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an công nghiệp là gì? Van công nghiệp là một thiết bị cơ khí sử dụng trong hệ thống ống dẫn trong ngành công nghiệp, dùng để đóng mở, điều chỉnh và kiểm soát dòng chảy đi qua bên trong đường ống. Van công nghiệp là một thiết bị được sử dụng rộng rãi trong nhiều ngành nghề thông dụng mà bất cứ ai trong chúng ta cũng đã từng biết đến như: sản xuất thực phẩm, sản xuất nước giải khát, sản xuất thức ăn chăn nuôi gia súc thủy sản, ngành may mặc dệt nhuộm, sản xuất hóa chất , ngành cấp và xử lý nước, vv…. Các loại van công nghiệp thông dụng trên thị trường: Van công nghiệp rất nhiều mẫu mã và nhiều chủng loại khác biệt nhau. Tùy vào môi chất sử dụng, vị trí lắp đặt nhu cầu sử dụng van để có thể chọn loại van thích hợp nhằm điều khiển môi chất bên trong ống. Trên thị trường hiện tại, gồm có những loại van được sử dụng phổ biến nhất như: Van cầu Bellow seals globe valves Van bi Ball valves Van một chiều Check valves Van cửa, van cổng Gate valves Van bướm Butterfly valves Van dao Knife gate valves Van an toàn Safety valves Van giảm áp Reducing valves Van điều khiển Control valves Van xiên Angle seat valves Van điện từ Solenoid valves
74 Valves Functions Block flow Throttle flow Prevent flow reversal Safety Valve Action Explanation ON / OFF Starting Flow / Stopping Flow Regulating Varying the rate of Flow Checking Permitting Flow in one direction only Switching Switching Flow Along different Router Discharging Discharging fluid from a system 75 Valves General procedure for valve selection Identify design information including pressure and temperature, valve function, material, etc Identify potentially appropriate valve types and components based on application and function (i.e., block, throttle, or reverse flow prevention) Determine valve application requirements (i.e., design or service limitations) Finalize valve selection Check factors to consider if two or more valves are suitable Provide full technical description specifying type, material, flange rating, etc 76 Valves End Connections Function Of Valve 77 Valves 78 Valves 79 Valves Gate valves: Gate valves are the most common type of valve sials Gate valve consists of a body that contains a gate that interrupts flow Normally used in a fully open or fully closed position Gate valves may be used in systems where flow direction varies and can be reversed as this valve type is “bi-directional Gate valves larger than in (51 mm) usually have port openings that are approximately the same size as the valve end openings which is called a full-ported valve Reduced port gate valves have port openings that are smaller than the end openings 80 Valves Gate valves 81 Valves Gate valves 82 Valves Gate valves: (disadvantages) The full stem travel requires many turns of a handwheel and many more turns when fitted with gearing Due to the long stroke and the outside appurtenances necessary to accommodate this stroke, a longer space envelope (over-all length) is required Body seat surfaces for gate valves are more difficult to machine or refinish Solid wedge gate valves in systems where severe temperature changes occur are also subject to excessive seat leakage due to changes in angular relationship between the wedge and the seat faces due to pipe loads exerted on the valve ends Metal-seated gate valves should not be used for air or gas service because they not have the bubble-tight closure necessary for these services 83 Valves Ball Valves 96 Valves Diaphragm Valves 97 Valves Diaphragm Valves A diaphragm valve is a packless valve that contains a diaphragm made of a flexible material that functions as both a closure and a seal Diaphragm valves not used extensively in the petrochemical industry but they have application in corrosive services below 121 °C where a leak tight valve 98 Valves Butterfly Valves 99 Valves Butterfly Valves The butterfly valve (also called a trunnion valve) is a quarter turn valve that rotates a disc in the flow stream A butterfly valve is from a family of valves called quarter-turn valves In operation, the valve is fully open or closed when the disc is rotated a quarter turn Butterfly valves are generally used as stop valves or regulating flow Large butterfly valves are generally mechanically operated 100 Valves Check Valves 101 Valves Check Valves The check valve operates automatically to pass flow in one direction, and prevent any reversal of flow Check valves work automatically and most are not controlled by a person or any external control Does not completely shut off reverse flow 102 Valves Check Valves 103 Valves Check Valves 104 Valves Check Valves 105 Valves Check Valves 106 Valves Slide Valves 107 Valves Slide Valves The slide valve is a rectilinear valve used to control the admission of steam into, and emission of exhaust from, the cylinder of a steam engine One popular application of this type of valve is controlling fluidized catalyst flow in fluid catalytic cracking (FCC) units slide valve consists of a flat plate that slides against a seat Slide valve uses a fixed orifice and one or two solid slides that move in guides, creating a variable orifice that make the valve suitable for throttling or blocking 108 Valves Relief and Safety Valves Relief and safety valves prevent equipment damage by relieving accidental overpressurization of fluid systems The main difference between a relief valve and a safety valve is the extent of opening at the set point pressure A relief valve gradually opens as the inlet pressure increases above the set point A safety valve rapidly pops fully open as soon as the pressure setting is reached A safety valve will stay fully open until the pressure drops below a reset pressure The reset pressure is lower than the actuating pressure set point Relief valves are typically used for incompressible fluids such as water or oil Safety valves are typically used for compressible fluids such as steam or other gases 109 Valves Relief and Safety Valves Relief valve Safety valve 110 ... ball valve is used frequently for diverting flows to several directions using a single valve 93 Valves Ball Valves 94 Valves Ball Valves 95 Valves Ball Valves 96 Valves Diaphragm Valves 97 Valves... Globe Valves Four Common Disc Designs Plug Composition Needle Ball 88 Valves Globe Valves 89 Valves Plug Valves 90 Valves Plug Valves Plug valves usually used to close off flow A plug valve. .. material, flange rating, etc 76 Valves End Connections Function Of Valve 77 Valves 78 Valves 79 Valves Gate valves: Gate valves are the most common type of valve sials Gate valve consists of a body