【正文】 . 17 。：泵軸和前后端蓋間的填料函裝置簡稱為軸封，主要防止泵中的液體泄漏和空氣進入泵中，以達到密封和防止進氣引起泵氣蝕的目的。：軸套是用來保護泵軸的，使之不受腐蝕和磨損。:是安裝在轉動的葉輪和靜止的泵殼（中段和導葉的組合件）之間的密封裝置。泵軸靠兩端軸承支承，在泵中作高速回轉，因而泵軸要承載能力大、耐磨、耐腐蝕。 3．軸:是傳遞機械能的重要零件,原動機的扭矩通過它傳給葉輪。 ②按照液體相對于旋轉軸線的流動方向分類：徑流式葉輪、軸流式葉輪和混流式葉輪。2．葉輪:它是離心泵內傳遞能量給液體的唯一元件,葉輪用鍵固定于軸上，隨軸由原動機帶動旋轉,通過葉片把原動機的能量傳給液體。 ②壓出室:它的作用是收集液體,并把它送入下級葉輪或導向排出管,與此同時降低液體的速度,使動能進一步變成壓力能。 :即泵的殼體,包括吸入室和壓出室。在液體被甩向葉輪出口的同時,葉輪入口中心處形成了低壓,在吸液罐和葉輪中心處的液體之間就產生了壓差,吸液罐中的液體在這個壓差作用下,不斷地經吸入管路及泵的吸入室進入葉輪中。 驅動機通過泵軸帶動葉輪旋轉產生離心力,在離心力作用下,液體沿葉片流道被甩向葉輪出口,液體經蝸殼收集送入排出管。而且，隨著科學技術的發(fā)展，泵的應用領域正在迅速擴大，根據國家統(tǒng)計，泵的耗電量都約占全國總發(fā)電量的1/5,可見泵是當然的耗能大戶。s temperature only then cut off the water supply falling to 80 degrees below. (5) according to the need, closes the inlet valve, the pump body blows off.4. centrifugal pump operates when matters needing attention (1) centrifugal pump when revolution avoids the idle operation. (2) avoids when closes the outlet valve the long time revolution. (3) refuses the water used battery (4) centrifugal pump must in close in outlet valve39。s outlet valve slowly.(2) shuts off electrical machinery39。s seal condition and oil seal opening. attention: The hot oil pump wants evenly before the start preheating. 2. centrifugal pump39。s inlet valve, closes pump39。s operating procedure 1. Centrifugal pump starts the inspection (1) Electrical machinery overhaul, before connecting the shaft coupling, inspects electrical machinery39。5. axial force balancing unit(1). axial force production reason ①Around because the impeller the both sides the fluid pressure distributed situation different (wheel cap lateral pressure is low,  wheel disk pressure high) causes axial force A1, its direction for from impeller back side direction impeller eye. ②The fluid flows in and flows out dynamical reaction A2 which impeller39。s inspiration characteristic: (1). Pump has the cavitation basic condition is: Under leaf blade entrance lowest liquid flow pressure = this temperature liquid vaporization pressure .(2). effective net positive suction head: The pump entry (potential head is the entire flood peak which zero) the liquid has subtracts the value which the vaporization delivery head remains only, with expression. (3). pump essential net positive suction head: Liquid flow from pump inlet to impeller in minimal pressure point of force K place plete energy loss, with expression. (4). With and difference and relation: Pump not cavitation The pump starts the cavitation Pump serious cavitation (5). regarding a pump, to guarantee that its safe operation does not have the cavitation, must the net positive suction head also be supposed to add a security allowance regarding the pump, therefore, pump39。s current capacity, lifting, the efficiency and so on obviously to drop. (3). will have the destruction to flow channel39。s liquid condition and the gas are can transform mutually, the transformed condition is the pressure and the temperature. Under certain temperature, the liquid starts the critical pressure which vaporizes for the vaporization pressure. The temperature is higher, the liquid vaporization pressure is higher. Pump when revolution, if its overflow part local region (for example impeller blade import later somewhere), the liquid absolute pressure drops when pulled out delivers the liquid at that time under the temperature vaporization pressure, the liquid then in this place starts to vaporize, the bubble formation (air bubble internal pressure approximately was equal to vaporization pressure). When these air bubbles along with liquid flow forward motion to high pressure region, down to around the air bubble highpressured liquid causes the air bubble to reduce suddenly congeals. While air bubble vanishing, the liquid particle by the high speed packing hole, occurs hits mutually forms the intense pressure surge, causes the overflow part to receive the corrosion and the destruction. The above process is called the cavitation. 2. Cavitation will cause serious results: (1). has the vibration and the noise. (2). is influential to pump39。s type approximately. At that time, used the positive displacement pump generally, at that time, used the centrifugal pump, the interflow pump, the axial flow pump and so on.Seventh,centrifugal pump39。s performance and the structure, the application optimum condition (the peak efficiency spot) the ratio rotation represents this pump. When chooses the pump, may according to job requirement Q, H and unifies electrical machinery39。s rated flow, lifting and shaft power The subscript 1,2 express the different rotational speed separately n rotational speedSixth, centrifugal pump39。s speed change: