Microbiological Assessment of Compressed Gases in Pharmaceutical Facilities

Sandle, T. (2015) Microbiological Assessment of Compressed Gases in Pharmaceutical Facilities, Journal of Validation Technology, Vol. 21, Issue 2, August 2015, pp1-8 Microbiological assessment of compressed gases in pharmaceutical facilities Tim Sandle Introduction Compressed gasses are used at different stages of the pharmaceutical manufacturing process. Applications include weighing of vials on process line or the removal of fallen vials. Furthermore, compressed gases such as air, nitrogen, and carbon dioxide are deployed in operations involving purging or overlaying. Compressed gas sampling for microorganisms is an important part of contamination control assessment (1). While sampling is important, the method of sampling can hindered by the design of the gas system, where sampling is not easily conducted in an aseptic manner, or by the design of the air-sampling instrument. This paper reviews the important aspects of compressed air sampling for microbiological assessment and looks at possible sources of contamination, should microorganisms be recovered. Compressed gas Compressed gas is a general term for gas stored or held under pressure that is greater than atmosphere. Gas is compressed via a compressor; here, the greater the quantity of the gas then the higher the pressure is (degree of compression). The compressor takes gas or air, which occupies a given space, and reduces it to a smaller space. Here the greater mass of air or gas produces a greater pressure. For instance, compressed air operating at 100 pound-force per square inch will have been compressed down to 1/8th of its original volume. 100 pounds per square inch equals 7 bar; or, to use SI units, one pound per square inch equals approximately 6894 Pascals). Types of compressed gas include air, which is colorless and odorless, where the composition is 78% nitrogen, 21% oxygen, and the remainder composed of trace elements. Other common gases are oxygen, carbon dioxide and nitrogen. Aside from air, nitrogen is the most commonly used gas in the pharmaceutical sector. Nitrogen has inert characteristics that lead to its ideal use as a pressurizing agent. With this, tanks, pipelines, hoses, vessels, and other process equipment can be tested for leaks with nitrogen gas. Nitrogen gas can also be used to dispense or transfer most fluids from storage tanks or reservoirs. Nitrogen gas should be composed of a minimum of 99% nitrogen gas, with trace impurities, like carbon monoxide, carbon dioxide and oxygen permitted at