September 1, 2021
2 MIN READ
All members of the scientific and engineering community require reliable data and results in order to provide excellent quality products and services. The Vacuum industry is no exception. Maintaining a high level of quality, accuracy and precision in the measurements made in vacuum technology is pivotal to providing a trusted service. Calibration is key to this.
Many people confuse calibration with the adjustment or alignment of an instrument in order to make it produce a more accurate reading, whether this is measuring level of vacuum or otherwise. In fact, calibration involves the comparison of an unknown measurement with a known reference. An important aspect of calibration is that all measurements can be traced back to a standard data source.
Atmospheric pressure around the world is around 1013 millibar, however depending on the weather it can fluctuate between 990-1030 mBar. In our industry we attempt to lower the pressure of a container to varying degrees of vacuum. The lowest level is known as rough vacuum (~500mBar) followed by medium vacuum (above 1x10-3 mBar) high vacuum (above 1x10-7) and anything below this pressure is known as ultra-high vacuum.
Unfortunately, no gauge can measure the whole range of vacuum levels, so many different types of gauge are used. However, there are ‘combination gauges’ available, which incorporate more than one class of gauge so that a wider range of vacuum can be measured.
All calibration gauges used here at Leybold have traceability, allowing them to be reliable and accurate. They are finely compared to German National standard reference gauges, which are kept in Cologne. Customers rely on Leybold to supply them with accurate calibration and tracing our calibrations back to these extremely accurate sources provides this.
There are several types of calibration gauges, which all provide different levels of vacuum measurements. Pirani gauges, invented in 1906 are less accurate, with a percentage error of around 15-20% and tend to be used for lower levels of vacuum. Capacitance gauges are useful down to a pressure of 1.33x10-5 and are highly accurate in comparison to Pirani devices, with a percentage error of less that 1%. Higher levels of vacuum require more specialized equipment, such as Ionization gauges. These can measure extremely low pressures (down to 1.33x10-10) at a percentage error of 10%.
Customers trust Leybold to provide quality service and deliver precise data. The calibration gauges we use allow us to maintain high standards of accuracy for our clientele with UKAS ISO 9001 accreditation, but also allow us to trust our own results. Calibration may appear to be an inconsequential routine task, but in fact it is the cornerstone of all scientific research, ensuring that we produce dependable, rigorous and cutting-edge results.
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