A beverc copper corrosion process in the water distribution system of a County Hospital has been detected in the cold and warm water sections shortly after the opening of the Hospital.The damaged coppcr pipes showed pitting corrosion phenomena that could not be attributed to known types of pitting. The results of a first sampling revealed the same kind of corrosion in all installation areas. A thorough examination of the samples (perforations and hole depths) proved an influence of design and operating con& tions o n the extent of corrosion.
A coppcr corrosion process of unknown origin in a county hospital in Germany has been ohservcd in the cold and warm watcr supplics shortly aftcr operating the hospital. It seemed that the cause of these damages could he attributed t o microbially induced corrosion. Thc evaluation o f damages indicaled that the constructive design of the installations and the operating conditions arc paramctcrs influcncing the pitting corrosion to a large extent. In the past other damages have occurred in this water distribulion area already [ 11.Two test rigs have bccn installed in the county hospital to simulate the corrosion process and to get a profounder understanding of the corrosion mechanism. The results obtained from these tcst rigs are compared to the findings in the hospital a few years ago concerning corrosion of copper as well 21s analytical, biological and operational parameters.K i m nach dcr Eroffnung tratcn in den Kaltund Warnivrasserbcrcichen in cincm Krciskrankcnhaus in Deutschland Kol-rosionsschaden unbekannter Art auf. Die beschadigten Kupferrohre zeigen 1,ochPraM. der den bis heule bekannten Lochkorrosionserschoinungen an Kupfer nicht zugeordnet werdcn kann und bci clcm offcnsichtlicli Mikroorganismcn cine wcscntlichc Rolle spiclen. Eine eiiigehende Schadensanalyse zeigt. dal3 sowohl die 1nsta.llalionsals auch die Betriebsbedingungen wesen~lichc EinfluBpxamctcr sind. Im gleichcn Wasser\.crtcilungsgcbict traten in dcr Vcrgangcnheit ahnliche Schadcnsfalle auf [ 11. l m Kreiskrankenhaus wurden zwei Versuchsstaiide installiert. urn den KorrosionsprozeB nachzustellen und mehr Einblick in den vorliegenden Korrosionsmechanismus LU bekommeii. Die Erj;ehnisse, die nach zwci Jahrcn Betriebsdaucr in dicscn Vcrsuchsstanden crhalten wurdcn, werden mit deli Scliadensbefunden aus dem Krankenhaus vor einigeii Jahren hezuglich der Korrosionserscheinungen an Kupler verglichen. Dabei werden analytische. biologische und operative Parameter bcriicksichtigt.
Diffusion coefficients are reported for dilute aqueous solutions of sodium alginate, and for three compositions of the ternary system comprising of sodium alginate/sodium chloride/water at 20°C applying the conductimetric method. From binary transport data the ternary diffusion coefficients for alginate of added salt (NaCl) can be qualitatively calculated. Due to electrostatic interactions between the ions the diffusive flow of the alginate polyelectrolyte and added salt reveal strong coupling. At pH>5.0 (20°C) and ionic strength of 0.015 M NaCl each mole of diffusing alginate cotransports approximately 210 moles of NaCl. Coupled flow of NaCl ceased if the solution pH is approaching pH 5.5, close to the isoelectric point of alginate (pH 5.4). Between pH 4.5–5.0 the coupled transport of NaCl is governed by the diffusion of the protonated alginate concentration gradient due to the diffusion induced electric field along the neutral alginate. At acidic pH (3.5–4.0) diffusing alginate generates a counter flow of NaCl due to additional bound protons, yielding a net positive charge hence the D21‐value is large and positive.
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