良工閥門：呼吸閥和安全閥，你了解多少？

　　What do you know about Lianggong Valve: Breathing Valve and Safety Valve?

　　呼吸閥和安全閥都是儲罐的安全附件，用于控制儲罐的壓力，設(shè)計原理有很多相似之處，但有一個本質(zhì)的區(qū)別，呼吸閥是化工儲罐中常見的氣體壓力保護(hù)裝置，應(yīng)用于正常運行狀態(tài)下的安全附件，隨著儲罐日常的日常運行使用而調(diào)節(jié)動作。安全閥是緊急狀態(tài)下的安全保護(hù)附件，當(dāng)儲罐的安全受到威脅時才會動作。

　　Breathing valves and safety valves are both safety accessories for storage tanks, used to control the pressure of the tank. There are many similarities in design principles, but there is an essential difference. Breathing valves are common gas pressure protection devices in chemical storage tanks, applied as safety accessories under normal operating conditions, and adjust their actions with the daily operation and use of the tank. The safety valve is a safety protection accessory in emergency situations, which only operates when the safety of the storage tank is threatened.

　　1. 呼吸閥

　　1. Breathing valve

　　呼吸閥是一種用于常壓或低壓儲罐(注:操作壓力范圍在全真空到103.4kPag之間)的安全設(shè)施。它可以保持常壓或低壓儲罐中的壓力始終處于正常狀態(tài),用來降低常壓或低壓儲罐內(nèi)揮發(fā)性液體的蒸發(fā)損失,并保護(hù)儲罐免受超壓或超真空度的破壞。

　　A breathing valve is a safety device used for atmospheric or low-pressure storage tanks (note: the operating pressure range is between full vacuum and 103.4kPag). It can maintain the pressure in atmospheric or low-pressure storage tanks in a normal state, reducing the evaporation loss of volatile liquids in atmospheric or low-pressure storage tanks and protecting the tanks from damage caused by overpressure or vacuum.

　　呼吸閥種類很多，但原理基本相同，內(nèi)部結(jié)構(gòu)是由一個低壓安全閥(即呼氣閥)和一個真空閥(即吸氣閥)組合而成的,習(xí)慣上把它稱為呼吸閥。常用的呼吸閥可分為兩種基本類型:重力式呼吸閥(或稱閥盤式)和先導(dǎo)式呼吸閥。

　　There are many types of breathing valves, but their principles are basically the same. The internal structure is composed of a low-pressure safety valve (i.e. exhalation valve) and a vacuum valve (i.e. inhalation valve), which are commonly referred to as breathing valves. The commonly used breathing valves can be divided into two basic types: gravity breathing valves (or valve discs) and pilot operated breathing valves.

　　重力式呼吸閥它利用閥盤的重量來控制儲罐的排氣正壓和吸氣負(fù)壓，呼吸閥不工作時雙閥盤關(guān)閉處于密閉狀態(tài)，當(dāng)罐內(nèi)補(bǔ)充介質(zhì)罐內(nèi)液位升高，上部氣體空間減小，內(nèi)部壓力升高，當(dāng)壓力超過呼吸閥的正壓閥盤重力時，閥盤被頂開，氣體從泄壓孔溢出；當(dāng)罐內(nèi)流出介質(zhì)液位下降，上部氣體空間增大，壓力下降，產(chǎn)生負(fù)壓，當(dāng)罐內(nèi)產(chǎn)生的負(fù)壓壓力大于負(fù)壓閥盤重力時，外部大氣將頂開負(fù)壓閥盤，進(jìn)入罐內(nèi)使罐內(nèi)壓力平衡，保護(hù)儲罐安全。

　　Gravity breathing valve uses the weight of the valve disc to control the exhaust positive pressure and suction negative pressure of the storage tank. When the breathing valve is not working, the dual valve disc is closed and in a sealed state. When the liquid level in the tank is replenished with medium, the upper gas space decreases and the internal pressure increases. When the pressure exceeds the gravity of the positive pressure valve disc of the breathing valve, the valve disc is pushed open and gas overflows from the pressure relief hole; When the liquid level of the medium flowing out of the tank decreases, the upper gas space increases, the pressure decreases, and negative pressure is generated. When the negative pressure pressure generated in the tank is greater than the gravity of the negative pressure valve disc, the external atmosphere will push open the negative pressure valve disc and enter the tank to balance the pressure inside and protect the safety of the storage tank.

　　先導(dǎo)式呼吸閥由一個主閥和一個導(dǎo)閥組成,兩閥先后動作來聯(lián)合完成呼氣和吸氣動作。由于導(dǎo)閥采用薄膜結(jié)構(gòu),薄膜面積大,故在很低的工作壓力下,仍可輸出足夠的作用力來控制主閥的動作。在導(dǎo)閥開啟前,主閥不受控制流的作用,關(guān)閉嚴(yán)密,無泄漏現(xiàn)象。

　　A pilot operated breathing valve consists of a main valve and a pilot valve, which act sequentially to jointly complete exhalation and inhalation actions. Due to the use of a thin film structure and a large film area, the pilot valve can still output sufficient force to control the action of the main valve at very low working pressures. Before the pilot valve is opened, the main valve is not controlled by the flow and is tightly closed without any leakage.

