Atmosphere manufacturing process

Twelve oxygen grades are defined by the Gas Specification Committee of the Compressed Gas Association (CGA) (24), 10 of which are given in Table 4. The contaminants identified relate to possible residues from the atmosphere as well as particulates or fibers that may have been contributed by the manufacturing process or the distribution system. In addition, government agencies and certain commercial users have developed specifications for individual needs (25). In most cases, these specifications closely parallel the CGA grades. 

Di-ft-octylphthalate may be released to the atmosphere through volatilization of the compound from plastics, as a result of manufacturing processes, and through incineration (Vista Chemical 1992). 

Silica gel is probably the adsorbent which is best known. Small sachets of gel are often included in packages of material that might deteriorate in a damp atmosphere. Sometimes a dye is added in the manufacturing process so that the gel changes colour as it becomes saturated. 

The hydrogen manufacture process is relatively clean. In the steam reforming subprocess a potential waste source is the desulfurization unit, which is required for feedstock that has not already been desulfurized. This waste stream contains oil, sulfur compounds, and phenol. In the partial oxidation subprocess, free carbon is removed by a water wash. Carbon dioxide is discharged to the atmosphere at several points in the subprocess. 

The estimated release of 743,015 pounds (337,026 kg) of chlorine dioxide to the atmosphere from over 100 manufacturing, processing, and waste disposal facilities in 2000 accounted for about 72.7% of the estimated total environmental releases (TRIOO 2002). These releases are summarized in Table 6-1. The... 

Polybrominated Biphenyls. Historically, PBBs were released to the atmosphere during three stages of the manufacturing process, and an estimate of the maximum amount of PBBs expected to be lost to the air during the manufactuie of PBBs in fire United States is available (see Section 6.2.1) (Neufeld et al. 

In most parts of the world the local or national regulator(s) responsible for the environment also have powers to limit the amount of material that may be released from a manufacturing process into the atmosphere or local watercourses. In some cases, where the factory effluent is discharged into a sewerage system, this control may be exerted indirectly via hmits on the eventual release by the sewerage system operator. 

Fig. 3.12 Manufacturing processes for the ferrites (a) atmosphere controlled two step firing (b) usual heat-treatment (in Nj gas). In the hatched regions (1) and (6) in (a), the samples are heated or cooled under flowing N2 gas. In the other regions, Po. has to be controlled to obtain the required oxygen content.

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