Carbon dioxide equivalent of carbon dioxide. Equivalent (e) is the concentration of that would cause the same level of radiative forcing as a given type and concentration of greenhouse gas. Examples of such greenhouse gases are methane, perfluorocarbons, and nitrous oxide. e is expressed as parts per million by volume, ppmv. Carbon dioxide equivalent Carbon dioxide equivalent (CDE) and equivalent carbon dioxide (e and eq) are two related but distinct measures for describing how much global warming a given type and amount of greenhouse gas may cause, using the functionally equivalent amount or concentration of carbon dioxide () as the reference. Carbon dioxide
Industrial gas ambient temperature is low enough; this includes ethylene (R1150), carbon dioxide (R744), ethane (R170), nitrous oxide (R744A), and sulfur hexafluoride; however, these can only be liquefied under pressure if kept below their critical temperatures which are 9 °C for CH ; 31 °C for CO ; 32 °C for CH ; 36 °C for NO ; 45 °C for SF. All of these substances are also provided as a "Gas" (not a vapor) at the 200 bar pressure in a gas cylinder because that pressure is above their critical pressure. Other gases can only be supplied as liquid if also