疏水阀在蒸汽加热系统中起到阻汽排水作用，选择合适的疏水阀，可使蒸汽加热设备达到最高工作效率。要想达到最理想的效果，就要对各种类型疏水阀的工作性能、特点进行全面的了解。

　　The steam trap plays a role in blocking steam and draining water in the steam heating system. Choosing a suitable steam trap can achieve the highest working efficiency of the steam heating equipment. To achieve the most ideal effect, it is necessary to have a comprehensive understanding of the working performance and characteristics of various types of drain valves.

　　疏水阀的品种很多，各有不同的性能。选用疏水阀时，首先应选其特性能满足蒸汽加热设备的最佳运行，然后才考虑其他客观条件，这样选择你所需要的疏水阀才是正确和有效的。

　　There are many types of drain valves, each with different performance. When selecting a steam trap, the first thing to consider is its characteristics that can meet the optimal operation of steam heating equipment, and then other objective conditions should be taken into account. Only in this way can you choose the steam trap you need correctly and effectively.

　　疏水阀要能“识别”蒸汽和凝结水，才能起到阻汽排水作用。“识别” 蒸汽和凝结水基于三个原理：密度差、温度差和相变。于是就根据三个原理制造出三种类型的疏水阀，分类为机械型、热静力型、热动力型。

　　A drain valve must be able to "identify" steam and condensate in order to effectively block steam and drain water. The identification of steam and condensate is based on three principles: density difference, temperature difference, and phase transition. So three types of steam traps were manufactured based on three principles, classified as mechanical, thermo static, and thermo dynamic types.

　　一.机械型疏水阀

　　One Mechanical drain valve

　　机械型也称浮子型，是利用凝结水与蒸汽的密度差，通过凝结水液位变化，使浮子升降带动阀瓣开启或关闭，达到阻汽排水目的。机械型疏水阀的过冷度小，不受工作压力和温度变化的影响，有水即排，加热设备里不存水，能使加热设备达到最佳换热效率。最大背压率为80%，工作质量高，是生产工艺加热设备最理想的疏水阀。

　　Mechanical type, also known as float type, utilizes the density difference between condensed water and steam to adjust the liquid level of condensed water, causing the float to rise and fall and drive the valve disc to open or close, achieving the purpose of blocking steam and draining water. Mechanical drain valves have low undercooling and are not affected by changes in working pressure and temperature. Water is discharged as soon as it is available, and there is no water stored in the heating equipment, which can achieve optimal heat transfer efficiency. The maximum back pressure rate is 80%, with high working quality, making it the most ideal drain valve for heating equipment in production processes.

　　机械型疏水阀有自由浮球式、自由半浮球式、杠杆浮球式、倒吊桶式等。

　　Mechanical drain valves include free floating ball type, free semi floating ball type, lever floating ball type, inverted bucket type, etc.

　　1.自由浮球式疏水阀：

　　1. Free floating ball drain valve:

　　自由浮球式疏水阀的结构简单，内部只有一个活动部件精细研磨的不锈钢空心浮球，既是浮子又是启闭件，无易损零件，使用寿命很长，“银球”牌疏水阀内部带有Y系列自动排空气装置，非常灵敏，能自动排空气，工作质量高。

　　The structure of the free floating ball type drain valve is simple, with only a finely ground stainless steel hollow floating ball as a moving part inside. It is both a float and an opening and closing part, with no vulnerable parts and a long service life. The "Silver Ball" brand drain valve has a Y series automatic air exhaust device inside, which is very sensitive and can automatically exhaust air, with high working quality.

