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How often to calibrate a CO2 analyzer considering the Zero drift limit

Hi everybody

This comunity is a great source of knowledge and I hope you guys could help me.

We have a CO2 gas anayzer and I'd like to now how often do I have to calibrate it

This analyzer  reaches a zero drift equal to 5% of the SPAN in 15 days. The range of this analyzer is 0-500 ppb

I'd like to know if there is any international protocol (ISA, ISO) for zero drift limits for CO2 gas analyzers.

Thanks in advance

Diego

• "CO2"
• "GAS"
• "Analyzer"

dbarrigac

• 26 Jun 2015 8:21 PM
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1 Reply

• Michael Kamphus

  

  • 1 Jul 2015 7:08 AM

  Diego,
  from my mind I do not recall an international protocol for zero drift. First I would check manufactures specification on zero drift. The manufacturer will also have a recommendation for zero calibration interval. For such low ranges it could be daily zero calibration or even shorter intervals. Another approach would be to define the zero calibration interval yourself with respect to your CO2 limit alarm. The drift within your selected calibration interval should be so low that you still have confidence in your limit alarm. Let's say your limit is 50 ppb. With 5% fs zero drift in 15 days, it would be 25 ppb for positive drift and 75 ppb for negative. I guess this is not acceptable. If you do daily calibration you either have 48.3 ppb or 51.7 ppb. This may be acceptable.
  Hope this helps,Michael

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