Liquefied compressed gases specifications

Gases in the nonflammable, liquefied compressed gas category include carbon dioxide, nitrous oxide, and others. Liquefied gases must be filled by weight, not by pressure. Note that this section does not apply to Specification TC/DOT-4L cylinders. 

Synonyms Mercaptomethane Methanethiol Methyl sulfidrate Thiomethyl alcohol Chemical Formula CHjSH (ii) Observable Characteristics — Physical State (as shipped) Liquefied compressed gas Color Colorless Odor Garlic foul strong offensive (Iii) Physical and Chemical Properties — Physical State at 15 C and I atm. Gas Molecular Weight 48.1 Boiling Point at I atm. 43.2, 6.2, 279.4 Freezing Point -189, -123, 150 Critical Temperature 386.2, 196.8, 470.0 Critical Pressure 1,050, 71.4, 7.25 Specific Gravity 0.892 at 6 C (liquid) Vapor (Gas) Specific Gravity 1.66 Ratio of Specific Heats of Vapor (Gas) 1.1988 Latent Heat of Vaporization 220, 122, 5.10 Heat of... 

T-C is the interface between gas and liquid. Each point on the line corresponds to a certain temperature and the pressure needed to liquefy the gas at this temperature. Point C is the critical point. Beyond the critical temperature, a gas does not liquefy under increasing pressure. Instead, it is compressed into a supercritical fluid. The critical point is substance-specific. Table 3.2 shows the supercritical conditions of some selected solvents. 

This chapter describes and illustrates the major types of containers used to transport and store compressed gases, including those liquefied at very low or cryogenic temperatures. To keep pace with developments in the industry, CGA, through its technical committees, continually reviews and recommends changes to existing container specifications promulgated by the U.S. Department of Transportation (DOT) or Transport Canada (TC). Moreover, new specifications for compressed gas containers are also proposed from time to time. 

Cylinder valve outlet and inlet connections, cylinder ancillary equipment connections, transfer connections, and regulator connections have been standardized by the industry for the handling of specific types of compressed and liquefied gases and to prevent the misapplication of these potentially hazardous materials. Users of compressed gases are cautioned not to tamper with or replace connections supplied by an authorized gas supplier. 

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