Acetylene grades available

Table 1. Acetylene Grades Available. (Units in ppm (mole/mole) unless otherwise stated)...

Contracts for acetylene-grade carbide are usually based on size and gas yidd specification, and indude penalties for carbide that fails to meet specified gas yidd. The sizes generally available in the trade are based on established U.S. Government specifications. In general gas yidds range from 280—300 L/kg and depend on the screen size of the carbide. The most important standard is the method of expressing gas yidd, which in the United States is at 15°C and 101 kPa (1 atm). Gas impurities are typically 0.05% by volume phosphine, 0.15% by volume hydrogen sulfide, and 0.001% arsine. 

Butadiene is available commercially as a liquefied gas underpressure. The polymerization grade has a minimum purity of 99%, with acetylene as an impurity in the parts-per-million (ppm) range. Isobutene, 1-butene, butane and cis-l- and Zrc//7.s-2-butcnc have been detected in pure-grade butadiene (Miller, 1978). Typical specifications for butadiene are purity, > 99.5% inhibitor (/c/V-butylcatecliol). 50-150 ppm impurities (ppm max.) 1,2-butadiene, 20 propadiene, 10 total acetylenes, 20 dimers, 500 isoprene, 10 other C5 compounds, 500 sulfur, 5 peroxides (as H2O2), 5 ammonia, 5 water, 300 carbonyls, 10 nonvolatile residues, 0.05 wt% max. and oxygen in the gas phase, 0.10 vol% max. (Sun Wristers, 1992). Butadiene has been stabilized with hydroquinone, catechol and aliphatic mercaptans (lARC, 1986, 1992). 

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