In this paper, the mechanical properties of continuous glass fiber reinforced glass fiber reinforced plastic (GRP) are studied experimentally at first, and the design points of GRP pneumatic ball valve are derived on the basis of known GRP material performance parameters.
3. Pneumatic ball valve materials are mainly made of epoxy resin and phenolic resin (including its modified varieties, such as polyvinyl butyral modified phenolic resin, xylenoldehyde modified phenolic resin, epoxy phenolic resin, etc.), which are currently used to manufacture valves in China. Polyacetate glass fiber reinforced plastic valves and modified xanthan resin glass fiber reinforced plastic valves are also produced in a small amount. The glass fiber as reinforcement material has different forms, but limited to the molding process, it is mainly reinforced by chopped fiber.

What is the content of measurement?
The measurement content of electromagnetic flowmeter can generally be summarized in the following six aspects: measurement unit and unit system: measurement instrument (or measuring instrument), including the realization or realization of measurement benchmark and measurement standard, working measurement instrument of measurement unit: large measurement value, tracking source, including verification, calibration, test, inspection and test: physical constant, Measurement of materials and material properties: measurement uncertainty, data processing, measurement theory and methods: measurement management, including measurement assurance and measurement supervision. The function of electromagnetic flowmeter is to produce uniform DC or AC magnetic field. The DC magnetic circuit is realized by permanent magnet, which has the advantage of simple structure and less interference from AC magnetic field, but it is easy to polarize the electrolyte liquid in the measuring tube, so that the positive electrode is surrounded by negative ions, and the negative electrode is surrounded by positive ions, that is, the polarization phenomenon of the electrode, and causes the internal resistance between the two electrodes to increase, thus seriously affecting the normal operation of the instrument. When the pipe diameter is large, the permanent magnet is also large, bulky and uneconomical. Therefore, the electromagnetic flowmeter generally uses an alternating magnetic field and is excited by a 50HZ power frequency power supply. Vortex flowmeter is characterized by small pressure loss, large range and high accuracy. It is almost unaffected by fluid density, pressure, temperature, viscosity and other parameters when measuring volume flow under working conditions. There are no movable mechanical parts, so the reliability is high and the maintenance is small. The instrument parameters can be stable for a long time. The vortex flowmeter adopts piezoelectric stress sensor, which has high reliability and can work in the operating temperature range of - 20 ℃~+250 ℃. With analog standard signal and digital pulse signal output, it is easy to use with computer and other digital systems. It is an advanced and ideal measuring instrument. The steam flowmeter is mainly used for flow measurement of steam medium fluid in industrial pipelines. The steam flowmeter is characterized by small pressure loss, large range and high accuracy. It is almost unaffected by fluid density, pressure, temperature, viscosity and other parameters when measuring the volume flow under working conditions. There are no movable mechanical parts, so the reliability is high and the maintenance is small. The instrument parameters can be stable for a long time.