| 摘要 |
The present invention relates to plugcocks or stopcocks, and the method of producing the same. The plugcocks are formed of two primary elements a body and a plug or stem member rotatably mounted therein. The plug member has the shape of a cone the bottom base of which is larger than the top base both the body and the plug or stem being in a plastic material. The invention addresses itself to special problems which arise when a plugcock of plastic material is used in permanent liquid food handling and processing installations such as the milk industry. The problems may include the following: action of heat, rigidity, relative deformations and dilatations. The main characteristic is that the body is at least partly manufactured of PVDF (vynilidene fluoride) and the plug of a thermoplastic which has a rigidity which is maintained at 100 DEG C. The plug may be made of polyolefin selected from the group of polypropylene and polyethylene of high density f.i. of PTFE (polytetrafluorethylene).
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