2 Analysis: At present, the matrix resin of FRP pneumatic ball valve materials in China is mostly modified phenolic resin, and the reinforcing fiber is generally chopped fiber. This kind of FRP pneumatic ball valve can only be used under the working condition of PN6, which greatly limits the scope of application and makes the excellent corrosion resistance of FRP not be allowed to play. In order to meet the growing demand for valve use in various industries and the needs of various harsh service environments, the existing FRP valve materials and manufacturing processes must be improved to make it suitable for higher pressure ranges.

1、 The cause of the fault is that the zero point is unstable. The human body can be summarized into five fault causes, which are:
(1) The pipeline is not full of liquid or the liquid contains bubbles;
(2) Subjectively, it is considered that the liquid in the pipeline system has no flow but actually has small flow; In fact, it is not enough for the electromagnetic flowmeter to fail, but it is enough to accurately reflect the misunderstanding of flow conditions;
(3) The sensor grounding is not perfect and is subject to external interference such as stray current:
(4) Reasons for liquid (such as liquid conductivity uniformity, electrode pollution, etc.);
(5) The insulation of signal circuit drops.