【正文】 mp spindle and around packing box between end cover39。s liquid divulging and the air enters in the pump, achieves seals and prevents the air admission to cause the pump cavitation goal. the axis seals form: Namely has skeleton39。s prime task parameter 1. Current capacity: Namely the pump in unit of time discharges the liquid quantity, usually indicated with the Unit of volume that mark Q, the unit has m3/h, m3/s, l/s and so on, 2. Lifting: The transportation unit weight39。s increment, indicated with H, the unit is m. 3. Rotational speed: Pump39。s net positive suction head is expressed that pump39。s main parameter,  uses the symbolic representation. 5. Power and efficiency: Pump39。s output. Pump39。s length, the size, the shape, the surface roughness, as well as liquid speed of flow and characteristic.2. Volumetric loss: volumetric loss was already obtained the energy liquid to have a part to flee the result which in the pump the class and leaked outward. Pump39。s speed changeProportionality law 1. Centrifugal pump39。s speed change, is a new important energy conservation way. 2. proportionality law expression: In the formula, Q, H, N pump39。s ratio rotation Compared to the rotation is the prehensive parameter which derives by the law of similarity, it is the operating mode function, to a pump, the different operating mode has differently pared to the rotation, for ease of carries on the parison to the different type pump39。s rotational speed, calculates the ns number, determines pump39。s cavitation andinspirationcharacteristic phenomenons The pumping station transportation medium39。s operating performance: When the cavitation develops the certain extent, the  steam bubble produces massively, will stop up the flow channel, will cause pump39。s material quality: Is mainly nearby the leaf blade entrance the metal weary disintegration.3. centrifugal pump39。s permission net positive suction head is: = 4. Enhances the centrifugal pump anticavitation performance the method to include: (1). I mprovement machine pump structure, reduces, is machine the pump design question. (2). Enhancement installment effective net positive suction head. Most mainly the most monly used method uses the irrigation inspiration installment. In addition, reduces the inspiration pipeline resistance loss as far as possible, reduces the liquid the saturated steam tension, namely when design inspiration pipeline selects caliber big as far as possible, length short, the bend and valve few, transportation liquid temperature as far as possible low and so on measures, may enhance the installment the effective cavitation remainder.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 operating procedure 1. Centrifugal pump starts the inspection (1) Electrical machinery overhaul, before connecting the shaft coupling, inspects electrical machinery39。s inlet valve, closes pump39。s seal condition and oil seal opening. attention: The hot oil pump wants evenly before the start preheating. 2. centrifugal pump39。s outlet valve slowly.