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Gate valvesFumagalli Componenti SpA is one of the world's largest manufacturers of gate valves and gate valve accessories. We produce superior resilient wedge gate valves made from long-lasting ductile iron. Follow the links on this page to discover more about the gate valves we produce. Gate valves (also known as knife valves or slide valves) are linear motion valves in which a flat closure element slides into the flow stream to provide shut-off. Gate valves and knife valves are designed to minimize pressure drop across the valve in the fully opened position and stop the flow of fluid completely. The direction of fluid flow does not change, and the diameter through which the process fluid passes is essentially equal to that of the pipe. Hence, they tend to have minimal pressure drop when opened fully. Gate valves and knife valves are advantageous in applications involving slurries, as their “gates” can cut right through the slurry. They are also used in applications that involve viscous liquids such as heavy oils, light grease, varnish, molasses, honey, cream and other non-flammable viscous liquids. They are available in large sizes to better handle thick flow. However, gate valves do have low-pressure limitations, and are not optimal in applications that require cleanliness or sanitary conditions. They are excellent for use anywhere a shutoff valve is needed. They can also be used where throttling capabilities are desired, although this is not generally recommended as erosion of the seat and disc occurs due to the vibrations of the disk in throttling applications. Gate valves are usually divided into two types: parallel and wedge-shaped. The parallel gate valve uses a flat disc gate between two parallel seats, upstream and downstream. Knife valves are of this type, but with a sharp edge on the bottom of the gate to shear entrained solids or separate slurries. In the double-disk parallel-seat type, the valve is closed by lowering the disks from the valve neck to a height equal to that of the valve seats. Once so positioned, an inclined plane mounted between the two disks coverts downward stem force into axial force and presses the parallel disks firmly against the valve seats sealing the two openings. These types of valve design can accommodate asymmetric or angularly misaligned valve seats. Wedge-shaped gate valves and knife valves use two inclined seats and a slightly mismatched inclined gate allowing for tight shut-off. Gate valves and knife valves are linear motion valves in which a flat closure element slides into the flow stream to provide shut-off. Learn more about Gate Valves on Fumagalli site. Gate Valves are the perfect compliment to our broad range of slurry handling products. All Valve knife gate valves are designed and engineered to a higher standard, to provide the best performance possible. Standard features such as precision-machines gates, heavy-duty topworks and cast-iron bodies up to 24" make the valves rugged and dependable. Other features such as replaceable wear seats, simplified packing replacement or solid stainless steel linings make the valves affordable and easy to maintain. Gate valves are utilized for residential and industrial applications. Most widely used as a component of fire hydrant kit assemblies, brass gate valves are also the choice for large agricultural irrigation systems and industrial systems where fluid flow control requires a high-performance, durable gate valve. GATE VALVES.— Gate valves are used when a straight-line flow of fluid and minimum restric- tion is desired. Gate valves are so named because the part that either stops or allows flow through the valve acts somewhat like the opening or closing of a gate and is called, appropriately, the gate. The gate is usually wedge shaped. When the valve is wide open, the gate is fully drawn up into the valve, leaving an opening for flow through the valve the same size as the pipe in which the valve is installed. Therefore, there is little pressure drop or flow restriction through the valve. Gate valves are not suitable for throttling purposes since the control of flow would be difficult due to valve design and since the flow of fluid slapping against a partially open gate can cause extensive damage to the valve. Except as specifically authorized, gate valves should not be used for throttling. Gate valves are classified as either RISING- STEM or NONRISING-STEM valves. On the nonrising-stem gate valve shown in figure 9-19, the stem is threaded on the lower end into the gate. As the handwheel on the stem is rotated, the gate travels up or down the stem on the threads, while the stem remains vertically stationary. This type of valve almost always has a pointer-type indicator Figure 9-19.—Cutaway view of a gate valve (nonrising-stem type). threaded onto the upper end of the stem to indicate valve position. The rising-stem gate valve, shown in figure 9-20, has the stem attached to the gate; the gate and stem rise and lower together as the valve is operated. Gate valves used in steam systems have flexible gates. The reason for using a flexible gate is to prevent binding of the gate within the valve when the valve is in the closed position. When steam lines are heated, they will expand, causing some distortion of valve bodies. If a solid gate fits snugly between the seat of a valve in a cold steam system, when the system is heated and pipes elongate, the seats will compress against the gate, wedging the gate between them and clamping the valve shut. This problem is overcome by use of a flexible gate (two circular plates attached to each other with a flexible hub in the middle). This design allows the gate to flex as the valve seat compresses it, thereby preventing clamping. BUTTERFLY VALVES.— The butterfly valve, one type of which is shown in figure 9-21, may be used in a variety of systems aboard ship. These valves can be used effectively in freshwater, saltwater, JP-5, F-76 (naval distillate), lube oil, and chill water systems aboard ship. The butterfly valve is light in weight, relatively small, relatively. Related links: fumagalli ball valves gate valves seamless pipes pipe fittings steel fittings carbon steel flanges carbon steel elbows cast steel valves cast iron valves butt welding fittings flange, curve, tubi e raccordi in acciaio valvole a saracinesca, a sfera, a disco e in ghisa |