　　设备刚启动工作时，管道内的空气经过Y系列自动排空气装置排出，低温凝结水进入疏水阀内，凝结水的液位上升，浮球上升，阀门开启，凝结水迅速排出，蒸汽很快进入设备，设备迅速升温，Y系列自动排空气装置的感温液体膨胀，自动排空气装置关闭。疏水阀开始正常工作，浮球随凝结水液位升降，阻汽排水。自由浮球式疏水阀的阀座总处于液位以下，形成水封，无蒸汽泄漏，节能效果好。最小工作压力0.01Mpa，从0.01Mpa至最高使用压力范围之内不受温度和工作压力波动的影响，连续排水。能排饱和温度凝结水，最小过冷度为0℃，加热设备里不存水，能使加热设备达到最佳换热效率。背压率大于85%，是生产工艺加热设备最理想的疏水阀之一。

　　When the equipment starts working, the air in the pipeline is discharged through the Y series automatic air exhaust device. Low temperature condensed water enters the drain valve, the liquid level of condensed water rises, the float rises, the valve opens, and the condensed water is quickly discharged. Steam quickly enters the equipment, and the equipment quickly heats up. The temperature sensing liquid of the Y series automatic air exhaust device expands, and the automatic air exhaust device closes. The drain valve starts working normally, and the float rises and falls with the level of condensed water, blocking steam and draining water. The valve seat of the free floating ball drain valve is always below the liquid level, forming a water seal with no steam leakage and good energy-saving effect. The minimum working pressure is 0.01Mpa, and it is not affected by temperature and working pressure fluctuations within the range of 0.01Mpa to the maximum operating pressure, with continuous drainage. It can discharge saturated temperature condensed water, with a minimum subcooling of 0 ℃, and there is no water in the heating equipment, which can achieve the best heat transfer efficiency of the heating equipment. The back pressure rate is greater than 85%, making it one of the most ideal drain valves for heating equipment in production processes.

　　2.自由半浮球式疏水阀：

　　2. Free semi floating ball drain valve:

　　自由半浮球式疏水阀只有一个半浮球式的球桶为活动部件，开口朝下，球桶即是启闭件，又是密封件。整个球面都可为密封，使用寿命很长，能抗水击，没有易损件，无故障，经久耐用，无蒸汽泄漏。背压率大于80%，能排饱和温度凝结水，最小过冷度为0℃，加热设备里不存水，能使加热设备达到最佳换热效率。

　　The free semi floating ball type drain valve only has one semi floating ball type ball bucket as the moving part, with the opening facing downwards. The ball bucket is both the opening and closing member and the sealing member. The entire spherical surface can be sealed, with a long service life, resistance to water hammer, no vulnerable parts, no faults, durability, and no steam leakage. The back pressure rate is greater than 80%, capable of discharging saturated temperature condensed water, with a minimum subcooling degree of 0 ℃. There is no water in the heating equipment, which can achieve the best heat transfer efficiency of the heating equipment.

　　当装置刚启动时，管道内的空气和低温凝结水经过发射管进入疏水阀内，阀内的双金属片排空元件把球桶弹开，阀门开启，空气和低温凝结水迅速排出。当蒸汽进入球桶内，球桶产生向上浮力，同时阀内的温度升高，双金属片排空元件收缩，球桶漂向阀口，阀门关闭。当球桶内的蒸汽变成凝结水，球桶失去浮力往下沉，阀门开启，凝结水迅速排出。当蒸汽再进入球桶之内，阀门再关闭，间断和连续工作。

　　When the device is just started, the air and low-temperature condensed water in the pipeline enter the drain valve through the launch tube. The bimetallic plate emptying element in the valve opens the ball barrel, and the valve opens, quickly discharging the air and low-temperature condensed water. When steam enters the drum, the drum generates upward buoyancy, and at the same time, the temperature inside the valve increases. The bimetallic strip emptying element contracts, and the drum floats towards the valve port, causing the valve to close. When the steam inside the bucket turns into condensed water, the bucket loses its buoyancy and sinks downwards. The valve opens and the condensed water is quickly discharged. When steam enters the drum again, the valve closes again, and it works intermittently and continuously.

