Since the pipeline network serves as a bridge connecting water supply companies and users, it can be said that the quality of a water supply company's management is reflected in the normal operation of the pipeline network; and the normal operation of the water supply pipeline network is closely related to the lifespan and quality of valves. Below are some suggestions regarding valve selection for water supply networks. [b]1. Water Supply Safety[/b] Not affecting water quality is a crucial indicator for valve selection. The parts of a valve that directly contact water are mainly the inner side of the valve body, the sealing parts, and the valve plate. Currently, many manufacturers use rubber materials for the sealing parts of their valves. Commonly used rubber materials are nitrile rubber (NBR), chloroprene rubber (CR), or ethylene propylene diene monomer (EPDM). These are all synthetic rubbers. During the synthesis process, more than ten kinds of raw materials and additives such as anti-aging agents are added to the natural rubber. Whether the final synthesized rubber can be used for sealing water supply valves depends on whether the rubber is non-toxic and meets drinking water hygiene standards. As for the inner side of the valve and the valve plate, many manufacturers in the past used painting methods, only considering rust prevention and not whether it was toxic. In practice, we have found that while the corrosion prevention problem of the pipe lining in water supply networks has been solved, the valves in the network lack linings. Due to water sedimentation and the erosion and deposition of iron bacteria in the water on the valve cavity and valve plate, some valve bodies develop hill-like deposits. This not only affects the water quality but is also one of the main reasons why some valves cannot close tightly. Therefore, we require that these parts in direct contact with water be coated with non-toxic paint, preferably using electrostatic spraying to apply non-toxic epoxy powder. When selecting valves, we should first check whether they have non-toxic certificates and inspection certificates for the rubber and coatings. Only valves that meet the above conditions can ensure that the water quality is not polluted and guarantee the safety of the water supply. [b]2. Technological Advancement[/b] Valve production technology is constantly developing, from old-fashioned gate valves to soft-seal gate valves, from the initial butterfly valves to wafer butterfly valves, single eccentric, double eccentric flange butterfly valves, hard-seal butterfly valves, and from traditional single-head air release valves to high-speed double-orifice air release valves, etc. Therefore, the advancement of the selected valves should also be considered. However, in the application of new technologies, we oppose the indiscriminate and haphazard approach of rushing into things without understanding the actual needs of users. Instead, we should combine new technologies and processes with user requirements. Good valves are derived from the direct needs of users in actual production applications. For example, the resin extrusion sealing method, although proven advantageous in design and factory testing, fails to address the user's actual usage due to issues with resin materials, extrusion tools, etc. Users may not appreciate the valve's advanced features and advantages, using it like a regular butterfly valve. Therefore, valve production must focus not only on its advanced technology but also on its practicality. It must address problems encountered in practical applications, such as how the float material and shape (spherical or cylindrical) of an exhaust valve affects its exhaust effect and service life. It should also address issues like preventing over-closing problems in worm gear butterfly valves, gearbox housing breakage, and the labeling of switch indicators. Therefore, when selecting valves, both technological advancement and practicality must be considered. **3. Water Flow Sealing** Whether a valve effectively seals is a fundamental requirement. In practical applications, there are various types of seals, such as soft seals, hard seals, valve plate seals, valve body seals, surface seals, and line seals. Regardless of the sealing method, the sealing effect must be maintained. In the past, we used some butterfly valves with valve plate seals. Theoretically, the biggest advantage of this type of butterfly valve is that if the sealing ring fails, it can be replaced online without disassembling the valve. However, in actual applications by water supply companies, this advantage is difficult to realize. Therefore, replacing the sealing ring online requires not only disconnecting the pipes at both ends of the valve and draining the water, but also making it impossible to conduct a sealing test on the replaced ring, thus failing to determine the replacement effect. Therefore, when selecting valves, it is essential to pay attention to the valve's sealing method and check its sealing effect in conjunction with the specific application conditions. **4. Authenticity of Inspection** It is imperative that the valve manufacturer provide authentic and accurate inspection reports. These inspection reports include: ① Inspection of raw materials—the content of C, Si, Mn, P, S, etc. in the raw iron and the quality of coke, etc.; ② Inspection of castings—metallographic tests, elongation tests, strength tests, etc.; ③ Sealing tests—double-sided pump pressure tests and multiple opening and closing tests, etc.; ④ Sanitary quarantine reports for rubber and coatings, etc. Products produced by companies that provide false inspection reports are unusable. [b]5 Reliability of Quality[/b] The quality of valves is reflected in the entire valve manufacturing process. ① Selection of raw iron; ② Manufacturing of sand molds; ③ Casting of molten iron for castings; ④ Machining precision, etc. A relatively complete quality assurance system is required. The number of times a valve is opened and closed is not very meaningful, and it is not necessary to meet the test of more than 5,000 opening and closing times. Because valves in the pipeline network are not frequently opened and closed. Sometimes, some valves are only opened and closed once every eight or ten years. In our actual work, we found that the positioning screws on butterfly valves were loose during installation, and some did not even have bolt threads.　