Phases of hydrocarbons in a compressed gas cylinder

[temaire]

I'm currently in the process of selecting gas mixtures to calibrate a gas chromatograph. One of the gas mixtures I'm interested in has the following composition by percent volume:

methane (CH₄): 95%
carbon dioxide (CO₂): 1%
butane (C₄H₁₀): 1%
acetylene (C₂H₂): 1%
nitrogen (N₂): 2%

The gas cylinder pressure is 1345 psig. I plan on calibrating the gas chromatograph at room temperature (24^oC) and need to ensure that all compounds in the cylinder are in gas phase. I know that the CH₄ and N₂ will be in gas phase since their critical temperatures are well below room temperature. However, I'm unsure about whether the CO₂, butane, and acetylene are in liquid or gas phase. For example, CO₂ has a critical point of ~ 31^oC and 1070 psi. Since the gas cylinder will be pressurized above this at 24^oC, will it be in liquid phase? Am I approaching this problem the right way?

 

[Nidum]

Am I approaching this problem the right way?

Depends . Are you going to use the mixture at that pressure or expand down to a much lower pressure for feeding into the gas chromatograph ?

 

[temaire]

Depends . Are you going to use the mixture at that pressure or expand down to a much lower pressure for feeding into the gas chromatograph ?

I will be installing a two-stage pressure regulator on the gas cylinder and the outlet pressure will be below 125 psig. However, I don't think this addresses the issue of some of the compounds in the cylinder remaining in liquid phase. I need to make sure that there isn't any liquid to begin with.