Especially in the automotive industry, there is a strong demand to analyze the cleanliness of fluids from manufacturing processes and operation. This is because today's components are subjected to constantly increasing amounts of stress and their function is easily impaired by particulate contamination. In consequence, limiting values for cleanliness levels need to be ascertained and measured. Established analysis procedures, such as normed gravimetric analysis which is used in many standards, are unable to cope with this growing demand. As can take up to several hours to carry out vacuum filtration, oven-dry the analysis filters and weigh residues manually, it impossible to develop shorter control loops to assess cleanliness-relevant production parameters and analyze the rising number of samples. Up till now, no rapid analysis procedure has been developed which conforms with existing gravimetry standards. Such a procedure first needs to be conceived, realized and verified. There are a number of direct techniques for assessing particulate contamination in fluids, ranging from single particle counters functioning by the principle of scattered light right up to integral sensors for measuring turbidity. Indirect techniques, such as determining the blocking of analysis filters by measuring differential pressure, are also used. Most of these techniques fulfill requirements after a short analysis time. However, none of the techniques supply values which are compatible with established standards or a company's annually-expanding database, thus making them only suitable as a basis for developing a new technique. Based on the principle of a filter centrifuge with integrated imbalance sensors, a test bench was designed for the rapid gravimetric analysis of solids in liquids. Different variations were assessed and selected in order to fulfill the requirement profile of a rapid, analysis system which is compatible with current norms. With the test bench, particles are rapidly sedimented using centrifugal filtration, dried thoroughly and the mass of filtration residues are simultaneously determined in a single step. While developing a reliable work method to carry out analysis filtration, adapted data acquisition and data processing were implemented as well as a systematic layout of filtration parameters. This enabled accurate analysis compatible with norms, and proved the suitability of the technique as a testing method. To ensure fulfillment of the requirement profile developed, the filter centrifuge and analysis methodic were verified with the aid of experimental tests. The verification experiments confirm that the technique using a filter centrifuge fulfils the requirement criteria developed for the gravimetric analysis of particles in suspension. The new technique has a time-saving of up to 90% compared to conventional gravimetric analyses, and can be implemented not only to measure contamination in fluids but also to determine all types of solids. Therefore, the new method forms a solid basis to establish a universal industrial analysis technique.
Filterzentrifuge zur gravimetrischen Analyse von Partikeln in Suspensionen
2010
Hochschulschrift
Elektronische Ressource
Deutsch
Filterzentrifuge zur gravimetrischen Analyse von Partikeln in Suspensionen
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