　　3. 杠杆浮球式疏水阀：

　　3. Leverage floating ball drain valve:

　　杠杆浮球式疏水阀基本特点与自由浮球式相同，内部结构是浮球连接杠杆带动阀芯，随凝结水的液位升降进行开关阀门。杠杆浮球式疏水阀利用双阀座增加凝结水排量，可达到体积小排量大，最大疏水量达100吨/小时，是大型加热设备最理想的疏水阀。

　　The basic characteristics of the lever float type drain valve are the same as those of the free float type. The internal structure is that the float is connected to the lever to drive the valve core, and the valve is opened and closed with the rise and fall of the condensate level. The lever floating ball drain valve uses dual valve seats to increase the condensate flow rate, achieving small volume and large flow rate, with a maximum drainage capacity of 100 tons/hour, making it the most ideal drain valve for large heating equipment.

　　4. 倒吊桶式疏水阀：

　　4. Inverted bucket drain valve:

　　倒吊桶式疏水阀内部是一个倒吊桶为液位敏感件，吊桶开口向下，倒吊桶连接杠杆带动阀芯开闭阀门。倒吊桶式疏水阀能排空气，不怕水击，抗污性能好。过冷度小，漏汽率小于3%，最大背压率为75%，连接件比较多，灵敏度不如自由浮球式疏水阀。因倒吊桶式疏水阀是靠蒸汽向上浮力关闭阀门，工作压差小于0.1MPA时，不适合选用。

　　The inside of the inverted bucket drain valve is a liquid level sensitive component. The opening of the bucket is downward, and the connecting lever of the inverted bucket drives the valve core to open and close the valve. The inverted bucket type drain valve can discharge air, is not afraid of water hammer, and has good anti pollution performance. The subcooling degree is small, the steam leakage rate is less than 3%, the maximum back pressure rate is 75%, there are more connections, and the sensitivity is not as good as that of a free floating ball drain valve. Due to the fact that the inverted bucket drain valve relies on steam buoyancy to close the valve, it is not suitable for use when the working pressure difference is less than 0.1MPA.

　　当装置刚启动时，管道内的空气和低温凝结水进入疏水阀内，倒吊桶靠自身重量下坠，倒吊桶连接杠杆带动阀芯开启阀门，空气和低温凝结水迅速排出。当蒸汽进入倒吊桶内，倒吊桶的蒸汽产生向上浮力，倒吊桶上升连接杠杆带动阀芯关闭阀门。倒吊桶上开有一小孔，当一部份蒸汽从小孔排出，另一部份蒸汽产生凝结水，倒吊桶失去浮力，靠自身重量向下沉，倒吊桶连接杠杆带动阀芯开启阀门，循环工作，间断排水。

　　When the device is just started, the air and low-temperature condensed water in the pipeline enter the drain valve, and the inverted bucket falls by its own weight. The connecting lever of the inverted bucket drives the valve core to open the valve, and the air and low-temperature condensed water are quickly discharged. When steam enters the inverted bucket, the steam in the bucket generates upward buoyancy, and the upward connecting lever of the inverted bucket drives the valve core to close the valve. There is a small hole on the inverted bucket. When a part of the steam is discharged from the small hole and another part of the steam produces condensed water, the inverted bucket loses buoyancy and sinks downwards by its own weight. The connecting lever of the inverted bucket drives the valve core to open the valve, which works in a cyclic manner and intermittently discharges water.

