Generally, all commercially used weighing devices are tested for accuracy. In addition to being accurate, devices must adhere to specific design and installation requirements (NTEP), and be used correctly. The most familiar types of devices are the scales used at store check stands. As we enter the 21st Century, technology is rapidly changing.
Many scales now are interfaced with computers. The Standards Specialist now must inspect "systems" which can consist of multiple components such as:
Instruments used to determine volume, distance, dimensions, and time are all measuring devices. The device that people are most familiar with is the gas pump. Inside the cabinet is a meter that determines the quantity of fuel dispensed. Standards Specialists test each meter by dispensing 5 gallons at the fast (or open) speed then 5 gallons at the slow (restricted) speed into calibrated measure, compare the monetary computations, check that the tamper-proof seal on the meter adjustment is intact, and other details required in the Examination Procedure Outline distributed by Measurement Standards. Other measuring devices include:
Wire and rope meters
Wholesale water meters
Timers in car washes, Laundromats, parking garages, milk tanks and propane meters
Each meter type requires its own special test equipment; a taxi test wheel; calibrated tape measures; test vessels and a stopwatch.
Calibrations can be either dry or liquid. We test our field standards to maintain a chain of accuracy. Our standards are verified by Indiana Weights and Measurements periodically for accuracy.