Valves are widely used in heating and air conditioning water systems to control water pressure, flow and flow. Heating air-conditioning water system valve type and working principle: Heating and air conditioning water system valves commonly used in valve body structure and function can be divided into gate valve, butterfly valve, globe valve, ball valve, plug valve, check valve, pressure reducing valve , Safety valve, steam trap, balance valve and the like. In accordance with the driving method is divided into manual, electric, hydraulic, pneumatic and other four ways. In accordance with the nominal pressure points high pressure, medium pressure, low pressure three categories. The working principle and characteristics of the valves commonly used in heating and air conditioning water system are as follows: The gate valve refers to a valve that moves in the vertical direction along the axis of the medium passage of the closing member. The advantage is that the flow resistance coefficient is small, the torque required for opening and closing is small, and the medium flow direction is not limited. The disadvantage is the size of the structure, opening and closing a long time, sealing surface easily damaged, complex structure. The gate valve is divided into different types, the most common form is parallel and wedge gate valve, according to the structure of the stem can also be divided into Ming rod gate valve. Gate valve structure can be divided into the following four types: Gate valve (1) Parallel gate valve: refers to the two sealing surfaces parallel to each other gate valve. For low pressure, medium and small diameter (DN50-400mm) of the pipeline. (2) wedge gate valve: refers to the two sealing surface into a wedge-shaped gate valve. Divided into two sets of board, a single board and elastic board. (3) Ming rod gate valve: As can be more intuitive display of the degree of opening and closing, so many years of small and medium diameter is widely used, usually less than or equal to 80mm DN selected Ming rod valve. (4) dark bar gate valve: the stem nut in the valve body and the media in direct contact. For large-diameter valves and installation space is limited by the pipeline, such as underground pipelines. Butterfly valve its name comes from the wings of the butterfly structure. In the pipeline it is mainly used for cutting and throttling, when the butterfly valve is used to cut off, the use of flexible seal, the material selected rubber, plastic, etc., when used for throttling, the use of metal seal. Guilong butterfly valve has the advantages of small size, light weight, simple structure, quick opening and closing, regulation and sealing performance is good, the fluid resistance and torque smaller. According to the structure of the butterfly valve can be divided into lever (double rocker), the center of symmetry refers to the body closed valve (valve) along the valve seat center line of the valve. It is generally only used in the pipeline cut off, but not for throttling, usually nominal diameter are limited to DN250mm below. The disadvantage is the pressure loss. Many kinds of globe valves, according to the structure is generally divided into straight-through, and DC-type. Angle valve in the refrigeration system is more used, the inlet channel was 90 degrees at right angles, will produce pressure drop, the biggest advantage is installed in the corner of the piping system, both 90-degree bend, but also easy to operate. Ball valve ball valve is evolved from the plug valve, which is mainly used in the pipeline to cut off, distribute and change the media flow. It is characterized by the smallest fluid resistance, the same coefficient of resistance with the same length of the pipe, opening and closing fast, reliable sealing, compact structure, easy operation and maintenance, which are widely used in many occasions. Ball valve according to the structure of the ball can be divided into the following three types: (1) floating ball valve: its simple structure, good sealing performance, due to the ball bearing the working medium load all transmitted to the outlet valve seat ring, so this Structure is only suitable for medium and low voltage occasions, the disadvantage is the assembly difficulties, high precision requirements, while operating torque is also large. (2) fixed ball valve: ball valve ball fixed by the two connected with the ball fixed shaft support, under the media pressure, the ball will not produce displacement. It is suitable for high pressure and large diameter pipe. (3) flexible ball valve: suitable for high temperature, high pressure medium. There is an elastic groove on the ball body, this structure can reduce the friction between the two sealing surfaces when opening and closing, and also reduce the operating torque. An important feature of the stopcock stopcock is its ease of adaptation to multichannel structures so that one valve can take two, three or even four different runners. Many types of cocks, generally can be divided into: (1) tight plug valve: generally used in PN less than or equal to 0.6MPa occasions. (2) packing plug valve: a large number of nominal pressure PN> 1.0MPa occasions. (3) self-sealing plug valve: mainly rely on the pressure of the medium itself to achieve, and more for the air medium. Spring below the self-sealing structure can play the role of pre-tensioning and compression. In addition there are three links, four-way plug valves, and more for distribution, commutation and so on. Check valve, also known as counter-flow valve, check valve, back pressure valve and check valve. Is a valve used to prevent backflow of media in pipes and equipment that automatically opens and closes by the force generated by the flow of the medium itself in the pipe. Shanghai GuiLuan spin-Kai-valve valve around the valve seat outside the rotation of the pin, sub-single and multi-valve, the former generally used for nominal diameter DN50-500mm, which is generally used for nominal diameter DN greater than or equal to 600mm. There are empty row check valve is used for boiler feed pump outlet to prevent media backflow and emptying from the role of the new slow closing check valve, eliminating the role of water hammer; diaphragm check valve to prevent water hammer performance is good; Ball check valve, is to prevent the reverse flow of the ideal product. Reducing valve is through throttling and adjustment of the valve, the media pressure is reduced, and through the valve after the direct effect of media pressure, the pressure after the valve automatically meet the predetermined requirements. Pressure P2 after the valve is usually less than the pressure before the valve P1 0.5 times, that is P2> 0.5P1. Pressure relief valve according to the structure is divided into piston, film, bellows, spring film type, lever spring type. Safety valve It is used as a safety device on equipment, fittings and piping to prevent the pressure of the medium from exceeding the specified value. The main structure of the safety valve lever, spring and pilot (pulse) three. The advantage is small size, light weight. Sensitivity, the installation position is not limited; the disadvantage is that the force acting on the stem changes with the spring deformation. Spring-loaded safety valve is divided into micro-and full-Kai, with a wrench and without a wrench, closed and open different types. Traps Traps for steam heating equipment and piping to automatically remove condensate, air and other non-condensable gases, and to prevent the loss of steam, which play a role in blocking the drainage of water. Selection, the first according to the maximum displacement of condensate and import and export of pressure differential selection, but also be amended, the correction factor of 1.5-4; followed by a reasonable installation. Steam trap by opening and closing the form can be divided into the following categories: (1) mechanical steam traps: from the condensate level change public drive opening and closing pieces. (2) Thermostatic steam traps: Driven by changes in condensate temperature. (3) Thermodynamic steam traps: change from the dynamic properties of condensate into the public drive valve. Counterbalance valve Counterbalance valve is used in hydraulic networks to measure and adjust to the design flow, and has the necessary accuracy of the valve. Guilong balance valve is a special function of the valve, it has good flow characteristics, the valve opening instructions,
