Comparing Deadweight Testers with Digital Pressure Calibrators


When choosing which instrument to use when calibrating pressure, two of the more popular choices are deadweight testers or digital pressure gauges/calibrators with a pressure comparator. Each has their advantages and disadvantages, which are discussed in detail below.


The deadweight tester has long been the standard for pressure calibration. However, advancements in technology have led to the development of digital pressure standards worthy of consideration in lieu of a deadweight tester. Understanding how to contrast the two technologies is key to selecting the appropriate solution.

Deadweight testers are systems that physically generate a known pressure. They may also be used as gauges to accurately measure system pressure. These devices do not require a display, as the combination of the masses is used to determine the output pressure. They operate under the simple formula that pressure is equal to force applied over a known area. The deadweight tester output is typically very accurate, even at its lower ranges. Industrial deadweights are available with accuracies to ±0.015% of reading.

By contrast, digital pressure standards must be combined with a pressure source to generate a known pressure. Without the capability of producing pressure, the digital standards are technically gauges. However, in the market, they may be called calibrators to distinguish them from the lower classes of digital indicators. These digital devices are typically available in accuracies as a function of their full scale, such as ±0.050% of full scale (FS). However, advancements in technology have led to some instruments specified as a function of the reading, similar to deadweight testers. Accuracies are available as low as ±0.025% of reading.

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