SAMPLING WITH LABORATORY ANALYSIS
to ensure the compressed air quality, it is absolute necessary to monitor the important parameters. apart from dew point as a critical dimension, the RESIDUAL OIL CONTENT or OTHER IMPURITIES play a vital role. many production processes depend on clean, treated compressed air, without TRACES OF IMPURITIES, for example, in pharmacy, chemical industry, food industry or semiconductor manufacturing. the residual oil plays an important role, specially in the distribution mechanisms. if the oil content rises over the critical level, for example, because of incompletely filtered aerosol, the complete plant gets contaminated in a very short time. Since the oil has a very low vapour pressure, it takes relatively long time to bring back the plant to completely „oil free“ condition. moreover, the cleaning of pipeline network choked with oil causes very high costs.
with the sampling set of PRO air, the compressed air users can themselves carry out the sampling. the individual steps are also explained in detail. all necessary components for a precise and reliable measurement are covered in the (rental) set: the specially developed, pressure resistant tube holder, a test tube, all connections and hoses, a measuring instrument for determination of the ambient parameters and even hand gloves and goggles.
after connection to the pipeline network, the test tube is flown through with pre-defined parameters and impurities present in the carrier gas get accumulated in the sorbiens of the sampling tube. in the enclosed return envelope, the sample is to be sent to an affiliated accredited laboratory through PRO air. a recently developed GC-FID-measuring procedure is similar to the H53-method for the detection of hydrocarbons in the range of C6 to C40 or with the help of mass-spectroscopy the presence of other contaminants can be examined.
BACKGROUND INFORMATION
in 2001, this method replaced the till then valid standard (DIN 38409 H 18) for determination of mineral hydrocarbons with the help of IR-spectroscopy. Since 2001, now the only valid standard DIN ISO 9377-2 (formerly DIN 38409 H 53) is used. the laboratory measurement is done conforming to the standard 8573-5:2001. the IR spectroscopy is replaced by a method carried out with the help of gas chromatography. hydrocarbons of known chain length which act as a marker (e.g. C10 and C40) are included. finally the overall surface between the marker peaks are integrated.