译文：
减压阀是采用控制阀体内的启闭件的开度来调节介质的流量，将介质的压力降低，同时借助阀后压力的作用调节启闭件的开度，使阀后压力保持在一定范围内，并在阀体内或阀后喷入冷却水，将介质的温度降低，这种阀门称为减压减温阀。该阀的特点，是在进口压力不断变化的情况下，保持出口听压力和温度值在一定的范围内。 减压阀按结构形式可分为薄膜式、薄膜式减压阀、活塞式、杠杆式和波纹管式；按阀座数目可人为单座式和双座式；按阀瓣的位置不同可分为正作用式和反作用式。 (1) 调压范围：它是指减压阀输出压力P2的可调范围，在此范围内要求达到规定的精度。调压范围主要与调压弹簧的刚度有关。 (2) 压力特性：它是指流量g为定值时，因输入压力波动而引起输出压力波动的特性。输出压力波动越小，减压阀的特性越好。输出压力必须低于输入压力—定值才基本上不随输入压力变化而变化。 (3) 流量特性：它是指输入压力—定时，输出压力随输出流量g的变化而变化的持性。当流量g发生变化时，输出压力的变化越小越好。一般输出压力越低，它随输出流量的变化波动就越小。 减压阀的选用 根据使用要求选定减压阀的类型和调压精度，再根据所需{zd0}输出流量选择其通径。决定阀的气源压力时，应使其大于{zg}输出压力0．1MPa。减压阀一般安装在分水滤气器之后，油雾器或定值器之前，并注意不要将其进、出口接反；阀不用时应把旋钮放松，以免膜片经常受压变形而影响其性能。 减压阀的安装和维护应注意以下事项： 为了操作和维护方便，该阀一般直立安装在水平管道上。安装时应注意使管路中介质的流向与阀休上所示箭头的方向一致。为了防止阀后压力超压，应在离阀出口不少于4M处安装一个安全阀。 减压阀工作原理.减压阀使用方法 在物理化学实验中，经常要用到氧气、氮气、氢气、氩气等气体。这些气体一般都是贮存在专用的高压气体钢瓶中。使用时通过减压阀使气体压力降至实验所需范围，再经过其它控制阀门细调，使气体输入使用系统。最常用的减压阀为氧气减压阀，简称氧气表。 1.氧气减压阀的工作原理 氧气减压阀的高压腔与钢瓶连接，低压腔为气体出口，并通往使用系统。高压表的示值为钢瓶内贮存气体的压力。低压表的出口压力可由调节螺杆控制。 使用时先打开钢瓶总开关，然后顺时针转动低压表压力调节螺杆，使其压缩主弹簧并传动薄膜、弹簧垫块和顶杆而将活门打开。这样进口的高压气体由高压室经节流减压后进入低压室，并经出口通往工作系统。转动调节螺杆，改变活门开启的高度，从而调节高压气体的通过量并达到所需的压力值。 减压阀都装有安全阀。它是保护减压阀并使之安全使用的装置，也是减压阀出现故障的信号装置。如果由于活门垫、活门损坏或由于其它原因，导致出口压力自行上升并超过一定许可值时，安全阀会自动打开排气。 2.杠杆式减压阀的使用方法 (1)按使用要求的不同，杠杆式减压阀有许多规格。{zg}进口压力大多为，{zd1}进口压力不小于出口压力的2.5倍。出口压力规格较多，一般为，{zg}出口压力为。 (2)安装减压阀时应确定其连接规格是否与钢瓶和使用系统的接头相一致。减压阀与钢瓶采用半球面连接，靠旋紧螺母使二者xx吻合。因此，在使用时应保持两个半球面的光洁，以确保良好的气密效果。安装前可用高压气体吹除灰尘。必要时也可用聚四氟乙烯等材料作垫圈。 (3)氧气减压阀应严禁接触油脂，以免发生火警事故。 (4)停止工作时，应将减压阀中余气放净，然后拧松调节螺杆以免弹性元件长久受压变形。 (5)减压阀应避免撞击振动，不可与腐蚀性物质相接触。 3.其它气体减压阀 有些气体，例如氮气、空气、氩气等{yj}性气体，可以采用氧气减压阀。但还有一些气体，如氨等腐蚀性气体，则需要专用减压阀。市面上常见的有氮气、空气、氢气、氨、乙炔、丙烷、水蒸气等专用减压阀。 这些减压阀的使用方法及注意事项与氧气减压阀基本相同。但是，还应该指出：专用减压阀一般不用于其它气体。为了防止误用，有些专用减压阀与钢瓶之间采用特殊连接口。例如氢气和丙烷均采用左牙螺纹，也称反向螺纹，安装时应特别注意。

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原文：
Valve control valve is used to hoist the body parts to regulate the media, opening the flow of the media pressure has eased, at the same time with the role of back pressure regulating valve open and close the opening piece, so that back pressure valve to maintain a certain range , and at the valve body or valve sprayed into the cooling water lower the temperature to medium, such as decompression valve temperature valve reduction. The characteristics of the valve is in the inlet pressure to changing circumstances, to maintain the pressure and temperature values of export to listen to a certain range. Valve structure can be classified according to membrane, membrane-type pressure reducing valve, piston type, lever type and corrugated tube; by seat number could be man-made single-seat type and seat type; according to the location of valve flap can be divided into different positive role of the type and reaction type. (1) Voltage range: it refers to the valve output pressure P2 of the adjustable range, in this context requests reach the required accuracy. The major areas of surge voltage and the stiffness of the spring. (2) Pressure characteristics: it refers to the flow g as the fixed value, enter the pressure fluctuations due to pressure fluctuations caused by the output characteristics. Output pressure fluctuation smaller the better characteristics of valve. The output pressure must be less than the input pressure - it basically does not set the value varies with the input pressure. (3) Flow characteristics: it refers to the input pressure - from time to time, the output pressure with output flow g, and change the holding of. When the flow of g changes, the output pressure changes as small as possible. In general the lower the output pressure, which changes with fluctuations in the output flow rate smaller. Valve Selection Selected according to application requirements and the pressure regulator valve of the type of precision, and then according to the required maximum output flow rate to choose their path. Determine valve pressure gas source, should make it more than the maximum output pressure 0.1MPa. Valves usually installed in the Manifold air filtration devices, the oil mist or the device before the valuation, and be careful not to their import and export of anti-access; valves do not have the knob should be relaxed, so as not to affect the deformation of diaphragm