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Commonly used valves and heating engineering projects
1 valve classification In the heating system, there are many kinds of valves used. Such as gate valve, globe valve, ball valve, butterfly valve, check valve, safety valve, control valve, balance valve, self-balancing valve and so on. Introduced below one by one. 1.1 Gate valve also called gate valve, gate valve, is a widely used type of valve. How it works: Gate sealing surface and seat sealing surface height smooth, flat, consistent, processed into a very fit, tight seal pair. Gate through the valve stem on the mention, under pressure, the media formed on and off. It plays a shut-off role in the pipeline. Advantages: small fluid resistance; fully open sealing surface from erosion; can be used in the media two-way flow, there is no directionality; durable; not only suitable for small valves, but also can make the valve bigger. Disadvantages: height; opening and closing a long time; bulky; difficult to repair; if it is large-caliber gate valve, manual operation more laborious. Gate valve according to the different stem of the rod and dark rod; according to the structure of different sub-gate ramps and wedge; there is a single gate, double gate points. Heating projects, the commonly used is the rod wedge single gate valve (Z41H-16C) and the dark rod wedge gate valve (Z45T-10), the former installed in the thermal station on the primary side, the latter installed in the thermal station Secondary side. It generally serves two functions: acting as a master device for switching purposes; serving as a secondary device for overhauling the primary device. Gate valve installation, do not make the hand wheel at the level of the following (flip), otherwise it will leave the medium in the valve cover long-term, easy to corrode the valve stem. In the heating project, the valve has been the main force in the valve. Now with the widespread adoption of butterfly valves, butterfly valves have been replaced by butterfly valves. 1.2 Globe valve is also a widely used type of valve. The general caliber is below 100 mm. It works similar to the gate valve, only the closure (valve) moves along the centerline of the valve seat. It plays a shut-off role in the pipeline, but also a rough adjustment of flow. Advantages: easy to manufacture, easy maintenance, durable. Disadvantages: only allow one-way flow of media, installation direction. Large flow resistance, poor sealing. Divided by the structure of different straight-through, right angle, DC, balanced. The project generally use the flange straight (J41H) and the female straight through (J11H). Globe valve directional, can not be reversed. It is not appropriate. In our production, life, used to pass the past, small-diameter globe valve, now gradually replaced by the ball valve. 1.3 Ball Valve Compared to the gate valve, globe valve, ball valve is a new type, gradually widely used valves. Its working principle is: The valve core is a ball with a through cavity, which is rotated 90 ° by the valve stem to make the valve clear or blocked. It plays a shut-off role in the pipeline. Advantages: In addition to the advantages of gate valves and globe valves, there are advantages of small size, good sealing (zero leakage) and easy operation. Currently in petrochemical, power, nuclear energy, aviation, aerospace and other departments widely used. Disadvantages: Maintenance difficulties. Ball valve in two forms: floating ball and fixed ball. In the heating project, a number of key locations, such as important branches, heating station population, DN250 below, often using imported ball valves. Ball valve with its domestic structure is different: the ball valve body is generally two-block, three-block, flange connection; and the valve body is imported ball valve integration, welding connections, fewer points of failure. Its origin is northern Europe such as Finland, Denmark and other heating technology more developed countries. Such as Finland's NAVAL, VEXVE, Denmark's DAFOSS and so on. Due to its excellent sealing, the reliability of the operation, has long been popular with users. Ball valve non-directional, can be installed at any angle. When the welding ball valve is installed horizontally, the valve must be opened to avoid sparking and the surface of the ball during welding. When welding on the vertical pipe, the valve must be opened. If the welding interface is under pressure, the valve must be closed to prevent the internal Burned by high fever. 1.4 butterfly valve in the heating system, is currently the most widely used, a type of valve is also the most. How it works: Disc is a disc, rotating through the valve stem, the valve disc in the valve seat for 90 ℃ rotation, the valve switch. It plays a shut-off role in the pipeline. Can also adjust the flow. Advantages: simple structure, compact size, easy operation, good sealing. Disadvantages: fully open, the valve plate (ring) by the media erosion. In the heating project, the butterfly valve used three eccentric metal sealing butterfly valve, rubber soft sealing butterfly valve.