A typical example for the need of quality control, e.g. “good/ bad” evaluations, is the testing of products made of plastics. In this case our customer´s specimens are used in fuel systems in the automotive industry. For the quality control testing, we developed a bursting unit with an EPK 60 unit.
An important test parameter is the adherence to burst pressures, in this case specified with 15 bars. During the test this specified burst pressure is far exceeded (up to 40 bar). The PC operated pressure regulator EPK fills each specimen with pressure, hold the pressure by closing the shut-off valve or using the “controller-off” function and measure then a pressure increase or drop over time depending on the specimen properties.
The test procedure is defined as a type test specification in the software. The test will be started at a minimum pressure of 10 bar. After reaching the respective set pressure and after a short settling time, the pressure is hold (separation valve) and every 3 seconds a value is recorded.
As soon as 5 values are monitored (after 15 seconds) and if these do not derivate more than ± 0.5 bar, the valve will be opened and the set pressure is increased by 5 bar (now 15 bar) and so on.
From the absolute or relative pressure change you can read the degree of plastic deformation over the time.
The test ends with the reaching of the setted final pressure (40 bar) or with the bursting of the specimen. In a customer test case for example, the specimen started to leak after 6 seconds at a pressure of 40 bar and further bursted after a very short time.
The software is recording the graph of the pressure curve. Together with tables for the pressure measurements it can be printed or saved to disc for further statistical evaluation.
For all burst tests it is mandatory to ensure the safety and user protection during the whole test. The test environment has to consider the pressure and volume of the specimen and has to offer enough space around the specimen within. Monitored door contacts or locking systems can be controlled also with the EPK.
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