The manufacturers of raw materials must have a creep failure curve that meets the standards of plastic pipeline products; at the same time, the sealing test, valve body test, and overall The valve's long-term performance test, fatigue strength test and operating torque are all stipulated, and the design service life of the plastic valve used for industrial fluid delivery is 25 years. Due to the advantages of plastic valves such as light weight, corrosion resistance, non-adsorption of scale, integrated connection with plastic pipes and long service life, plastic valves are used in plastics for water supply (especially hot water and heating) and other fluids for industrial use. It is mainly used for the sealing test of the valve seat and the sealing test of the valve body. d) The seal between the valve stem and the valve body shall comply with EN736-3. The sealing test of the valve seat is to verify the performance of the valve isolation pipeline system; the sealing test of the valve body is to verify the leakage of the valve stem seal and the seal of each connection end of the valve. The way of connecting the plastic valve to the pipeline system is butt welding: the outer diameter of the valve connection part is equal to the outer diameter of the pipe, the end face of the valve connection part and the end face of the pipe are welded relative to each other; the socket bonding connection: the valve connection part is in the form of a socket , Adhesive connection with pipe fittings; electric fusion socket connection: the valve connection part is a socket type with an inner diameter laying an electric heating wire, and electric fusion connection with the pipe; socket thermal fusion connection: valve connection part is a socket form, which is connected with the pipe Perform hot melt socket connection; socket adhesive connection: the valve connection part is in the form of socket, and the socket connection is bonded with the pipe; socket rubber seal ring connection: the valve connection part is in the form of socket with inlaid rubber seal ring , Socket connection with pipe. Flange connection: the valve connection part is in the form of a flange, which is connected with the flange on the pipe; Threaded connection: the valve connection part is in the form of Complete Vacuum Unit Manufacturers a thread, which is connected with the thread on the pipe or pipe fitting; Connection: The connection part of the valve is a live connection, which is connected to the pipe or pipe fittings. The plastic valve must not have internal leakage (valve Seat leakage) phenomenon, there must be no external leakage (valve body leakage) phenomenon. 3 Manufacturing requirements a) The performance of the purchased raw materials should be consistent with the instructions of the raw material manufacturer and meet the product standard requirements. To maintain the same service life, it is necessary to reduce the use pressure. It should be positioned at the end or any position in the middle by friction or the actuator. e) The valve body shall be marked with the codes of different production locations of the producer. b) The sealing part is driven by the valve stem to open and close the valve. f) The applicable flow rate of all valve operating devices should reach 3m/s. Through the discussion of several problems arising from international standards, the producers and users of plastic valves have attracted attention. The types of plastic valves in the world mainly include ball valves, butterfly valves, check valves, diaphragm valves and globe valves. It has formed a statement that plastic valves cannot be used, affecting the overall development of plastic pipeline applications. c) The valve body should be marked with the manufacturer's name or trademark.. 2 Design requirements a) If the valve has only one pressure bearing direction, it should be marked with an arrow outside the valve body, and the symmetrically designed valve should be suitable for two-way flow and isolation of fluid. The main raw materials are ABS, PVC-U, PVC-C, PB, PE, PP and PVDF etc. e) In terms of valve wear resistance, the design of the valve should consider the service life of the worn parts, or the manufacturer should indicate the recommendation to replace the entire valve in the operating instructions. Part 1: Metric Series and ISO 15494:2003 'Industrial Plastic Piping Systems—PB, PE, and PP—Pipe and Pipe Fitting System Specifications—Part 1: Metric Series”. In the piping system, its application advantages are unmatched by other valves. At present, in the production and application of domestic plastic valves, there is no reliable method to control them, resulting in uneven quality of plastic valve products for water supply and other industrial fluids, causing inadequate closure and serious leakage in engineering applications. The position of the fluid pressure cannot change its position.Foreword: Through the introduction of raw material requirements, design requirements, manufacturing requirements, performance requirements, test methods, system application requirements and the relationship between operating pressure and temperature in the standards of international plastic valve products and test methods, we can understand the needs of plastic valves The basic quality control requirements such as the sealing test, torque test and fatigue strength test. c) According to EN736-3, the minimum through hole in the valve cavity should meet the following two points:-For any diameter of the medium circulation on the valve, it should not be less than 90% of the DN value of the valve;-For the structure needs to reduce the medium circulation For a valve with an aperture, the manufacturer should state its actual minimum through hole. The main structural types include two-way, three-way and multi-way valves. 4 Short-term performance requirements Short-term performance is a factory inspection item in the product standard. A valve can have different connection methods at the same time. It is used to check the sealing performance of the plastic valve. With the increasing proportion of plastic pipes in hot and cold water supply and industrial pipeline engineering applications, the quality control of plastic valves in plastic piping systems is becoming more and more important. d) The valve body should be marked with the production date or code. b) The material code, diameter DN and nominal pressure PN should be marked on the valve body. my country's national standards for plastic valves are in the process of being formulated, and its product standards and method standards are based on international standards. The relationship between the use pressure and temperature As the use temperature increases, the service life of the plastic valve should be shortened. In the form of a table, it summarizes the seat sealing test, valve body sealing test, valve body strength test, valve long-term test, fatigue strength test and operating torque requirements for the performance requirements of plastic valve products. In the international standards of plastic valve products, first of all, the raw materials used in the production of valves are required. g) From the top of the valve, the handle or handwheel of the valve should be closed clockwise. The main technical requirements of the international standard 1 The raw material requirements The materials of the valve body, bonnet and bonnet should be selected in accordance with ISO 15493:2003 'Industrial Plastic Piping System-ABS, PVC-U and PVC-C-Pipe and Pipe Fitting System Specification-No
