Would a standard by any other name still calibrate as accurately?
In pressure calibration, there are many terms used interchangeably. One of these is primary reference pressure standard. What is it? It's the primary instrument you are using as a reference to measure pressure in a standard way. They usually refer to instruments such as deadweight testers, pressure balances and piston gauges, which are traceable to SI units. Using any of these devices is essential to a fully equipped pressure calibration lab.
These instruments provide a pressure reference to compare the reading of a device under test during a calibration. For example, a pressure transducer may be used in the field to accurately measure a process pressure or to test and calibrate instruments on a production line. To ensure consistent and accurate measurement, these instruments require a more accurate calibration involving a primary reference pressure standard. It is important for a reference standard to be as accurate as possible in order to ensure these field pressure devices meet their accuracy requirement for a specified interval.
Traceability through Primary Standards
The measurements of indicators, handhelds and other instruments used to calibrate pressure sensors in the field should be traced back to SI units. This unbroken chain of traceability is achieved through the measurements of primary reference pressure standards. These standards' measurements are directly traceable to SI through their country's National Metrology Institute (NMI). Traceability to SI is achieved because these instruments use the primary units, kilogram (kg), meter (m) and second (s) to realize their measurements of pressure. Along this chain of traceability, more and more accurate devices are used to calibrate each successive device. All are ultimately traceable to SI.
Repeatability with a Reference Standard
Another essential aspect in calibration is repeatability. Since these primary reference pressure standards use mass in a gravitational field and a dimensionally stable piston and cylinder system to measure and produce pressure, it’s inherent in their operation that they are consistent and repeatable, when all environmental conditions are accounted for. Primary standards provide uniformity to calibration that ensures repeatability and contributes to the desired level of quality and accuracy to meet each requirement.
From piston gauge to primary reference pressure standard and all the terms in between, what’s important in pressure calibration is providing consistent and reliable readings that meet your accuracy requirements.