　　5. 组合式过热蒸汽疏水阀：

　　5. Combination superheated steam trap:

　　组合式过热蒸汽疏水阀有两个隔离的阀腔，由两根不锈钢管连通上下阀腔，它是由浮球式和倒吊桶式疏水阀的组合，该阀结构先进合理，在过热、高压、小负荷的工作状况下，能够及时地排放过热蒸汽消失时形成的凝结水，有效地阻止过热蒸汽泄漏，工作质量高。最高允许温度为600℃，阀体为全不锈钢，阀座为硬质合金钢，使用寿命长，是过热蒸汽专用疏水阀，取得两项国家专利，填补了国内空白。

　　The combined superheated steam drain valve has two isolated valve chambers connected by two stainless steel pipes. It is a combination of floating ball and inverted bucket drain valves. The valve structure is advanced and reasonable. Under the working conditions of overheating, high pressure, and low load, it can timely discharge the condensed water formed when the hot steam disappears, effectively preventing the leakage of superheated steam and ensuring high working quality. The maximum allowable temperature is 600 ℃, the valve body is made of all stainless steel, and the valve seat is made of hard alloy steel. It has a long service life and is a specialized steam trap for superheated steam. It has obtained two national patents, filling the domestic gap.

　　当凝结水进入下阀腔，副阀的浮球随液位上升，浮球封闭进汽管孔。凝结水经进水导管上升到主阀腔，倒吊桶靠自重下坠，带动阀芯打开主阀门，排放凝结水。当副阀腔的凝结水液位下降时，浮球随液位下降，副阀打开。蒸汽从进汽管进入上主阀腔内的倒吊桶里，倒吊桶产生向上的浮力，倒吊桶带动阀芯关闭主阀门。当副阀腔的凝结水液位再升高时，下一个循环周期又开始，间断排水。

　　When condensed water enters the lower valve chamber, the float of the auxiliary valve rises with the liquid level, and the float seals the inlet pipe hole. The condensed water rises to the main valve chamber through the inlet pipe, and the inverted bucket falls by its own weight, driving the valve core to open the main valve and discharge the condensed water. When the condensate level in the auxiliary valve chamber drops, the float ball follows the decrease in level and the auxiliary valve opens. Steam enters the inverted bucket in the upper main valve chamber through the inlet pipe, and the inverted bucket generates upward buoyancy, which drives the valve core to close the main valve. When the condensate level in the auxiliary valve chamber rises again, the next cycle begins with intermittent drainage.

　　二.热静力型疏水阀

　　II Thermal static type drain valve

　　这类疏水阀是利用蒸汽和凝结水的温差引起感温元件的变形或膨胀带动阀芯启闭阀门。热静力型疏水阀的过冷度比较大，一般过冷度为15度到40度，它能利用凝结水中的一部分显热，阀前始终存有高温凝结水，无蒸汽泄漏，节能效果显著。是在蒸汽管道，伴热管线、小型加热设备，采暖设备，温度要求不高的小型加热设备上，最理想的疏水阀 。

　　This type of drain valve utilizes the temperature difference between steam and condensed water to cause deformation or expansion of the temperature sensing element, which drives the valve core to open and close the valve. The thermal static type drain valve has a relatively high degree of supercooling, generally ranging from 15 degrees to 40 degrees. It can utilize a portion of the sensible heat in the condensed water, and there is always high-temperature condensed water in front of the valve without steam leakage, resulting in significant energy-saving effects. It is the most ideal drain valve for steam pipelines, heat tracing pipelines, small heating equipment, heating equipment, and small heating equipment with low temperature requirements.

　　热静力型疏水阀有膜盒式、波纹管式、双金属片式等。

　　Thermal static type drain valves include membrane type, corrugated tube type, bimetallic plate type, etc.

　　1. 膜盒式疏水阀：

　　1. Diaphragm type drain valve:

　　膜盒式疏水阀的主要动作元件是金属膜盒，膜盒内充有一种汽化温度比水的饱和温度低的液体,有开阀温度低于饱和温度15℃和30℃两种可供选择。膜盒式疏水阀的反应特别灵敏，不怕冻，体积小，耐过热，任意位置都可安装。背压率大于80%，能排不凝结气体，膜盒坚固，使用寿命长，维修方便，使用范围很广。

　　The main operating component of the membrane type drain valve is the metal membrane box, which is filled with a liquid with a vaporization temperature lower than the saturation temperature of water. There are two options for opening the valve: 15 ℃ and 30 ℃ below the saturation temperature. The response of the membrane type drain valve is particularly sensitive, not afraid of freezing, small in size, heat-resistant, and can be installed at any position. The back pressure rate is greater than 80%, it can discharge non condensable gases, the membrane box is sturdy, has a long service life, is easy to maintain, and has a wide range of applications.

