NIST Standard for CO2 Monitor Calibration

[mguilbert]

Good Morning,

I have a quick question. Is there a NIST standard for Carbon Dioxide monitors ie it actually reads CO2 ppm in air?

Thanks,

 

[Jim Wynne]

Re: NIST CO2 monitor calibration

Have a look at this page for some general information about CO2 meter calibration. I'm not sure what you mean by "NIST standard." Meters can be calibrated by accredited labs, but as you can see by the page I linked to, I don't think you'll find a "master" as such. The meter must be exposed to some sort of known gas source, and which source is used depends on the criticality of the measurements.

 

[mguilbert]

Thanks,

The reason I needed to know if a NIST existed is because of ISO 9001 Clause 7.6 a). It did not believe this could be NIST traced so we can used the manufactures of the devices proceedure using span gas technique.


Thanks again this came up in an audit.

 

[Hershal]

It appears you are seeking traceability of a gas monitor's (aka sniffer) calibration. There are often two parts to this. One is electronic, but that is rarely touched in the field. The other is gaseous. That, as the page from Jim makes clear, relies on certified gases. That is where your true traceability lies. So, traceability may be through Sweden as an example. That is a non-issue as they are CIPM Signatories.

Now, for the calibration itself, you should have an accredited lab - with gas calibration in their scope - actually perform the calibration. Sounds easy, but is harder than it sounds as there simply are not that many labs with gas. Still, that is how you get the documentation of the traceability, and the uncertainty.

 

[mguilbert]

What we are currently using is certified gases and calibrating according to manufactures instructions. If the span gases are certified is that not enough or do we need to do more. The standard states in 7.6.a: "...where no such standard exists, the basis used for calibration or verification shall be recorded".

Thanks again this came up during an audit.

 

[Hershal]

You may well be in good shape, so long as you keep the certificates of analysis, and have at least taken a stab at the uncertainties. Those two things should establish the traceability back through a NMI (National Metrology Institute).