精密气体质量流量计和控制器

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

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