　　装置刚启动时，管道出现低温冷凝水，膜盒内的液体处于冷凝状态，阀门处于开启位置。当冷凝水温度渐渐升高，膜盒内充液开始蒸发，膜盒内压力上升，膜片带动阀芯向关闭方向移动，在冷凝水达到饱和温度之前，疏水阀开始关闭。膜盒随蒸汽温度变化控制阀门开关，起到阻汽排水作用。

　　When the device was just started, low-temperature condensed water appeared in the pipeline, and the liquid in the membrane box was in a condensed state, with the valve in the open position. As the temperature of the condensed water gradually increases, the liquid inside the membrane box begins to evaporate, the pressure inside the membrane box rises, and the membrane drives the valve core to move in the closing direction. Before the condensed water reaches saturation temperature, the drain valve begins to close. The membrane box controls the valve opening and closing with changes in steam temperature, playing a role in blocking steam and draining water.

　　2. 波纹管式疏水阀：

　　2. Bellows type drain valve:

　　波纹管式疏水阀的阀芯不锈钢波纹管内充一种汽化温度低于水饱和温度的液体。随蒸汽温度变化控制阀门开关，该阀设有调整螺栓，可根据需要调节使用温度，一般过冷度调整范围低于饱和温度15℃-40℃。背压率大于70%，不怕冻，体积小，任意位置都可安装，能排不凝结气体，使用寿命长。

　　The valve core of the bellows type drain valve is filled with a liquid with a vaporization temperature lower than the saturation temperature of water inside the stainless steel bellows. Control the valve switch with changes in steam temperature. The valve is equipped with adjustment bolts that can adjust the operating temperature as needed. Generally, the undercooling adjustment range is 15 ℃ -40 ℃ below the saturation temperature. Back pressure rate greater than 70%, not afraid of freezing, small size, can be installed at any position, can discharge non condensable gases, and has a long service life.

　　当装置启动时，管道出现冷却凝结水，波纹管内液体处于冷凝状态，阀芯在弹簧的弹力下，处于开启位置。当冷凝水温度渐渐升高，波纹管内充液开始蒸发膨胀，内压增高，变形伸长，带动阀芯向关闭方向移动，在冷凝水达到饱和温度之前，疏水阀开始关闭，随蒸汽温度变化控制阀门开关，阻汽排水。

　　When the device is started, cooling condensate appears in the pipeline, and the liquid inside the corrugated pipe is in a condensed state. The valve core is in the open position under the elastic force of the spring. As the temperature of the condensed water gradually increases, the liquid inside the corrugated tube begins to evaporate and expand, causing an increase in internal pressure, deformation, and elongation, which drives the valve core to move in the closing direction. Before the condensed water reaches saturation temperature, the drain valve begins to close, and the valve switch is controlled according to the change in steam temperature to block steam and drain water.

　　3. 双金属片式疏水阀：

　　3. Bimetallic plate drain valve:

　　双金属片疏水阀的主要部件是双金属片感温元件，随蒸汽温度升降受热变形，推动阀芯开关阀门。双金属片式疏水阀设有调整螺栓，可根据需要调节使用温度，一般过冷度调整范围低于饱和温度15℃-30℃，背压率大于70%，能排不凝结气体，不怕冻，体积小，能抗水击，耐高压，任意位置都可安装。双金属片有疲劳性，需要经常调整。

　　The main component of a bimetallic drain valve is the bimetallic temperature sensing element, which deforms due to the rise and fall of steam temperature and drives the valve core to open and close the valve. The bimetallic strip drain valve is equipped with adjustment bolts, which can adjust the operating temperature according to needs. Generally, the undercooling adjustment range is below the saturation temperature by 15 ℃ -30 ℃, and the back pressure rate is greater than 70%. It can discharge non condensable gases, is not afraid of freezing, has a small volume, can resist water hammer, high pressure, and can be installed at any position. Bimetallic sheets have fatigue and require frequent adjustment.

