A variety of valve definition classification and standards: First, the gate valve is one of the commonly used cut-off valve, mainly used to connect or cut off the medium in the pipeline, not suitable for regulating the medium flow. Gate valve for pressure, temperature and a large range of caliber, especially for medium and large diameter pipe. The main standard gate valve GB12232-89 "universal valve flange connection iron gate valve" GB12234-89 "universal valve flange and butt welding connection steel gate valve" GB8464-87 "internal thread connection gate valve, globe valve, ball valve, check valve General technical conditions "GB8465.1-87" threaded connection gate valve, globe valve, ball valve, check valve basic size iron gate valve "JB / T53162-91" gate valve product quality classification "JB / T5298-91" pipeline steel Flat gate valve "JB / Z243-85" gate valve static pressure life test rules "JB / TQ648-88" iron plate type flat gate valve "JB / T53200-94" iron plate type flat gate valve product quality classification "JB / T53242-94 "Steel plate gate valve product quality classification" Second, the cut-off valve, throttle valve Globe valve is a commonly used cut-off valve, mainly used to connect or cut off the medium in the pipeline, generally not used to regulate the flow . Globe valve pressure, temperature range, but generally used for medium and small caliber pipe. The main standards of the globe valve GB12233-89 "universal valve iron stop valve and lifting check valve" GB12235-89 "universal valve flange connection steel stop valve and lift check valve" JB / T53174-94 "globe valve Product quality classification "JB / T53165-92" high pressure balance valve product quality classification "GB / T587-93" marine flange bronze globe valve "GB / T590-93" marine flange cast iron globe valve "GB8464-87" Internal thread connection gate valve, globe valve, ball valve, check valve General technical conditions "GB8465.2-87" internal thread connection gate valve, globe valve, ball valve, check valve basic size iron globe valve "Third, the throttle throttle Valve is to change the flow cross-section to control the pressure and flow of fluid, which belongs to the control valve, but because of its structural constraints, there is no control valve adjustment characteristics, it can not be used instead of the control valve. Cut-off type throttle valve in addition to the structure and related parts, are the same with the cut-off valve. Most of the throttle opening and closing parts for the streamlined streamline. Fourth, butterfly valve Butterfly valve is used with the rotation of the circular disc for the opening and closing pieces, in order to achieve opening and closing of the valve. Butterfly valve is mainly used to cut off valve can also be designed to adjust or cut off and adjust the function. At present, the use of butterfly valves in low-pressure large and medium-diameter pipes is more and more. Butterfly valve main standard GB12238-89 "Universal valve flange and butterfly valve connected to the butterfly" JB / T53171-94 "butterfly valve product quality classification" JB / Z248-85 "butterfly valve static pressure life test procedures" Fifth, the check valve check A valve is a valve that automatically stops fluid from flowing back. The check valve flap opens under fluid pressure and fluid flows from the inlet side to the outlet side. When the pressure on the inlet side is lower than on the outlet side, the valve flap closes automatically under the effect of fluid pressure difference and gravity itself to prevent fluid backflow. GB12233-89 "universal valve iron stop valve and lifting check valve" GB12235-89 "universal valve flange connection steel stop valve and lift check valve" GB12236-89 "universal valve steel swing check Valves "GB / T13932-92" Universal Valve Swing Check Valve "GB / T589-93" Marine Flange Bronze Check Valve "GB / T592-93" Marine Flange Cast Iron Check Valve "GB8464-87 "Internal thread connection gate valve, globe valve, ball valve, check valve General technical conditions" GB8465.4-87 "Internal thread connection gate valve, globe valve, ball valve, check valve Basic dimensions Iron check valve" JB / T53036-92 " Check valve product quality grading "VI Ball valve Ball valve is used with a circular hole for the opening and closing pieces, the ball with the stem rotation, in order to achieve the valve opening and closing action. The main standard ball valve GB12237-89 "universal valve flange and butt welded steel ball valve" GB / T15185-94 "iron and brass ball valve" GB8464-87 "threaded connection gate valve, globe valve, ball valve, check valve General technical conditions "GB8465.3-87" internal thread connection gate valve, globe valve, ball valve, check valve basic size iron ball valve "JB / T53167-94" ball valve product quality classification "JB / Z246-85" ball valve static pressure Life Test Regulations "7. Diaphragm valve Diaphragm valve is a special form of the cut-off valve. The opening and closing piece is a diaphragm made of soft material, which separates the valve body cavity from the valve cover cavity. 8, Plug Valve Plug valve is a hole with the plug body as the opening and closing pieces, plug body with the stem rotation, in order to achieve opening and closing action of the valve. Stopcock plug bodies are mostly cones, but also cylindrical, plug the valve structure is simple, quick opening and closing, fluid resistance. Plug valve is usually used for pressure is not high, small caliber occasions. Plug valves are used to cut off the media flow, but also for media distribution, three-way stopcock and four-way stopcocks are used to change the direction of media flow or media distribution. Nine, the plunger valve ten, safety valve safety valve used in boilers, pressure vessels and other pressure equipment as an overpressure protection device. When the medium pressure in the equipment to be protected abnormally increased to meet the specified value, the valve automatically opens, and then the full amount of emissions, to prevent the pressure continues to rise, when the pressure drops to another specified value, automatically shut down. The main standards of safety valve GB12241-89 "safety valve general requirements" GB12242-89 "safety valve performance test method" GB12243-89 "spring direct load relief valve" ZBJ98013-89 "technical conditions of power station safety valve" JB / T53170-94 "Direct spring loaded valve safety valve product quality grading" Eleven, pressure reducing valve Pressure reducing valve is a kind of regulating valve, it is throttling the opening and closing parts, the inlet pressure will be reduced to a certain outlet pressure, And in the import pressure and flow changes, the use of the energy of the media itself to maintain the outlet pressure is basically the same valve. Twelve, trap Trap is used in steam pipe network and equipment, can automatically drain the condensate, air and other non-condensable gas, and water vapor leak valve 13, the sewage valve fourteen, the valve In the water, steam pipe network as a regulation of traffic, self-locking type can always maintain a balanced network. Fifteen other valves Pipe clamp emergency cut-off valve and safety accessories solenoid valve vacuum valve Cylinder valve Multi-purpose valve special valve and special valve Sixteenth, the valve drive manual electric pneumatic Keywords: valve