By Marc Paquette and Scott Dolan, VT Agency of Agriculture, Food & Markets
State and local jurisdictions throughout the country are celebrating Weights and Measures Week which takes place on the first seven days of March each year. The date for Weights and Measures Week commemorates the signing of the first United States weights and measures law by President John Adams on March 2, 1799. This year the Vermont Weights & Measures program, located in the VT Agency of Agriculture Food & Markets, would like to highlight the Metrology component of the program.
Metrology not Meteorology
Knowing the weather ahead of time and taking for granted that everything you buy, or sell is based on standard quantities are both invaluable serves provided by a mix of public and private entities. Metrology is the science of weights and measures, which is completely distinct from meteorology, the science of weather forecasting and atmospheric analysis.
Forty-two states operate metrology laboratories that diligently provide calibration services to countless public and private organizations. Nationally, these laboratories provide calibrations for mass, volume, length, frequency, thermometry, and density standard. Notably, the National Institute of Standards and Technology (NIST) even maintains a one-million-pound weight for calibrating extremely large force sensors. These state-run metrology laboratories, supported by the NIST Office of Weights and Measures, have formed the foundation for consistency and confidence in all commerce and weights and measures enforcement programs in the United States and beyond.
Everyone employed as a metrologist in one of these state-run NIST-recognized metrology laboratories must have completed over 160 hours of on-site training at the NIST Campus in Gaithersburg, Maryland. Additionally, they are required to attend annual training provided by NIST around the country. During the first week of June in 2025, NIST will be holding its National Measurement Assurance Program Training in Portland, Oregon. As part of NIST’s Measurement Assurance Program, all labs must submit reports annually and complete proficiency tests in a range of measurement categories to prove they continue to meet NIST’s rigorous standards.
The Vermont Metrology Laboratory, located at Vermont Agricultural and Environmental Laboratory (VAEL) in Randolph Center, provides calibration services to 137 different organizations across the Northeast United States. These services encompass a range of measurements, including calibrations of mass standards between 1 mg (shown in figure 2) and 7000 lb (shown in figure 3), volume standards from 5 gallons to 200 gallons, and hydrometers used by the maple industry in Vermont and beyond. These artifacts must undergo annual calibration to maintain the required precision and accuracy for their continued use.
To give you an idea of the required precision and accuracy when carrying out this work, three examples are provided.
- When calibrating a 7000 lb weight cart (a device used to test large truck and hopper scales) our instrument takes reading in increments of 0.011 lb (or 5 g).
- When calibrating a 1 lb weight, we take measures down to 0.0000022 lb (or 1 mg) to ensure that 1 lb weight is within the 0.000154 lb (or 70 mg) tolerance for commercial field work.
- When calibrating a 1 mg weight, readings are taken to the 0.1 μg (we are not providing the pound equivalent here because there are too many zeros).
Most of the companies we service provide calibration services for gas pumps, oil and propane delivery trucks, and scales of all sizes that people use every day. We also offer calibration services to private manufacturers. Each year, the lab certifies that over 2000 weights and over 100 volume standards meet the requirements for use in the weights and measures field.
In Vermont, all maple syrup and sap hydrometers sold must undergo testing in the metrology lab for accuracy before they can legally be sold in the State of Vermont. We receive on average 8,000 maple hydrometer each year from US, European and Chinese manufacturers.
Metrology is a largely invisible part of everyone’s life even if most days our labs are behind closed doors.
For more information, please contact Scott Dolan by email at scott.dolan@vermont.gov or by phone at 802-522-5415
