| Zugriffsnummer | 36249 |
| Dokumenttyp | Konferenzartikel |
| Peer Review | unbekannt |
| Sprache | Englisch |
| Titel | Mechanically triggered ignition at repetitive friction contacts |
| Autor(in); Institution |
Meyer, Lennart; 3.7, Grundlagen des Explosionsschutzes, PTB-Braunschweig
Thedens, Martin; 3.7, Grundlagen des Explosionsschutzes, PTB-Braunschweig
Beyer, Michael; 3.7, Grundlagen des Explosionsschutzes, PTB-Braunschweig
Krause, Ulrich; Otto-von-Guericke-Universität Magdeburg, Germany
|
| Quelle/Jahr | Proceedings of the 11th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions:(2016), 1176 - 1183 |
| Herausgeber(in) |
Gao, Wei
|
| ISBN | 978-7-8937-165-2 |
| Verlag | Dalian: University of Technology, Electronics and Audio-Visual Press |
| Konferenzangaben | 11th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions (ISHPMIE), Dalian, 24-29, July, 2016, China |
| Freie Schlagworte | mechanical equipment ; repetitive friction ; ignition soruce ; hot surface ; incendivity |
| Zusammenfassung | In case of malfunction within machine parts, friction contacts of metallic surfaces may occur and cause the ignition sources "hot surface" and "mechanically generated sparks". By the use of stainless steel incendive hot surfaces can arise even before the conditions for spark formation are achieved. Several previous studies have considered only friction situations with continuous friction. But, in fans, pumps and agitators repetitive friction contacts can be expected. Therefore, the formation of ignition sources by repetitive friction was investigated and has been compared with the formation of ignition sources due to continuous friction. The friction zone is realised via a pin which is pressed with constant contact force onto the sliding surface of a rotating disc. For the modelling of the repetitive contact two variations were used, on the one hand by an up and down movement of the pin, and on the other hand by special friction discs modelling the repetitive friction by its wavelike surface. The friction partners were made of stainless steel (material number 1.4541). Stainless steel heats up very quickly due to its low thermal conductivity and thus represents the worst-case scenario. The processes were recorded with a high-speed camera. The temperature distribution in the friction zone was detected by an infrared camera which has been validated by additional point wise thermocouple and two-colour pyrometer measurements. The experiments were performed with four combinations of relative velocity (1 m/s - 10 m/s) and surface pressure (10 N/mm² - 1 N/mm²), with the same power density of 10 W/mm². The results show that in the case of repetitive friction contacts and otherwise identical test conditions, the temperature development is slower and the maximum temperature reached is lower than in the case of continuous friction. In the case of the ignition capability of the two types of friction, the difference is not as clear. The ignition threshold curves show only a slight difference, and also the power density required for an ignition is only slightly larger. Only the time until ignition is significantly longer for repetitive friction. That means, no distinction can be made in case of a hazard assessment. |
