How to choose the valve in the water supply network
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Abstract: According to the requirements of water supply enterprises for the use of water supply pipe network valves, from the perspectives of water supply safety, advanced technology, sealing of water flow, authenticity of inspection, reliability of quality, flexibility of operation, reasonable price, After-sales service assurance, the consistency of the scheduled delivery and the establishment of a more complete inspection, reinspection system, put forward the choice of views on the water supply network valve. At the same time, the main problems of water supply valve are also analyzed and discussed with the actual production and the need of using. Keywords: water supply pipe network, valve selection Water supply pipe network is composed of pipes and valves and other pipe accessories, accessories formed. According to a variety of needs (water pipe network, water pressure scheduling and deployment, maintenance and repair of water needs, the old and new pipeline connections, pipeline washing, etc.), the valve must be opened and closed every day. The service life and quality of the valve determine the normal operation of the pipe network, play an important role in the pipe network, we must attach great importance. Because the pipe network is a bridge between the water supply enterprises and the majority of users, it can be said: a water supply enterprise management is reflected in the normal operation of the pipe network; and the normal operation of the water supply network, but also with the valve Life and quality are closely related. The following valve on the water supply network, make a few comments. 1 The safety of water supply does not affect the water quality is an important indicator of the valve selection. The part that the valve contacts with water mainly is the inner side of the valve body, the seal part, the valve plate, etc. At present, the sealing part produced by many manufacturers uses the rubber material. Commonly used rubber materials are NBR, CR or EPDM. These rubbers are synthetic rubbers. In the synthesis process, to add more than 10 kinds of natural rubber additives and anti-aging additives. The final synthesis of rubber can be used for sealing water supply valves, we must look at whether this rubber is non-toxic, is in line with drinking water hygiene standards. As for the valve inside and valve plate and other parts, many manufacturers used the past paint method, only consider the rust problem, regardless of whether the toxic. In practice, we found that: the water supply pipe network, pipe lining corrosion problem is solved, and the pipe network valve is not lined, due to water precipitation and iron bacteria in the water valve cavity and valve plate erosion and deposition, Resulting in some body wall hilly accumulation phenomenon. Not only affects the quality of water supply, but also some of the main reasons for the lax valve. Therefore, we require that all parts that are in direct contact with water should be sprayed with non-toxic paint, it is best to spray non-toxic epoxy powder by electrostatic spraying. When we choose the valve, we should first check whether there is non-toxic rubber and paint certification and inspection certificate, only with the above conditions of the valve, in order to ensure water pollution-free, to ensure water safety. 2 advanced technology Valve production technology continues to evolve, from the old gate valve to the soft seal gate valve, from the original butterfly valve to the butterfly valve, single eccentric, double eccentric flange butterfly valve, hard sealing butterfly valve, from the traditional single Head exhaust valve to the high-speed dual port exhaust valve. So choose the valve should also take into account the advanced nature of the selected valve. However, in the application of new technologies, we oppose the indiscriminate distinction and do not understand the users' actual and collective actions. Instead, we should combine new technologies and new technologies with the needs of users. A good valve is to get it from the user's immediate needs in the actual production. For example: Resin extrusion sealing method, although from the design ideas and factory tests to prove that it does have advantages. However, in actual use, due to the resin material, extrusion resin tools, there is no solution to the user how to use the problem. Users in the use of this valve, you will not appreciate the advanced nature of this valve, features and advantages, but as a normal butterfly valve. Therefore, the valve production should pay attention to its advanced nature, but also pay attention to its practicality. And pay attention to solve practical problems, such as: exhaust valve float material, float shape (spherical or cylindrical) of the exhaust effect and how the life of research. How to prevent the operation of worm gear butterfly valve control (closed over) problems, gear box top crushing problems, switch instructions marked the problem and so on. Therefore, the choice of valve must pay attention to its advanced technology and practicality. 3 Flow of the sealing valve is a sealing valve is the basic requirements. In practice, there are many types of seals, such as soft seals, hard seals, valve plate seals, valve seals, face seals, wire seals and more. No matter what kind of seal form, can not affect the sealing effect. In the past, we used to use a part of the valve plate sealing butterfly valve, in theory, this butterfly valve biggest advantage is that once the sealing ring failure, do not have to disassemble the valve can be replaced online. However, the practical application of water supply enterprises, the advantages of this butterfly valve is difficult to show. Therefore, if the replacement of rubber ring online not only also need to open the pipe at both ends of the valve, the water pipe emptying. At the same time, the replacement of the rubber ring can not be sealed test, can not determine the replacement effect. Therefore, when choosing the valve, we must pay attention to the valve seal, and combined with their actual application, check the valve sealing effect. 