2 replies to this topic

[SPF]

We are looking at our IR sampling device on site and have noticed that there is a conversion factor of 31.5 from our PPM reading of the gas phase (collected via tubing from the deadspace of a pipe) to give us our PPM value in the liquid phase.

I cannot understand where this 31.5 conversion factor is coming from, can anyone please enlighten me?

Thanks in advance.

[MrShorty]

We are looking at our IR sampling device on site and have noticed that there is a conversion factor of 31.5 from our PPM reading of the gas phase (collected via tubing from the deadspace of a pipe) to give us our PPM value in the liquid phase.

I cannot understand where this 31.5 conversion factor is coming from, can anyone please enlighten me?

Thanks in advance.

My first thought is that it represents the Vapor-Liquid Equilibrium(VLE: specifically K-value) of DCM over rest of the solvent. Except for pure DCM and an azeotropic mixture with DCM, one would expect the concentration of DCM in the gas phase to be different from the concentration of DCM in the liquid phase. Could that be what you are seeing?

[SPF]

We are looking at our IR sampling device on site and have noticed that there is a conversion factor of 31.5 from our PPM reading of the gas phase (collected via tubing from the deadspace of a pipe) to give us our PPM value in the liquid phase.

I cannot understand where this 31.5 conversion factor is coming from, can anyone please enlighten me?

Thanks in advance.

My first thought is that it represents the Vapor-Liquid Equilibrium(VLE: specifically K-value) of DCM over rest of the solvent. Except for pure DCM and an azeotropic mixture with DCM, one would expect the concentration of DCM in the gas phase to be different from the concentration of DCM in the liquid phase. Could that be what you are seeing?

That would seem like a very reasonable explanation, I sort of thought it might be that but was unsure if it possibly had anything to do with a constant that was relelvant to the specific dimensions of the pipe the sample was taken from or some other physical property. Thanks for your help!