Abstract
A closed tube sampling (CTS) is a sampling method in which the sharp tip of a nozzle goes through the rubber cap of a sample tube and aspirates a part of the liquid in the tube. The purpose of this study is to develop a nozzle that has high durability (requires low insertion load) and produces few rubber chips when inserted through the rubber cap. It was found that the parameter that influences the insertion load most is the angle of the taper. Rubber chip production could be avoided with the combination of an angle smaller than 28.5° at the nozzle chip for smooth insertion and an angle larger than 15.0° at the inside edge for preventing cutting rubber off. Finally, to validate the durability and effectiveness of this shape, the nozzle was subjected to a test in which it was inserted through a rubber plate 50,000 times. Results showed that there was almost no nozzle abrasion nor increase of insertion load.