4 The authenticity of the test must require the valve manufacturer to provide a true and accurate inspection report. These inspection reports include: â 'raw material inspection - the original iron in the C, Si, Mn, P, S, such as the composition of the ingredients and the quality of coke; â' ¡castings - metallographic test, elongation test, strength test ; ③ seal test - double-sided pump test and multiple switch test; ④ rubber health quarantine report and the coating of health and quarantine reports and so on. Products produced by companies that provide untruthworthy reports can not be used. 5 Quality Reliability Good quality valve ring, reflected in the entire process of valve manufacturing. ①original iron matching; ② sand mold manufacturing; ③ cast iron casting; ④ machining accuracy. Have a more complete set of quality assurance system. The number of valve switching index is of little significance, not necessarily to meet the switch five thousand times more than the test. Because the pipe network valve is not always on. Sometimes, some valves only switch in ten years. In actual work, we found that the positioning screws on the butterfly valve are loose when installed, and some do not have screw thread fasteners at all. 6 Flexibility of Operation Valve operation is flexible is very important. Flexible operation, not only reflected in the choice of which drive mode, but also reflected in the transmission mechanism related parts processing accuracy. For example, in the butterfly valve drive. There are two general transmission - screw nut type and worm type. General screw nut type is characterized by two slow switch, fast in the middle, better operation, but due to the smaller screw moment, the operator is not easy to grasp the operation of the valve opening and closing level, prone to the valve has been closed Still operating screw twist, fracture. The worm-type is generally easy to turn off. At the same time, the sealing of the valve stem of the valve, butterfly valve transmission parts of the matching speed and torque are the most difficult problem of valve operation. Therefore, the choice of transmission mode should be based on the situation of the water supply enterprises, after listening to the views of the operator, with the manufacturers in close cooperation so that the choice of both flexible operation of the valve, but also to meet the needs of use and work. Validity of the price Valve should have a reasonable price, a reasonable price is not necessarily the lowest price. If only pay attention to the lowest price, it is easy to mislead the manufacturers in order to sell their products, competing to lower the price, or even lower than the cost of the product sales, manufacturers in order not to lose money on the inevitable process, materials, jerry-built, produced valves exist With quality problems, used in the water supply network, the ultimate victims or the user himself. Therefore, we must pay attention to the choice of valves, encourage manufacturers to use value engineering principles, strengthen the main functions, remove redundant functions, optimize system functions. Work hard in management, work hard on cost accounting. It should be noted that a reasonable price can be the lowest price, but the lowest price is not necessarily a reasonable price. 8 after-sales service assurance valve in the water supply network, there will be such a problem, some are part of the valve itself, while others are from the external factors of disruption, brutal construction, illegal operation, poor management and so on. But no matter what the reason, the valve problems, will affect the operation of the pipe network, require the cooperation of manufacturers, so the valve needs to choose the valve manufacturer has a good after-sales service guarantee. Once the valve problems, can be rushed to the scene in the shortest possible time, solve the problem as soon as possible. 9 Ordering and delivery consistency Consistency here refers to the production of valve products produced by the valve manufacturers and water supply companies need all aspects of the product requirements are the same. This requires ordering parties and suppliers (water supply companies and valve manufacturers) to work together, not just one of the efforts. First of all, as the ordering party's water supply enterprise, when ordering the valve manufacturer, it must be in writing to the valve manufacturer to make clear technical requirements, the content should include the type of valve, the valve should be implemented in various parts of the technical standards and quality standards , The main technical parameters, the material of each part, the model of the valve, the sealing form, the requirements of the sealing material, the form of the structure, the connection mode and the transmission mode, the technical standards of pressure test and strength test, Torque and rpm, assembly and appearance requirements, delivery time, location, quantity and much more. Valve manufacturers should be based on contract orders and technical conditions, reasonable production, and ensure that the products produced to meet the ordering units (water supply enterprises) the use of requirements, to ensure the consistency of both ordering and delivery. 10 establish a sound inspection and re-inspection system When a water supply enterprises, after many visits, surveys and after a certain range of tests, the final choice of one or several valve manufacturers, to their products issued to allow access to the local water supply market permits After, it means that water supply enterprises and valve manufacturers established between the supply and demand. At the same time, the valve manufacturer to ensure that water supply enterprises secure, reliable water supply also take the corresponding joint responsibility. On the one hand, require valve manufacturers to consistently provide high-quality products in accordance with the requirements of water supply enterprises. On the other hand, in order to ensure the quality, water supply enterprises are required to establish the necessary and perfect regular inspection and reinspection system for fixed-point manufacturers, generally 2 to 5 years. On the designated manufacturers of people, machines, materials, France, Central and other five elements regularly give inspection and evaluation. Water supply enterprises in the factory inspection at the same time, should also be based on the unit's use of the valve, the original technical conditions necessary amendments and additions.