Periodic calibration: How often do the devices need to be calibrated?

In principle, the user himself determines the calibrating interval. People often use one per year or in case of very clean gas, one per 2 years. The following questions/points can be helpful:

  • How important is it to maintain the accuracy of the measuring device?
  • What is the maximum allowable deviation?
  • Can the user determine the deviation of the measuring devices himself by means of a reference?
    Prior to installation into the system, the actual state is detected by means of a reference device. The customer determines the periodic inspection himself. It is important to make sure thereby that the measuring setup is always the same.
  • Internal or external specifications determine the interval:
    Is a periodic calibration from an accredited body required (e.g. Dakks (previously DKD) or SCS)?
  • Is the actual state determined prior to a recalibration?
    Yes, provided that the measuring device works, the current deviation is determined. A report is generated thereby. If it lies outside of the device specification, the measuring device is readjusted (adapted to a reference).

We suggest the following calibration interval:

1. First inspection after one year
2. After several calibrations have been made in succession, the deviation of calibration to calibration must be evaluated. Based on these data, a decision can be made to adapt the calibrating intervals.

The following influences can lead to an increased deviation:

1. No stable flow, caused by pulsating pumps, e.g.
2. The gas condenses or carries along liquid or dusty particles (applications with ambient air are particularly susceptible to contaminations. A filter needs to be provided here).
3. The effective pressure deviates considerably from the calibrated pressure (+/- 0,2%/bar).
4. The gas/gas mixture is not consistent with the calibrated gas.
5. The aging of electronic components can cause changes, sometimes even improvements. Electrical changes appear as a result of aging or gradual burning of components, which impact the quality of the output signal.