Analysis of the advantages and disadvantages of various valve
Wide range of valves, each have their own application environments, and the advantages and disadvantages. Following analysis of some common advantages and disadvantages of valves.(1) valve is not used as regulating the flow. It can be widely applied for low temperature pressure can also be used in high temperature and high pressure, and according to the valves of different material. Gate valves are generally not used for transporting slurry pipeline of such medium.Advantages: smaller fluid resistance; less torque required to open, close and can be used in the media to the two way ring road network management, which means that unlimited flow of media; when fully opened, sealed surface erosion than globe valves of medium small; the form structure is relatively simple, good manufacturing process structure length is shorter.Disadvantages: overall dimensions and large opening height, the space needed to install larger; in the process of opening and closing, sealing surface friction, wear large, even at high temperatures is easy to cause abrasions; valve has two sealing surfaces, add difficulties to the machining, grinding and repair; opening and closing time.
(2) the butterfly valve: Yes disc discs for reciprocating rotating 90 degrees to open and close a valve and adjust the fluid channel.Advantages: simple, open and close rapidly, small flow resistance, used in large diameter valves; can be used for medium with suspended solid particles, according to the sealing surface of the strength can also be used for powder and granular media. Bidirectional opening and closing and adjustment of suitable for the ventilation and dust removal pipeline, widely used in metallurgy, light industry, electric power, petroleum chemical industry, such as gas pipelines and waterways.Disadvantage: limitations due to the structure of the butterfly valve and sealing materials to be used for high temperature, high pressure in the pipeline system; poor relative to the ball valve, globe valve sealing performance, used for sealing requirements are not very high places; flow adjustment range is small.
(3) ball valves: its discs is a sphere, a sphere around the stem to the axis of rotation 90 ° to achieve open and close aim, is evolved from the stopcock. Ball valves on the pipes are mainly used for cutting, assign and change the direction of flow, designed v-shape open ball valve has a good flow control function.Advantages: minimum flow resistance (actually 0), due to not be stuck at work (no lubricant); in a wide range of pressure and temperature, can be completely sealed for fast opening and closing, opening and closing time of certain structures is only 0.05~0.1s, to ensure that the automation system can be used for test-bed. Quick on-off valve, the operation of shock. Spherical close pieces can in border location Shang automatically positioning; in full and full closed Shi, sphere and valve seat of sealed surface and media isolation, so high-speed through valve of media not caused sealed surface of erosion; structure compact, and weight light, can think it is for low temperature media system of most reasonable of valve structure; valve body symmetric, especially welding valve body structure, can is good to bear from pipeline of stress; close pieces can bear close Shi of high pressure poor. ⑾ fully welded ball valve valve body can be buried in the ground, so that in case the valve is not affected by erosion, is the most ideal valve oil and natural gas pipelines.Disadvantage: because the ball valve the main valve seat seal materials are Teflon, it is inert to almost all chemicals, and has a low coefficient of friction, stable performance, easy to aging, wide temperature application range and characteristics of good performance to seal a comprehensive. However, the physical properties of PTFE, including the higher coefficient of expansion, sensitivity to cold and poor thermal conductivity, requires seating must be designed around these properties; its performance relative to the valve is less, especially pneumatic valves (or electric valve).(4) stop valves: refers to the closed (valve) moves along the seat centre line valve. According to this mobile form of disc, seat vents are and are proportional to the valve stroke. Due to open or close the valve stem travel relatively short, due to the openings of the valve seat travel proportional relationship with the disc, very suitable for regulation of the flow. Therefore, this type of valve is moved to cooperation to cut off or adjusting the throttle.
Advantages: in opening and closing process in the, due to valve flap and valve body sealed surface between of mill wipe force than gate small, thus wear; opened height General only for valve seat channel of 1/4, so than gate small have more; usually in valve body and valve flap Shang only a sealed surface, thus manufacturing process sex compared good, easy maintenance; due to its filler General for asbestos and graphite of mixture, so resistance temperature grade high. Steam valve stop valve.Disadvantages: due to changes in flow direction through the valve, globe valves minimum flow resistance is higher than most other types of valves because of the long trip, open speed ball valve slowly.Source: http://www.imgvalves.com/de