Calibration Systems
Calibration systems for vacuum gauges
In view of increasingly stringent quality assurance requirements where the accuracy and reproducibility of the vacuum measured during production and service work is essential as well as the vacuum gauges required for this, the demand for calibration systems is steadily increasing in the market place. In critical processes, the accuracy of vacuum measurements is important for process stability, quality and for monitoring these processes. The pharmaceutical industry requires precise vacuum measurements for safeguarding its high quality product. This is the case particularly in freeze drying expensive drugs. For this reason, regular calibration of vacuum gauges is required. This also applies for final vacuum measurements on vacuum systems in service applications in line with factory or international standards.
To cover the majority of applications, Pfeiffer Vacuum has developed two calibration systems - Basic and Pro system.
Calibration system Basic
- For static and dynamic calibration
- Calibration range 1.013 – 10-4 hPa
- Easy to use
- Chamber ISO/TS 3567- compliant
- Up to 3 reference gauges for medium accuracy
- DAkkS-certified reference gauges
- Flexible
- We also deliver customized solutions
Calibration system Pro
- For static and dynamic calibration
- Calibration range 1.013 – 10-4 hPa
- Easy to use
- Chamber ISO/TS 3567-compliant
- Up to 5 reference gauges for high accuracy
- DAkkS-certified reference gauges
- Flexible
- We also deliver customized solutions
Applications
- Freeze-drying in the pharmaceutical and food industry
- Coating systems for optics, ophthalmics, decorative coatings, diffusion barrier layers for PET bottles and packaging films, wear protection coatings for tools, etc., incorporating the use of multiple measuring instruments.
- Final vacuum measurement in pump production and service workshops
- Process monitoring and process control for determining the end of the process, in order to produce consistent quality and minimize rejection rates.
Calibration methods
Calibration is based on a comparison of the measurement values of the gauge to be calibrated and the reference gauge according to ISO/TS 3567. The gauge to be calibrated and the calibrated reference gauges are connected to a standardized vacuum chamber (according to ISO/TS 3567, form b) and are exposed to the same vacuum.
There are two basic methods of calibration – static and dynamic calibration. With the calibration systems supplied by Pfeiffer Vacuum, transmitters can be calibrated statically with a measuring range of > 1 hPa as well as dynamically with a measuring range of < 1 hPa.
The calibration accuracy required defines the number of reference gauges needed.
Accuracy profile for the calibrated gauge with 5 reference gauges
During calibration with 3 reference gauges, the following calibrating accuracy is obtained:
- 0.2% accuracy at 1,013 hPa
- 0.8% accuracy at 2 hPa
- 0.2% accuracy at 0.1 hPa
- 10% accuracy at 10-4 hPa
Calibration with 3 reference gauges obtains an accuracy of 0.2 – 0.8% in the pressure range from atmospheric pressure (1,013 hPa) to 0.1 hPa.
The Pfeiffer Vacuum Calibration system Basic is required for this purpose.
Accuracy profile for the calibrated gauge with 5 reference gauges
During calibration with 5 reference gauges, the following calibrating accuracy is obtained:
- 0.2% accuracy between 1,013 – 0.1 hPa
- 1.0% accuracy at 10-3 hPa
- 10% accuracy at 10-4 hPa
Calibration with 5 reference gauges obtains an accuracy of 0.2% in a wide pressure range from atmospheric pressure (1,013 hPa) to 0.1 hPa. It allows precise vacuum measurement over a wide range from 1,013 to 10-2 hPa.
The Pfeiffer Vacuum Calibration system Pro is required for this purpose.
Example of accuracy level of reference and calibrated gauges
| Standard | Unit under calibration |
|---|---|
| p (hPa) | p (hPa) |
| 1,003 · 10-4 | 1,004 · 10-4 |
| 2,001 · 10-4 | 2,002 · 10-4 |
| 4,004 · 10-4 | 4,006 · 10-4 |
| 7,003 · 10-4 | 7,005 · 10-4 |
| 1,001 · 10-3 | 1,005 · 10-3 |
The reference gauges values and the gauges to be calibrated must be determined for every defined pressure. According to ISO/TS 3567, at least 3 measuring points must be taken into account (e. g. 1, 2 and 7 in above table).
The calibration results must be recorded in a calibration certificate in compliance with DKD 6-2 of the German Calibration Service (DKD) and be kept as proof of this. The user decides whether the deviations from the reference values are admissible. The deviations shown in the above table are sufficiently accurate.