　　当装置刚启动时，管道出现低温冷凝水，双金属片是平展的，阀芯在弹簧的弹力下，阀门处于开启位置。当冷凝水温度渐渐升高，双金属片感温起元件开始弯曲变形，并把阀芯推向关闭位置。在冷凝水达到饱和温度之前，疏水阀开始关闭。双金属片随蒸汽温度变化控制阀门开关，阻汽排水。

　　When the device is just started, low-temperature condensed water appears in the pipeline. The bimetallic strip is flat, and the valve core is in the open position under the elastic force of the spring. As the temperature of the condensed water gradually increases, the bimetallic sensing element begins to bend and deform, pushing the valve core towards the closed position. Before the condensate reaches saturation temperature, the drain valve begins to close. The bimetallic strip controls the valve opening and closing according to the temperature changes of steam, blocking steam and draining water.

　　三.热动力型疏水阀

　　III Thermal power type drain valve

　　这类疏水阀根据相变原理，靠蒸汽和凝结水通过时的流速和体积变化的不同热力学原理，使阀片上下产生不同压差，驱动阀片开关阀门。因热动力式疏水阀的工作动力来源于蒸汽，所以蒸汽浪费比较大。结构简单、耐水击、最大背为50%，有噪音，阀片工作频繁，使用寿命短。

　　This type of drain valve, based on the principle of phase change, relies on the different thermodynamic principles of the flow rate and volume changes of steam and condensed water passing through, causing different pressure differences between the upper and lower valve plates to drive the valve plate to open and close. Due to the fact that the working power of the thermal power drain valve comes from steam, steam waste is relatively large. Simple structure, shock resistant, maximum back of 50%, noisy, frequent valve operation, short service life.

　　热动力型疏水阀有热动力式（圆盘式）、脉冲式、孔板式等。

　　Thermal power type drain valves include thermal power type (disc type), pulse type, orifice plate type, etc.

　　1. 热动力式疏水阀：

　　1. Thermal power drain valve:

　　热动力式疏水阀内有一个活动阀片，既是敏感件又是动作执行件。根据蒸汽和凝结水通过时的流速和体积变化的不同热力学原理，使阀片上下产生不同压差，驱动阀片开关阀门。漏汽率3%，过冷度为8℃-15℃。

　　There is a movable valve plate inside the thermal power drain valve, which is both a sensitive component and an actuating component. According to the different thermodynamic principles of the flow rate and volume changes of steam and condensed water passing through, different pressure differences are generated above and below the valve plate to drive the valve plate to open and close the valve. The steam leakage rate is 3%, and the subcooling degree is 8 ℃ -15 ℃.

　　当装置启动时，管道出现冷却凝结水，凝结水靠工作压力推开阀片，迅速排放。当凝结水排放完毕，蒸汽随后排放，因蒸汽比凝结水的体积和流速大，使阀片上下产生压差，阀片在蒸汽流速的吸力下迅速关闭。当阀片关闭时，阀片受到两面压力，阀片下面的受力面积小于上面的受力面积，因疏水阀汽室里面的压力来源于蒸汽压力，所以阀片上面受力大于下面，阀片紧紧关闭。当疏水阀汽室里面的蒸汽降温成凝结水，汽室里面的压力消失。凝结水靠工作压力推开阀片，凝结水又继续排放,循环工作，间断排水。

