Nonflammable Cryogens

TC/MC-338 or TC-341 cargo tanks are used to ship a variety of flammable and nonflammable cryogenic liquids at pressures up to 500 psig (3447 kPa). Liquid hydrogen and... 

Cryogenic milling can be performed in a media mill, in which process a nonflammable refrigerant is used as the liquid medium, and the mill is run at very low temperatures. This would be suitable for heat-sensitive compounds, but removal of the refrigerant from the final product and larger scale concerns would need to be considered. 

Chlorotrifluoroethylene telomer lubricants are used primarily where chemical inertness and nonflammability are required. The chemical industry and the cryogenic gas industry (primarily oxygen) are the major users of these materials. They are used to lubricate all types of process equipment, such as dryers, conveyers, pumps, valves, and compressor seals. Extreme pressure tests using the four-ball method show that they are good lubricants, without any seizure even at an applied load of 800 kg. 

Class 2.2 includes gases that are nonflammable and nonpoisonous. Gases in this subclass can be compressed, liquefied, cryogenic, or gases in solution. Although... 

Xenon, Xe, is a gaseous, nonmetallic element from family eight. It is a colorless, odorless gas or liquid. It is nonflammable and nontoxic at standard temperatnres and pressnres, but is an asphyxiant and will displace oxygen in the air. The boiling point is -162°F, and the vapor density is 05.987, which is heavier than air. Xenon is chemically unreactive however, it is not completely inert. The fonr-digit UN identification number is 2036 for the compressed gas and 2591 for the cryogenic liqnid. Xenon is used in luminescent tubes, flash lamps in photography, lasers, and as an anesthesia. 

Properties Wh. translucent to opaque solid m.w. 400,000-9,000,000 dens. 2.2 useful temp, range cryogenic to 260 C melts to vise, gel 327 C Shore hardness 55-56 tens. str. 3500-4500 psi elong. 200-300% ( break) chem. inert exc. thennal/chem. resist. lowcoeff. of friction high elec, insulation nonflamm. 

Polyamide-imides are thermoplastic amorphous polymers that possess exceptional mechanical, thermal, and chemical- and wear-resistant properties. They are inherently nonflammable, have outstanding electrical properties, and possess enormous temperature stability from cryogenic to 300°C. These properties place polyamide-imides at the top of the price and performance pyramid with polyketones and polyimides. 

All of the precautions necessary for the handling of any nonflammable gas or cryogenic liquid must be taken. For additional details, see Chapter 2 and the compressed gas manufacturer s MSDS. 

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