From lottery ping pong balls to airliner fuel tanks, he makes sure they measure up
January 22, 1997. . . Ever wonder who, if anyone, makes sure the ping pong balls used by the Oregon Lottery each week all weigh the same to ensure numbers are drawn completely at random? Or who is it that helps somebody like Boeing measure exactly the amount of fuel that can be held in an aircraft tank?
Meet Jim Ross, state metrologist with the Oregon Department of Agriculture's Measurement Standards Division. Ross calibrates physical standards of mass, volume, and length for public agencies like the Oregon Lottery and private industry. From calibrating sensitive equipment used by the electronics industry that measures one-millionth of a pound to calibrations on a 100,000 pound railroad track scale test car, Ross is the state's official keeper of standards of measurement.
"Metrology is essentially concerned with the standards of measurement that are used for calibration of other equipment," says Ross. "Those standards are used to calibrate any weighing or measuring device used in the United States."
Ross is rather modest about his work, but without some sort of guarantee on measuring standards, somebody else's idea of what a pound is may be in error.
"The marketplace is governed by accurate standards," says Ross. "The consumer needs to know when they make a purchase that they are getting what they pay for. The only way you can ensure that is to have accurate standards to compare against. That's the reason standards were developed in the first place. One person said his pound was a pound and the other guy said no, his pound was a pound. They couldn't agree on whose was a real pound. Well, we have the real pound and when they want to know what that is, they come to us."
Ross does not have a desk job. Sometimes he travels to other parts of the state, but most of the time he can be found at the metrology laboratory in Salem-- often doing very intricate work in comparing somebody else's mass standards with the official set, which is carefully kept at the lab.
"In the lab itself, anything that is a very high precision device has to come in because of the environmental control that have to be used," says Ross.
The act of calibration is very sensitive to temperature, humidity, and barometric pressure. That's why measuring devices such as high accuracy jeweler scales must come inside. What is called an ultra-micro balance needs to be protected from any air drafts and must be placed inside the lab's controlled environment for 24 hours so it can stabilize with the room's conditions.
"Most of the calibrations we do in the ultra-high precision range are for silicon chip makers and for medical laboratories," says Ross.
The law requires that anything used to measure or weigh commercially must be calibrated. However, there are plenty of non-commercial applications that the Measurement Standards Division will handle by request, for a fee. Some of those requests can be quite interesting-- many downright critical.
"We calibrate airline fuel tanks because pilots want to know how much fuel they have so they know what their range will be," says Ross. "We bring the fuel tanks in and calibrate them to whatever amount of fuel we can get out in a normal flight."
This is done by actually building a template of an aircraft wing that the fuel tanks will sit in. Reproducing or simulating the actual setup is important.
Other less glamorous, yet still important calibrations are part of the job, such as making sure black cod measuring devices used by the National Marine Fisheries Service are accurate. If a fish caught by an angler fits in the box and doesn't touch both ends, it's too small and the fisherman can be fined for not meeting the length requirement set by officials.
Metrology labs often get involved in dispute resolution, as was the case in another state where an apparent NCAA shotput record in a track and field event was later disputed. The steel tape measure used to record the distance of the throw was correctly calibrated. But upon further challenge, the shotput itself was weighed and found to be inaccurate. The intercollegiate record was thrown out.
Ross has been known to receive shotputs and discuses from local
track and field events, including the NCAA Championships hosted in
Eugene a couple of years ago.
And then there are the ping pong balls.
"The Oregon Lottery wanted to make sure its security couldn't be challenged and that the ping pong balls used in drawings would always come up in a random manner," says Ross. "My predecessor, Jim Clifford, came up with a system to make the selection of lottery balls as random as possible."
There are five sets of balls used by the lottery. By weighing each set of 44 lottery balls, Ross essentially sorts them by weight. Most balls weigh approximately 2.5 grams (it would take about 180 balls to make a pound) and weigh within 100 milligrams of each other. But by placing all the lightest balls numbered 1-44 in one set, the next heaviest balls 1-44 in the next set, and so on, each set has balls that are pretty much the same weight.
"By doing it that way, there isn't a heavier or lighter ball in the set that is going to come up any more often than another one," says Ross.
In each case, it is the Oregon Department of Agriculture, specifically the Measurement Standards Division, and even more specifically, Jim Ross that guarantees the integrity of weights and measures through the process of calibration.
No way-- or perhaps more accurately-- no "weigh" should it be taken for granted.
For more information, contact Bruce Pokarney at (503) 986-4559.