The human factor in measurements
Dr. Selim Erhan, TLT Editor | TLT From the Editor February 2022
Standard methods of measurement are key to the scientific process, but even the tiniest variances in the way humans carry out procedures can change the results.
In my opinion, the world is steadily becoming a better place as far as finding information is concerned. People are traveling more and exchange information wherever they go. In fact, the exchange of knowledge started with the first migrations and became vibrant with the silk trade and the spice trade throughout the ages. Even today, it is growing richer every year. Cuisine has become much richer with the availability of different recipes. This brought accessibility to fruits and vegetables that locals did not use or know before. But not only cuisine—almost every aspect of life has benefited. Architecture, gardening, clothing styles and technology all have benefited from the richness in diversity. The human ingenuity does not have borders, and sharing and accessibility have made life much more interesting for most of us.
One area that has brought great ease into our lives in the technical fields is the standardization of methods for measurements. It has an important role in normalizing communications in technology. We can all talk the same language and can be on the same page! We can move on to the next step in our process based on data we receive sometimes from the other end of the world! But then comes the human factor.
Recently, we heard from a lab that was preparing our certificate of analysis that the product was outside the agreed upon viscosity range. They could not allow the shipment. That was odd since we were dealing with vegetable oils, and the soybean plants that manufacture the oil are very consistent in their production as all natural processes. So, I decided to see what the issue could be. I visited the laboratory that was measuring the viscosity with a Brookfield viscometer. The spindles and rpms were all selected as agreed. The oil was heated on a hot plate to the required temperature using a calibrated thermometer. What followed next was the cause of the out-of-spec measurements.
The beaker, once at temperature, was carried across the laboratory to the instrument, the spindle was put in place, making sure there were no air bubbles underneath, and measurements were taken, but, alas, at now a lower temperature! The oil had cooled in the process. Not much, but for a measurement that is sensitive to +/-0.01 C, it was enough to push the data out of spec. I have heard other stories related to viscosity where the night shift had drilled a bigger hole in a Zahn cup that measures viscosity by a calibration chart involving the size of the hole and the flow time. In the middle of the night, that ink was flowing too slow for the operator. The quality control manager was not very happy when he had to make the trip to the plant at 2 a.m. Luckily these were discovered before they led to serious consequences. I have been in a large-scale plant trial where sugars in the simmondsin seeds were to be extracted with water, and the amount of water was specified. When we arrived at the plant, we saw the amount of water that had been used was 10 times the calculated amount. They said they had always filled the tanks to the level marked on the side and did not have any way of measuring the amount of water.
At some point, there seems to be a tendency to revert to a well-known practice. A practice so common that it seems harmless enough for a new procedure. In other words, what is written is not always read—and sometimes can’t be done. Of course, in cases of life and death like in the military or on ships, the orders of the commanding officer are always repeated back to make sure it was received as intended. So, human factor is not a new thing. It must always be factored in.
This brings an amusing example to mind. Of course, it is only amusing when we read from the comfort of our armchairs. Can you imagine how many ways the rhyme for coral snakes, one of the deadly serpents in North America, can be twisted by someone who is in proximity with a live snake? The rhyme goes like this: “Red touching black, safe for Jack. Red touching yellow, kill a fellow.” It is supposed to help people remember, but I have read versions that were created in the heat of events that were hilarious and, yet, very deadly if followed! How can we standardize human behavior? Or maybe we should simply enjoy the diversity, but keep in mind that it is a factor!
Dr. Selim Erhan is director of business development for Process Oils Inc. in Trout Valley, Ill. You can reach him at serhan@processoilsinc.com.