　　呼吸閥在日常的維護(hù)中要保持閥座、閥盤的清潔，帶阻火器的呼吸閥還要保持阻火器的部分的通暢，否則容易造成事故。

　　In daily maintenance, the valve seat and disc of the breathing valve should be kept clean, and the breathing valve with a flame arrester should also keep the flame arrester part unobstructed, otherwise accidents may occur.

　　2. 安全閥

　　2. Safety valve

　　安全閥是一種自動機(jī)構(gòu)，原理與呼吸閥類似，在介質(zhì)壓力超過工作壓力時自動打開，在壓力回降到工作壓力或低于工作壓力后又能自動關(guān)閉。常用與壓力容器，壓縮機(jī)、容積泵的管道中。

　　A safety valve is an automatic mechanism that operates similarly to a breathing valve. It opens automatically when the medium pressure exceeds the working pressure and closes automatically when the pressure drops back to or below the working pressure. Commonly used in pipelines of pressure vessels, compressors, and positive displacement pumps.

　　按照結(jié)構(gòu)類型分類主要有重力式安全閥、彈簧式安全閥、先導(dǎo)式安全閥。

　　Classified by structural type, there are mainly gravity safety valves, spring safety valves, and pilot operated safety valves.

　　重力式安全閥利用重錘的重力來封閉通道和控制設(shè)定壓力，如圖所示。

　　The gravity type safety valve uses the weight of a heavy hammer to close the channel and control the set pressure, as shown in the figure.

　　彈簧式安全閥依靠彈簧彈力用閥盤施加壓力來封閉通道和控制設(shè)定壓力。如果出口有一定的壓力，需要帶背壓平衡裝置的安全閥，按照其形式又可分為活塞式和波紋管式。

　　Spring type safety valves rely on the elastic force of the spring to apply pressure to the valve disc to close the channel and control the set pressure. If there is a certain pressure at the outlet, a safety valve with a back pressure balancing device is required, which can be divided into piston type and bellows type according to its form.

　　先導(dǎo)式安全閥

　　Pilot operated safety valve

　　先導(dǎo)式安全閥也稱脈沖式安全閥，原理與先導(dǎo)式呼吸閥相似，其設(shè)定壓力由導(dǎo)閥控制,動作特性基本不受背壓影響。由兩部分組成導(dǎo)閥和主閥，主閥作用于壓力容器的泄壓通道，導(dǎo)閥用于控制主閥的啟閉，導(dǎo)閥其實就是一個小號的彈簧式安全閥，通過平衡管將主閥上下連通，兩端形成穩(wěn)定狀態(tài)，當(dāng)容器內(nèi)壓力上升，壓力通過平衡管傳導(dǎo)至導(dǎo)閥，當(dāng)壓力超過導(dǎo)閥設(shè)定值，導(dǎo)閥關(guān)閉平衡管至主閥上氣室的通道，并同時打開主閥上氣室對空泄壓，讓主閥上下形成壓差從而打開主閥。先導(dǎo)式安全閥體積小，壓力控制范圍廣，精度高，不受背壓影響。但其系統(tǒng)回路相對較復(fù)雜，耐用度受介質(zhì)影響，成本較高。

　　Pilot operated safety valve, also known as pulse operated safety valve, has a principle similar to that of pilot operated breathing valve. Its set pressure is controlled by the pilot valve, and its operating characteristics are basically not affected by back pressure. The main valve consists of two parts: a pilot valve and a main valve. The main valve acts on the pressure relief channel of the pressure vessel, and the pilot valve is used to control the opening and closing of the main valve. The pilot valve is actually a small spring-loaded safety valve, which connects the upper and lower parts of the main valve through a balance pipe, forming a stable state at both ends. When the pressure in the container rises, the pressure is transmitted to the pilot valve through the balance pipe. When the pressure exceeds the set value of the pilot valve, the pilot valve closes the channel from the balance pipe to the upper chamber of the main valve, and at the same time opens the upper chamber of the main valve to release air pressure, creating a pressure difference between the upper and lower parts of the main valve and opening the main valve. Pilot operated safety valves have small volume, wide pressure control range, high accuracy, and are not affected by back pressure. But its system circuit is relatively complex, durability is affected by the medium, and the cost is high.

　　安全閥在使用中如果發(fā)現(xiàn)有動作需引起重視，盡快查找原因，防止出現(xiàn)超壓事故。且安全閥需要每年交由有資質(zhì)單位進(jìn)行校驗。

　　If there is any movement of the safety valve during use, it should be taken seriously and the cause should be identified as soon as possible to prevent overpressure accidents. And the safety valve needs to be verified annually by a qualified unit.

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