(2) shuts off electrical machinery39。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。而且，隨著科學(xué)技術(shù)的發(fā)展，泵的應(yīng)用領(lǐng)域正在迅速擴(kuò)大，根據(jù)國(guó)家統(tǒng)計(jì)，泵的耗電量都約占全國(guó)總發(fā)電量的1/5,可見(jiàn)泵是當(dāng)然的耗能大戶。 驅(qū)動(dòng)機(jī)通過(guò)泵軸帶動(dòng)葉輪旋轉(zhuǎn)產(chǎn)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(jīng)蝸殼收集送入排出管。在液體被甩向葉輪出口的同時(shí),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(chǎn)生了壓差,吸液罐中的液體在這個(gè)壓差作用下,不斷地經(jīng)吸入管路及泵的吸入室進(jìn)入葉輪中。 :即泵的殼體,包括吸入室和壓出室。 ②壓出室:它的作用是收集液體,并把它送入下級(jí)葉輪或?qū)蚺懦龉?與此同時(shí)降低液體的速度,使動(dòng)能進(jìn)一步變成壓力能。2．葉輪:它是離心泵內(nèi)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(dòng)機(jī)帶動(dòng)旋轉(zhuǎn),通過(guò)葉片把原動(dòng)機(jī)的能量傳給液體。 ②按照液體相對(duì)于旋轉(zhuǎn)軸線的流動(dòng)方向分類：徑流式葉輪、軸流式葉輪和混流式葉輪。 3．軸:是傳遞機(jī)械能的重要零件,原動(dòng)機(jī)的扭矩通過(guò)它傳給葉輪。泵軸靠?jī)啥溯S承支承，在泵中作高速回轉(zhuǎn)，因而泵軸要承載能力大、耐磨、耐腐蝕。:是安裝在轉(zhuǎn)動(dòng)的葉輪和靜止的泵殼（中段和導(dǎo)葉的組合件）之間的密封裝置。：軸套是用來(lái)保護(hù)泵軸的，使之不受腐蝕和磨損。：泵軸和前后端蓋間的填料函裝置簡(jiǎn)稱為軸封，主要防止泵中的液體泄漏和空氣進(jìn)入泵中，以達(dá)到密封和防止進(jìn)氣引起泵氣蝕的目的。 . :即泵在單位時(shí)間內(nèi)排出的液體量,通常用體積單位表示,符號(hào)Q,單位有m3/h,m3/s,l/s等, :輸送單位重量的液體從泵入口處(泵進(jìn)口法蘭)到泵出口處(泵出口法蘭),其能量的增值,用H表示,單位為m. :泵的轉(zhuǎn)速是泵每分鐘旋轉(zhuǎn)的次數(shù),用N來(lái)表示。 :離心泵的汽蝕余量是表示泵的性能的主要參數(shù),用符號(hào)表示。泵的輸出功率為有效功率。泵內(nèi)所有損失可分為以下幾項(xiàng)： 由液體在泵內(nèi)的沖擊、渦流和表面摩擦造成的。液體流經(jīng)所接觸的流道總會(huì)出現(xiàn)表面摩擦，由此而產(chǎn)生的能量損失主要取決于流道的長(zhǎng)短、大小、形狀、表面粗糙度，以及液體的流速和特性。泵的容積效率一般為0．93～0．98。 機(jī)械損失指葉輪蓋板側(cè)面與泵殼內(nèi)液體間的摩擦損失，即圓盤(pán)損失，以及泵軸在盤(pán)根、軸承及平衡裝置等機(jī)械部件運(yùn)動(dòng)時(shí)的摩擦損失，一般以前者為主。目前,采用變頻調(diào)速電機(jī)來(lái)實(shí)現(xiàn)離心泵的變速,是一條新的重要的節(jié)能途徑。在選泵時(shí)，可根據(jù)工作需要的Q、H和結(jié)合電機(jī)的轉(zhuǎn)速，計(jì)算出ns數(shù)，大致確定泵的類型。七、離心泵的汽蝕與吸入特性泵所輸送介質(zhì)的液體狀態(tài)和氣體是能夠相互轉(zhuǎn)化的，轉(zhuǎn)化的條件就是壓力和溫度。溫度越高，液體的汽化壓力越高。這些氣泡隨液流向前運(yùn)動(dòng)至高壓區(qū)時(shí)，氣泡周圍的高壓液體使氣泡急劇地縮小以至凝結(jié)。上述過(guò)程稱為汽蝕。 (2).對(duì)泵的工作性能有影響:當(dāng)汽蝕發(fā)展到一定程度時(shí),汽泡大量產(chǎn)生,會(huì)堵塞流道,使泵的流量、揚(yáng)程、效率等均明顯下降。: (1).泵發(fā)生汽蝕的基本條件是:葉片入口處的最低液流壓力≤該溫度下液體的汽化壓力。 (3).泵必需的汽蝕余量:液流從泵入口到葉輪內(nèi)最低壓力點(diǎn)K處的全部能量損失,用表示。 (2).. 此外，盡量減少吸入管路阻力損失，降低液體的飽和蒸汽壓，即在設(shè)計(jì)吸入管路時(shí)盡可能選用管徑大些，長(zhǎng)度短些，彎頭和閥門(mén)少些，輸送液體的溫度盡可能低些等措施，都可提高裝置的有效氣蝕余量。 ②流體流入和流出葉輪的方向和速度不同而產(chǎn)生的動(dòng)反力A2,其方向與A1相反,所以總軸向力A=A1A2,方向一般與A1相同(一般A2較小)。②開(kāi)平衡孔或裝平衡管: A:在葉輪輪盤(pán)上相對(duì)于吸入口處開(kāi)幾個(gè)平衡孔。③采用平衡葉片:在葉輪盤(pán)背面鑄幾條徑向筋片,筋片帶動(dòng)葉輪背面間隙內(nèi)的流體加速旋轉(zhuǎn),增大離心力,從而使葉輪背面壓力顯著降低。一般小型的單吸泵中止推軸承可以承受全部的軸向力，防止泵軸竄動(dòng)。(2)檢查泵出入口管線及附屬管線，法蘭，閥門(mén)安裝是否符合要求，地腳螺栓及地線是否良好，聯(lián)軸器是否裝好。(4)檢查潤(rùn)滑油油位是否正常，無(wú)油加油，并檢查潤(rùn)滑油（脂）的油質(zhì)性質(zhì)。注意冷卻水不宜過(guò)大或過(guò)小，過(guò)大會(huì)造成浪費(fèi)，過(guò)小則冷卻效果差。(6)打開(kāi)泵的入口閥，關(guān)閉泵的出口閥，并打開(kāi)壓力表手閥。注意：熱油泵在啟動(dòng)前要均勻預(yù)熱。(2)當(dāng)泵出口壓力大于操作壓力時(shí)，檢查各部運(yùn)轉(zhuǎn)正常，逐漸打開(kāi)出口閥。(4)啟動(dòng)時(shí)，注意人不要面向聯(lián)軸器，以防飛出傷人。(2)切斷電機(jī)的電源。(4)停車后，不能馬上停冷卻水，應(yīng)泵的溫度的降到80度以下方可停水。(1)離心泵在運(yùn)轉(zhuǎn)時(shí)避免空轉(zhuǎn)。(3)嚴(yán)禁用水沖電機(jī)。：“成功就是目標(biāo)的達(dá)成，其他都是這句話的注釋。：“一次做好一件事的人比同時(shí)涉獵多個(gè)領(lǐng)域的人要好得多。培養(yǎng)重點(diǎn)思維從重點(diǎn)問(wèn)題突破，是高效能人士思考的一項(xiàng)重要習(xí)慣。相反，如果他抓住了主要矛盾，解決問(wèn)題就變得容易