　　When the device is started, cooling condensate appears in the pipeline, and the condensate is quickly discharged by pushing open the valve plate under working pressure. When the condensed water is discharged, the steam is then discharged. Due to the larger volume and flow rate of steam compared to condensed water, a pressure difference is generated between the upper and lower parts of the valve plate, and the valve plate quickly closes under the suction of the steam flow rate. When the valve plate is closed, it is subjected to pressure from both sides, and the force area below the valve plate is smaller than the force area above it. Because the pressure inside the steam chamber of the drain valve comes from steam pressure, the force on the top of the valve plate is greater than that below it, and the valve plate is tightly closed. When the steam in the steam trap chamber cools down into condensed water, the pressure inside the chamber disappears. The condensate is pushed open by the working pressure, and the condensate continues to be discharged, circulating and intermittently draining.

　　2. 圆盘式蒸汽保温型疏水阀：

　　2. Disc type steam insulated drain valve:

　　圆盘式蒸汽保温型疏水阀的工作原理和热动力式疏水阀相同，它在热动力式疏水阀的汽室外面增加一层外壳。外壳内室和蒸汽管道相通，利用管道自身蒸汽对疏水阀的主汽室进行保温。使主汽室的温度不易降温，保持汽压，疏水阀紧紧关闭。当管线产生凝结水，疏水阀外壳降温，疏水阀开始排水；在过热蒸汽管线上如果没有凝结水产生，疏水阀不会开启，工作质量高。阀体为合金钢，阀芯为硬质合金，该阀最高允许温度为550℃，经久耐用，使用寿命长，是高压、高温过热蒸汽专用疏水阀。

　　The working principle of the disc type steam insulated drain valve is the same as that of the thermal power drain valve, which adds a layer of shell outside the steam chamber of the thermal power drain valve. The inner chamber of the shell is connected to the steam pipeline, and the main steam chamber of the drain valve is insulated using the pipeline's own steam. Make it difficult for the temperature of the main steam chamber to cool down, maintain steam pressure, and tightly close the drain valve. When condensation occurs in the pipeline, the shell of the drain valve cools down and the drain valve begins to drain water; If there is no condensed water generated on the superheated steam pipeline, the drain valve will not open, and the working quality is high. The valve body is made of alloy steel, and the valve core is made of hard alloy. The maximum allowable temperature of this valve is 550 ℃, which is durable and has a long service life. It is a special drain valve for high-pressure and high-temperature superheated steam.

　　3. 脉冲式疏水阀：

　　3. Pulse type drain valve:

　　脉冲式疏水阀有两个孔板根据蒸汽压降变化调节阀门开关，即使阀门完全关闭入口和出口也是通过第一、第二个小孔相通，始终处于不完全关闭状态，蒸汽不断溢出，漏汽量大。该疏水阀动作频率很高，磨损厉害、寿命较短。体积小、耐水击，能排出空气和饱和温度水，接近连续排水，最大背压25%，因此使用者很少。

　　The pulse type drain valve has two orifice plates that adjust the valve opening and closing according to changes in steam pressure drop. Even if the valve is completely closed, the inlet and outlet are connected through the first and second small holes, always in an incomplete closed state, causing steam to continuously overflow and a large amount of steam leakage. This drain valve has a high operating frequency, severe wear, and a short lifespan. Small size, shock resistant, capable of discharging air and saturated temperature water, close to continuous drainage, with a maximum back pressure of 25%, therefore few users.

　　4. 孔板式疏水阀：

　　4. Orifice type drain valve:

　　孔板式疏水阀是根据不同的排水量，选择不同孔径的孔板，达到控制排水量的目的。结构简单，选择不合适会出现排水不及或大量跑汽，不适用于间歇生产的用汽设备或冷凝水量波动大的用汽设备。

　　The orifice plate drain valve selects orifice plates with different diameters according to different drainage volumes to achieve the purpose of controlling drainage volume. The structure is simple, and improper selection may result in insufficient drainage or a large amount of steam leakage. It is not suitable for intermittent production steam equipment or steam equipment with large fluctuations in condensate water volume.

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