Rotary valve features and types: 1, rotary valve features: The valve is usually divided into straight-line program and rotary two categories. Straight-stroke valves allow or shut off the flow of fluid through a rectilinear moving part such as a ram. Straight travel valves are globe valves, gate valves, diaphragm valves and so on. Rotary valves allow or shut off the flow of fluid through a rotating part. Rotating parts can rotate 90 degrees rotary valve called 1/4 rotary valve. Sometimes 1/4 rotary valve classification can be expanded to less than 270 degrees of rotation of the rotary valve. As can be seen by definition, a rotary valve is a rotary valve that changes the valve from opening to closing by rotating a rotating member such as a rotating shutter by 90 degrees. Rotary valve generally has the following characteristics. (1) Adjustable Range The adjustable range is the most critical in the process industry. The rotary valve has an adjustable range of approximately 150: 1 (VALTEK's ball valves can be adjusted up to 300: 1, butterfly valves and cam-bend valves The adjustable range is 100: 1). Corresponding to the cut-off valve adjustable range of 30: 1, which means that the rotary valve can provide 5 times the width of the adjustable range. For example, at a maximum flow rate of 1000 l / min, the shut-off valve can effectively reduce the flow rate to 30 l / min and the rotary valve can adjust the flow rate to less than 10 l / min. The more accurate the critical valve control flow, The better the repeatability, the direct reduction of unqualified products in the process industry. Eccentric rotary valve features two to enhance its adjustable range, the first is its orifice design, the eccentric is an effective 1/4 of the park, eccentric spool is V-type, while the traditional spool is In the parked shape, when the eccentric rotary valve is off, its small V shape allows for very precise control at low flow rates, and for large flow rates it opens the valve almost to the same diameter as the pipe. The second feature is the implementation of the trip machine rotary valve actuator with a certain stroke of the membrane and cylinder two. 1 "shut-off valve stroke is about 3/4" ~ 7/8 "and rotary valve stroke more than 2". For any other size valve. The greater the stroke of the input, the better control is at the working end. Highly variable ratio control valves provide the exact formulation required by the recipe regardless of the flow rate of the individual flowpaths. Conventional linear or regulating valves are no longer suitable for such tasks. Rotary valves increase device performance while reducing the need for control valves. The cost of plant life cycle. A wide range of adjustable rotary valves allow users to improve their tightness and cut-off standards, thereby increasing cost / benefit metrics. The metal seat plus the village made of special material can prolong the service life of the valve and improve the performance of the valve. The simple design of the rotating structure can minimize the maintenance workload. Reduce the owners of production costs. (2) Strictly cut off the shaft of the straight stroke valve stem is the stem out of the valve body, each cycle with a product, for straight stroke design to avoid leakage is difficult, it can be unwanted products into the production process system, And can produce large unacceptable factory volatile external leakage. Rotary valve rotary design is essentially free of this problem, because the valve uses a low hysteresis, high thrust cylinder actuator can provide more precise than the other forms of implementing agencies more stability, has the ability to provide long-term tight Cut off the metal seat. (3) Circulation capacity Large size Small straight stroke valve flow capacity is the installation of the valve flow capacity of the pipeline to improve the flow capacity of the method is to improve the size of the straight-stroke valve, usually larger than the pipeline may be. Rotary valves have a capacity of about 2 to 3 times that of a straight-stroke valve of the same size. Rotary valves can be used to increase the amount of blending without changing the size of the feed line, which can greatly reduce costs. For this reason, some rotary valves have been It is designed as a flange-to-flange connection instead of a stop valve and is equipped with connecting bolts which are even cheaper than the globe valves they replace. (4) Anti-cavitation Throttling in the process industry can cause significant cavitation which can damage the pipe and create an unacceptable level of noise while disturbing the gauging system causing unclear or unreliable readings, The rotary valve has a robust design that greatly reduces valve failure due to water hammer, while its spool absorbs part of the excess energy, significantly reducing cavitation and related problems. (5) No external leakage Standard rotary valves are 100 times more leak-proof than standard stop-valve designs and the movement of the stem of the shut-off valve pulls the dust in and carries sand into the valve thereby damaging the graphite packing. In the rotary valve stem does not make any access to the movement, but for the rotation movement, so as not to damage the packing, to avoid external leakage. (6) Maintenance costs and spare parts Metal seat rotary valve spare parts than the cut-off valve is much less maintenance is usually relatively easy. 2, the type of rotary valve: 2.1, in accordance with the type of classification Rotary valve classification in accordance with the type has three types: butterfly valve, ball valve and plunger valve. 1), butterfly valve: through the baffle or blade to the shaft as the center rotation angle to control the flow direction. The baffle or blade looks a bit like a butterfly. Butterfly valve can cut off or adjust the role of slurry or with suspended solids for the fluid. 2) Ball Valve: Its spool is a spherical body with a circular hole, allowing the fluid to flow when the valve is in the open position, and cutting the spherical body 90 degrees to cut off the flow. Ball valve can cut off and adjust the role of its pressure drop is small, suitable for viscous and corrosive fluids, slurry cryogenic fluid. Ball valve can also be used for high temperature, high pressure fluid. 3), the plunger valve: its spool is a conical or cylindrical plunger with a hole in the middle, when the plunger hole and the flow direction of the fluid can be passed, when the plunger rotated in any direction 90 degrees flow path Was cut off. Plunger valves are commonly used for on / off control. 2.2, according to the operation classification Rotary valve in accordance with the operation mode has the following types: manual valve, automatic valve and control valve. 1), manual rotary valve: manual operation, by manual actuators such as hand rods, gears, handwheels, etc. to switch operations, including a 90-degree rotation of the components. The actuator opens and closes the valve by operating the valve stem and flow control element. 2), automatic rotary valve: including an automatic actuator, the use of external energy to automatically control or remote control valve switch. Automatic valves should generally be used in the following situations: Large valves (eg valves> 8 "), valves that are difficult to operate manually, in toxic or other harsh environments Manual operation of the valve is not possible. To handle an emergency the valve must Quick shut-off valves, valves for all flow paths in batches, etc. The types of automatic actuators include hydraulic, pneumatic and electric etc. Most automatic rotary valves are operated by electric and pneumatic actuators 3) : Can operate at a specific opening, this type of valve includes an electric actuator can produce a corresponding corner according to the size of the electrical signal. Butterfly valve is commonly used in low-pressure large-diameter, less stringent requirements on the leakage control. Rotary control valve is a Control valve, control valve also includes some straight-stroke valve such as globe valve, gate valve, diaphragm valve.Automatic rotation of the cut-off valve is not a control valve, because it can only be limited to open and closed position.