•Even 22 percentage points increase in retention was achieved by precompaction.•Only small increase in pressure was needed to compensate the caused capacity decrease.•Cellulose membrane structure ...effects significantly on irreversibility of compaction.•Compaction of all the tested membranes was not affected by temperature increase.
Compaction of a polymeric membrane results in a denser membrane structure with increased hydrodynamic resistance, which may positively affect the retention factor. This raises the question of whether membrane compaction could be a cheap and simple way to enhance membrane performance. In this study, compaction and retention data of four different commercial polyethersulphone and regenerated cellulose membranes were examined to gain insight into how membrane retentions could be improved with compaction at different temperatures. Although there was enormous variation in both the reversible and irreversible compaction of the membranes tested, retention in all membranes clearly increased after compression under 7bar and 50 or 70°C conditions. For instance, polyethylene glycol (PEG) (8kg/mol) retention of a 30kg/mol membrane increased even by 22 percentage points, up to 97%. This study demonstrates that it is possible to easily modify retention values of commercially available membranes, thereby increasing their usability in different applications.
•A novel UTDR tool is used in on-line monitoring of membrane compaction.•Significant differences were found in compaction tendency of different membranes.•It seems that both the selective skin layer ...and the layers below the skin layer compact.
This study evaluates differences in reversible (after relaxation) and irreversible compaction and the effect of compaction on the performance of three different ultrafiltration membranes. The evaluation is based on results from both off-line and on-line measurements of compaction. The on-line measurements were done with an ultrasonic time-domain reflectrometry (UTDR) tool with improved resolution compared to tools used in earlier studies.
The results reveal that the regenerated cellulose membrane compacted significantly more than the tested polyethersulphone membranes. This dissimilarity originates from the different membrane materials used and from significant differences in the membrane structures. It is also found that measurements of membrane compaction, whether made on-line or off-line, are not predictive for membrane performance. For instance, compaction of the UH030 membrane was negligible but its permeability decrease and retention increase due to the compaction were significant. Compaction decreased the cut-off values of the 30kDa membranes to lower than 8kDa. The results thus indicate that the skin layers of the membranes compact significantly causing remarkable changes in membrane performance. Thickness changes occurring in the scale of skin layer thicknesses are out of the resolution limits of methods thus far available for monitoring of membrane compaction in real-time. Real-time measured information on compaction phenomena is further needed to be able to distinguish flux decrease caused by concentration polarization and the effects of reversible compaction.
Testing of manufacturing faults of CMS RPC link boards Korpela, A.; Karjalainen, A.; Tuuva, T.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2010, Volume:
617, Issue:
1
Journal Article
Peer reviewed
A test board suitable for mass testing of the production of CMS RPC link boards has been developed. The test board provides a fast first-level pass of the link boards at the production facility. This ...ensures that link boards with basic errors are not sent further to the long-term tests at the laboratory. A Field Programmable Gate Array (FPGA) circuit is used to scan connections and shorts of the board traces. The test board functioned well and provided a fast, less than 1
min per board, test at production.
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