Water content of Halon 1301

[clun]

I hope the expert in here could give me a hand.
I got a Halon 1301 (CF3Br) with water content in ppm for gaseous volumn/volumn and mg-H2O/L.
#1 How do I convert it to ppm by weight?
#2 What's the meaning of letter w in ppm w/w?

Any reference book or web-site is recommended?
Thanks a lot for your help!!

 

[jay165]

I'm not an expert, so I could be wrong but my understanding is that by definition, ppm is a volume measurement (ie, ml/kl). Using the w/w means it is weight over weight (ie, mg/kg). Without the w/w suffix it is assumed to be volume based. As for converting to a weight basis, you could look up the densities of the components at the T and P conditions you're interested in and convert from volumes to weights.

 

[TD2K]

ppm can be on a volume, mass or mole basis. For gases, mol and vol percentages are typically taken as equal unless they apply to pressure and temperature which compressibility factors for the two (or more) components must be taken into account. For liquids and solids, mol%, vol% and mass% are all different. Athough there are conventions which 'typically' applies to a specific phase, one should always define it to be unambigious.

For Freon which the water is reported in mg/L, the mg is the number of milligrams of water per litre of either dry Freon or total liquid (water plus Freon). You really need to talk to the lab that did the testing to understand what basis they are referring to but if the water content is low, the difference between mg H2O per litre of dry Freon or 'wet' Freon will be insignificant.

Convert a litre of Freon (which ever basis you use) to mass and you can determine, on a mass basis the ppm for the water content. Similarly, you can convert to determine on a vol% or mol%. Crunch the numbers both way to see the difference.