compression often its performance. Valve installation and maintenance should note the following items: In order to facilitate the operation and maintenance, the valve installed in the level normally upright pipe. Installation of pipelines in the media should pay attention to the flow and the valve closing direction of the arrow shown on the line. In order to prevent over-pressure valve after the pressure should be at least 4M away from the exit valve to install a safety valve. Valve works. Valve use In physical chemistry experiments, often use the oxygen, nitrogen, hydrogen, argon and other gases. These gases are generally stored in a dedicated high-pressure gas cylinders in the. When used through the valve so that gas pressure down to test the required range, and then fine-tuning through the other control valves, so that gas entered the system. The most commonly used valve for the oxygen valve, referred to as oxygen table. 1. Oxygen valve works The high-pressure oxygen chamber and the cylinder valve connected to low-pressure chamber for gas exports and access to use the system. Table showing the value of high-pressure storage of gas cylinder pressure. Low table outlet pressure adjustment screw can be controlled. When you first open the cylinder using the master switch, and then the table clockwise rotating low pressure regulator screw to compress the main spring and the transmission film, spring pads, and push-rod and open the trap door. This high-pressure gas imports from the high-pressure chamber through the throttle after decompression into the low-pressure chamber, and the exit leading to the working system. Turn adjustment screw to change the valve opening height, thus regulating the passage of high-pressure gases to achieve the required amount of pressure value. Valves are equipped with safety valve. It is to protect the valve and make the safe use of the device, is also a valve failure signal device. If, living doormat, valve damage, or due to other reasons, resulting in increased outlet pressure, and exceeds a certain permission on their own value, the valve will automatically open the exhaust. 2. Lever-type valve to use (1) according to the different application requirements, lever-type valve has many specifications. The maximum inlet pressure the most part, the minimum inlet pressure of not less than 2.5 times the outlet pressure. Outlet pressure specification more, generally, the maximum outlet pressure of. (2) The installation of pressure reducing valve should be connected to determine whether the cylinder and the use of standard connector systems are consistent. Valve and the cylinder with hemispherical connections, tighten nut to rely on the two fit together well. Therefore, the use of the two hemispheres should be to maintain the smooth surface in order to ensure good gas-tight effect. Before installation can be high-pressure gas blowing addition to dust. When necessary, can also be used to make Teflon and other materials, gasket. (3) The oxygen valve should be forbidden contact with grease, so as to avoid fire accidents. (4) stop working when the valve should be placed in a net residual gas, and then loosen the adjustment screw so as to avoid long-term compressive deformation of elastic components. (5) The valve should be avoided shock vibration, can not be in contact with corrosive substances. 3. Other Gas Regulator Some gases, such as nitrogen, air, argon gas and other permanent gases, oxygen valve can be used. But there are a number of gases such as ammonia and other corrosive gases, you need special valve. Nitrogen available in the market are common, air, hydrogen, ammonia, acetylene, propane, water vapor and other special valves. The use of these valve methods and precautions with the oxygen valve basically the same. However, it should be noted: Private valve is generally not used for other gases. In order to prevent misuse, and some special valves and the cylinder using a special connection between the mouth. For example, hydrogen and propane are used thread left teeth, also known as reverse-threaded, the installation should be special attention.