounts of equipment and manpower are needed. If it’s too much and too heavy to do by herself, Linda needs the support of one or more colleagues.

– If it is an accredited field calibration of both humidity and temperature, it will be quite a lot of equipment. For example, we have a humidity chamber with its own large special bag on wheels. And for temperature measurements we have a block oven which is also transported in a large bag.

What does the customer need to do before you arrive?
– We send an information sheet to the customer that says: “Consider the following…”. For example, I may need a working electrical outlet and a rolling table to put my things on. It is also important that staff know where the sensors are located and that nothing prevents the reading.

– There are unnecessary costs for the customer if I have to wait for two hours before I can access a sensor. It is also important to inform in advance that we need to be able to log into the measurement system software. It is rare that all staff at the customer have their own login.

Do field missions require special clothing?
– For example, if we are in a research lab where there may be risks to us, we are provided with protective clothing. In a refrigerated warehouse of a food wholesaler, we need big down jackets, hats and mittens because we are going to work in minus 20 degrees. And when it comes to really sensitive environments, we sometimes need full coveralls, which should not even be touched on the outside (!) when you put them on. Add double gloves and a beekeeper’s hat, and you can see what it can look like,” says Linda, laughing.

– It’s not uncommon for the customer’s lab coats to be too big, so we bring our own disposable coats to make it easier to work with.

No two jobs are the same, which is what makes working in field calibration so stimulating.

– On one occasion, a data logger was located in a sheltered area, but the readings were taken elsewhere. Several readings were needed, but it was only possible to read one value at a time by pressing a button on the logger. So I had to put on a hairnet, booties and protective clothing to go in and press the button. Then go out, take everything off, read the value, change back into the protective clothing, go in and press the button. Over and over again. That particular incident caused great amusement in the company,” says Linda, smiling at the memory. ■

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