**6. Operational Flexibility** The flexibility of valve operation is crucial. This flexibility is reflected not only in the choice of transmission method but also in the machining precision of components related to the transmission mechanism. For example, in butterfly valves, there are generally two transmission methods: screw-nut type and worm gear type. The screw-nut type is generally characterized by slow opening and closing at both ends and fast opening and closing in the middle, making it relatively easy to operate. However, due to the smaller torque of the screw, the operator may find it difficult to control the degree of valve opening and closing, easily leading to the screw twisting or breaking when the valve is already closed and the operator continues operating. The worm gear type is generally prone to over-closing. Furthermore, the sealing problem of the gate valve stem and the matching of the rotational speed and torque of the butterfly valve's transmission parts are major challenges in valve operation. Therefore, the choice of transmission method should be based on the specific circumstances of each water supply company, taking into account the opinions of operators and working closely with the manufacturer to ensure that the selected valve is both flexible in operation and meets the needs of use and operation. **7. Price Reasonableness** Valves should have a reasonable price, but a reasonable price is not necessarily the lowest price. If only the lowest price is focused on, it can easily mislead manufacturers into competing to lower prices, even below cost, in order to promote their products. To avoid losses, manufacturers will inevitably cut corners on processes and materials, resulting in valves with quality issues. When used in water supply networks, the users will ultimately suffer. Therefore, it is crucial to encourage manufacturers to apply value engineering principles when selecting valves, emphasizing core functions, eliminating redundant features, and optimizing system functionality. Efforts should be made in management and 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. [b]8 Guarantee of After-Sales Service[/b] Valves used in water supply networks will encounter various problems, some due to the valve itself, others due to external factors such as damage from improper construction, violations, or poor management. Regardless of the cause, valve problems will affect the operation of the network and require the manufacturer's cooperation. Therefore, valve manufacturers need to provide a good after-sales service guarantee when selecting valves. Once a valve problem occurs, the manufacturer should be able to arrive at the site as quickly as possible to resolve the issue. [b]9 Consistency Between Orders and Supply[/b] Consistency here refers to the alignment of the valve products manufactured by the valve manufacturer with the requirements of the water supply company in all aspects. This requires the joint efforts of both the ordering party and the supply party (the water supply company and the valve manufacturer), not just one party. First, the water supply company, as the ordering party, must submit clear technical requirements in writing to the valve manufacturer when placing an order. These requirements should include the type of valve, the technical and quality standards to be followed for each part of the valve, key technical parameters, materials of each part, valve model, sealing method, requirements for sealing materials, structural form, connection and transmission methods, technical standards for pressure testing and strength inspection, requirements for corrosion protection and lining, maximum torque and rotation speed, assembly and appearance requirements, and delivery time, location, and quantity, etc. The valve manufacturer must organize production reasonably according to the order contract and technical conditions, ensuring that the produced products meet the usage requirements of the ordering unit (water supply company), thus guaranteeing consistency between the order and the supply. [b]10 Establish a Sound Inspection and Re-inspection System[/b] When a water supply company, after multiple investigations, surveys, and trials within a certain scope, finally selects one or more valve manufacturers and issues them permits to enter the local water supply market, it signifies the establishment of a supply and demand relationship between the water supply company and the valve manufacturers. Simultaneously, the valve manufacturers also bear joint responsibility for ensuring the safe and reliable water supply to the water supply company. On the one hand, valve manufacturers are required to consistently provide high-quality products according to the water supply company's requirements. On the other hand, to ensure quality, the water supply company is also required to establish a necessary and relatively complete periodic inspection and re-inspection system for designated manufacturers, generally every 2-5 years. The five key elements of personnel, machinery, materials, methods, and environment of designated manufacturers should be regularly inspected and evaluated. While inspecting manufacturers, the water supply company should also revise and supplement existing technical conditions as necessary based on the usage of valves within its own unit.