Vacuum gauge calibration plays a crucial role in the field of vacuum measurement and is a key supporting tool for the entire research and development of vacuum measurement. Through calibration, not only can existing relative vacuum gauges be unified under reliable standards, but also in-depth research can be conducted on the performance of vacuum gauges in the development stage.
The so-called "vacuum gauge calibration" essentially refers to the "calibration" operation of the relative vacuum gauge. It should be noted that the calibration of a vacuum gauge is carried out under specific conditions for a specific type of gas, from which calibration coefficients or calibration curves are obtained.
Once the gas type changes or the working conditions change, the original calibration curve is no longer applicable and must be recalibrated. Even for the same measuring instrument, if the gauge is replaced, its calibration curve will also change accordingly. It can be seen that calibrating the relative vacuum gauge is not only necessary, but also needs to be carried out regularly, otherwise measurement errors beyond the allowable range may occur.
Calibration is aimed at the overall vacuum gauge, covering both the vacuum gauge as a primary instrument and the electronic circuit as a secondary instrument. Usually, the two are calibrated together, but it is more ideal to calibrate the vacuum gauge gauge and electronic circuit separately.
Vacuum gauge calibration requires a standard vacuum gauge and calibration system, and is achieved through specific methods.
Vacuum standards include absolute vacuum gauges, standard relative vacuum gauges (or secondary standard vacuum gauges), and absolute calibration systems.
All absolute vacuum gauges can serve as vacuum standards. The vacuum gauge calibration system that uses an absolute vacuum gauge as a reference and accurately calculates the regenerated low pressure after pressure decay as the standard is called an absolute calibration system.
For example, the expansion method calibration system applies the principle of static thermal equilibrium, based on the Boyle's law of ideal gases. This system extends the calibration lower limit of the U-tube pressure gauge to high vacuum (10 ⁻⁴ Pa). Vacuum gauges with high stability and accuracy can be used as secondary standards for calibrating working vacuum gauges after calibration. Such vacuum gauges are called secondary standard vacuum gauges. In the field of metrology, standards are a system arranged according to accuracy levels.
On May 1, 1990, the State Administration for Technical Supervision approved and began implementing the important standard "Vacuum Measuring Instrument Calibration System" (JJG2022-89).
With the rapid development of modern technology, significant progress has also been made in the field of vacuum technology. Currently, the range of vacuum acquisition and measurement has greatly expanded, extending from the original atmospheric pressure (10 ⁵ Pa) to a very wide range of extremely high vacuum (<10 ⁻¹⁰ Pa).
However, in actual industrial production and scientific research activities, through extensive practice and statistical discoveries, the pressure range involved by people is mainly concentrated between 10 ⁻⁸ and 10 ⁵ Pa. In this specific pressure range, in order to ensure the accuracy and consistency of vacuum measurement values, the "Vacuum Measuring Instrument Calibration System" has emerged.
This verification system plays a crucial role. It is a key link in ensuring the accuracy and reliability of vacuum measurement values, through which effective transmission of vacuum measurement values can be achieved between different links and equipment.
Specifically, in the field of vacuum metrology, the accuracy of vacuum timing instruments at all levels is crucial for the entire measurement process. The calibration system is like a precise ruler, providing a unified measurement standard for these vacuum timing instruments and enabling strict calibration of various levels of vacuum timing instruments.
And it should be emphasized that the calibration system is mainly targeted at the specific pressure range of 10 ⁻⁸ to 10 ⁵ Pa. Within this scope, whether it is the vacuum standard device used for calibration and testing by the metrology department, the vacuum gauge used in the experimental process by the scientific research department, or the vacuum measurement equipment involved in the production process by the industrial department, they all need to be calibrated according to this calibration system to ensure the accuracy and reliability of vacuum measurement values in the entire industrial production and scientific research process, and to avoid various problems caused by inaccurate vacuum measurement, such as experimental result deviation, unstable production quality, etc.
