In the machining workshop of a factory, the mechanical seal leakage of the chip liquid conveying pump occurred. When the pump was opened, the rubber seal of the old machine was found to swell, become soft and tear. As shown in figure:
仔细看机封橡胶上有E, 标志，说明原材质是EPDM，熟称三元乙丙橡胶。
Look closely at the machine seal rubber on the E mark, indicating that the original material is EPDM, known as EPDM.
The pump is used to transport the cutting fluid of the machine tool, so the material contains oil, but the rubber material of the machine seal is EPDM oil resistant, so the machine seal has not been used for long, and the mechanical seal is damaged.
所以在选择合适材质时，需要考虑应用工况，是否耐油，耐酸碱，耐高温，等情况。
So in the selection of appropriate materials, we need to consider the application conditions, whether oil resistance, acid and alkali resistance, high temperature resistance, and so on.
