PPM GAS TO PERCENT VOLUME 2

[wabiz]

I've a tank of C02 gas thats reads 1000ppm CO2.Is that equivalent to .1 percent or do I need to convert it to molecular weights of both gases Nitrogen and CO2 and use another formula?

 

[Montemayor]

wabiz:

What you report is just yet another case of incompetance in engineering. You should have been advised as to whether the "ppm" is in parts per million, volume or in parts per million mass.

It makes a big, big difference on which one your data is based on. Usually, but not all the time, it is a custom to report ppm impurities as ppm(v) or ppmv - which is parts per million, based on the volume composition of the gas at so-called "standard" conditions (yet another avenue for lazy and incompetant engineers to take by not advising the basis for the standard conditions taken). But no one can be certain of the units if the reader of the instrument doesn't take note - or worse (as is sometimes the case) the instrument doesn't state WHAT it is based on.

You are correct in your conversion to %:
1,000 ppms represents (1,000/1,000,000)*(100) = 0.1 %

However, it doesn't tell you WHAT kind of % you are reporting: volumetric or mass?

It it vital to identify what kind of ppm you have before you are able to convert to any other type of expression for concentration of the impurities in the CO2. Sorry, but this is just another example of why engineers have to be specific in what they state or write. If you don't, it leads to mistakes and errors - besides leaving you in the dark about what the data represents.