NATA News Archive
- Published: 02 October 2014
Accurate vacuum and low pressure measurements are becoming increasingly important for high-tech manufacturing processes such as vapour deposition and advanced surface modification. In industries such as biomedical devices and food, accurate vacuum and low pressure measurements ensure product quality and safety. NMI has recently established a new facility for the calibration of vacuum gauges at levels of accuracy comparable to the best in the world.
The new vacuum expansion chamber (VEC) standard expands a sample of gas at a known pressure into a much larger volume to generate a lower pressure, the value of which can be calculated from the volume ratio. Repeating this process allows NMI to generate pressures down to 1 mPa (10 8 atm) with uncertainties as low as 0.2 %. The capability has now been NATA-accredited and participation in international comparisons has yielded extremely satisfactory results.
Although the principle of the system is simple, achieving the result with low uncertainties is a real challenge. For example the dead-volumes in tubing, valves and gauges and the temperature of the gas sample (and all the chamber walls) need to be well understood. As practitioners in the vacuum industry will know, the ‘out-gassing’ of walls, water adsorption and trapped volumes are major challenges, requiring NMI to develop a test method to address them.
Ensuring that your company has full control of the quality and efficiency of their manufacturing processes requires both accurate and reliable measuring equipment and the skills to maintain and use them. Learning by trial-and-error is just not an option in the biomedical field where safety is critical or in high-value manufacturing sectors.
NMI’s upcoming pressure measurement course (covering mPa to MPa) provides the opportunity for you and your staff to understand the underlying principles and appropriate use of a range of commercial instrumentation. The course includes valuable practical skills and tricks-of-the-trade we have picked up while establishing standards like the VEC. It also gives examples for data analysis and uncertainty estimation, and includes a formal evaluation that you can use to demonstrate your competency to auditors.
NMI runs similar courses for a wide range of other measurements, and we will tailor a measurement course or consultancy to your company’s specific needs and deliver it at your work place. Contact us for more information or to discuss your specific needs.