Specialty gas

Specialty Gases. The specialty gases are generally more reactive than the bulk gases and usually have low volume flow requirements in their appHcations. Historically, these have been deHvered almost exclusively in standard compressed gas cylinders. However, as the need for increased quantities has arisen, bulk specialty gas supply systems utilising larger ton-sized containers and tube trailers are being developed. 

Purification of specialty gases can be divided into two areas purification done by the gas suppHer on a bulk scale prior to filling the cylinder or other dehvery container, and purification carried out by the consumer on a point-of-use scale generally just prior to use. 

Point-of-Use Purification. For the user of cylinder quantities of reactive specialty gases, there are only a limited number of ways to remove impurities and obtain high purity. Specialized point-of-use purifiers have been developed that purify small streams of many important reactive gases. Whereas these point-of-use purifiers cannot remove all important impurities, they are usually effective for removing the contamination added by the users gas distribution system, mostly air and moisture. 

One important class of point-of-use processes utilizes a porous polymer containing reactive metals. Variations in the metal and polymer chemistry are made to optimize the process for different gas appHcations. This is an active area of development and purifiers are available for most of the principal specialty gases. 

Specialty Gases. The purity of specialty gases depends on the systems and procedures adopted by the distributors for bulk gas supply and cylinder preparation, filling, and deHvery. The distributors need to foUow strict cylinder selection, preparation, and filling procedures to ensure the quaHty of the products. Most of the precautions taken into consideration in the bulk gases deHvery system are also appHed for specialty gases to eliminate recontamination. 

Special Gases Data Sheet, Airco Rare and Specialty Gases, Airco Industrial Gases Division, Murray Hill, N.J., 1991. 

Specialty Gases and Equipment Catalog, Air Products and Chemicals, Inc., 1990, p. 1. 

Propyne can be purchased from Linde Specialty Gases or Farchan Research Laboratories. Matheson GJas Products sells propyne also, but only in 100-lb. quantities. 

Samsung General Chemicals (South Korea) Scott Specialty Gases SISAS Group (Italy)... 

Scott Specialty Gases Solkatronic Union Carbide... 

Scott Specialty Gases Shell Chemical Showa Denko (Japan)... 

Matheson Tri-Gas Phillips Chemical Scott Specialty Gases... 

Scott Specialty Gases Solvay Flour (Belgium)... 

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