1真(zhen)空(kong)泵的工作壓強應該滿足真(zhen)空(kong)設備(bei)的極限真(zhen)空(kong)及工作壓強要求。通常(chang)選擇泵的真(zhen)空(kong)度(du)要高于真(zhen)空(kong)設備(bei)的直空(kong)度(du)半個(ge)到一(yi)個(ge)數量級(ji)
2正確地(di)選擇(ze)真空(kong)泵的工作(zuo)點
3真空頸(jing)在其(qi)工(gong)作壓強下,應能排走真空設備工(gong)藝過程中(zhong)產生(sheng)的全部氣(qi)體量。
4.正確地組(zu)合(he)真(zhen)空(kong)(kong)(kong)泵(beng)(beng)。由于(yu)(yu)真(zhen)空(kong)(kong)(kong)泵(beng)(beng)具有(you)(you)選(xuan)擇性抽(chou)氣(qi)(qi)(qi)的特點,當選(xuan)用(yong)一種泵(beng)(beng)不能(neng)(neng)滿足抽(chou)氣(qi)(qi)(qi)要求時,需(xu)(xu)要幾種泵(beng)(beng)組(zu)合(he)起來,互相補充才能(neng)(neng)滿足抽(chou)氣(qi)(qi)(qi)要求。另(ling)外,有(you)(you)的直空(kong)(kong)(kong)泵(beng)(beng)不能(neng)(neng)在大(da)(da)氣(qi)(qi)(qi)壓(ya)(ya)下工作,需(xu)(xu)要預抽(chou)真(zhen)空(kong)(kong)(kong);有(you)(you)的真(zhen)空(kong)(kong)(kong)泵(beng)(beng)出口壓(ya)(ya)強低于(yu)(yu)大(da)(da)氣(qi)(qi)(qi)壓(ya)(ya),需(xu)(xu)要前(qian)級泵(beng)(beng),故都需(xu)(xu)要把泵(beng)(beng)組(zu)全起來使用(yong)。
5真(zhen)空(kong)設備(bei)對(dui)油污(wu)染的要求(qiu)。若設備(bei)嚴(yan)格要求(qiu)無油時,應該選(xuan)各種無油泵(beng)(beng),如(ru):水環(huan)泵(beng)(beng)、分(fen)子篩吸附泵(beng)(beng)、低溫(wen)泵(beng)(beng)等。如(ru)果要求(qiu)不嚴(yan)格,可(ke)以(yi)選(xuan)擇有(you)油泵(beng)(beng),加上一些防(fang)油污(wu)染措施,如(ru)加冷阱、障板、擋油阱等,也能達到清潔真(zhen)空(kong)要求(qiu)
6.了解被抽(chou)(chou)氣(qi)(qi)(qi)體成(cheng)分(fen),氣(qi)(qi)(qi)體中含(han)不(bu)含(han)可凝蒸氣(qi)(qi)(qi),有(you)(you)無(wu)顆粒灰塵(chen),有(you)(you)無(wu)腐(fu)蝕(shi)性等。選擇真空泵時,需要知道氣(qi)(qi)(qi)體成(cheng)分(fen),針對被抽(chou)(chou)氣(qi)(qi)(qi)體選擇相應的泵。如(ru)果(guo)氣(qi)(qi)(qi)體中含(han)有(you)(you)蒸氣(qi)(qi)(qi)、顆粒、及腐(fu)蝕(shi)性氣(qi)(qi)(qi)體,應該考慮在泵的進(jin)氣(qi)(qi)(qi)口管路上(shang)安(an)裝輔助設備,如(ru)冷凝器、除塵(chen)器等。
7真空泵(beng)排出來的油(you)(you)蒸氣對環境(jing)(jing)的影響如何。如果環境(jing)(jing)不允許有污染,可以選(xuan)無油(you)(you)真空泵(beng)。
水環式真空泵的選擇
一、泵類型的確定
水(shui)環(huan)真(zhen)空(kong)(kong)泵(beng)主要用于(yu)粗、低真(zhen)空(kong)(kong)、抽氣(qi)量大的工(gong)藝過程中。它主要用來抽除空(kong)(kong)氣(qi)和其它無(wu)腐蝕、不(bu)溶于(yu)水(shui),
含有(you)(you)少(shao)量固體(ti)顆粒的(de)氣(qi)體(ti),以便在密閉容(rong)器中(zhong)形成(cheng)真空。所吸氣(qi)體(ti)中(zhong)允許混(hun)有(you)(you)少(shao)量液(ye)體(ti)。它(ta)被廣(guang)泛應用于機械、
制藥、食品、石油化(hua)工等行業中。
的類型(xing)主要(yao)由(you)工(gong)作(zuo)所需(xu)的氣(qi)量、真空(kong)度或排氣(qi)壓力而定。泵工(gong)作(zuo)時,需(xu)要(yao)注意以下兩個方面:
1.盡可能要求在(zai)高效區內,也就是在(zai)臨界真空(kong)度或(huo)臨界排氣壓(ya)力的區域內運行。
2應避(bi)免在(zai)(zai)(zai)(zai)最大(da)(da)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)或最大(da)(da)排氣壓(ya)(ya)力(li)附(fu)近(jin)運行。在(zai)(zai)(zai)(zai)此(ci)區域內運行,不(bu)僅效率極低(di),而且工(gong)作很不(bu)穩(wen)定易(yi)產(chan)生振動(dong)(dong)和(he)噪音。對于真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)較(jiao)(jiao)高的(de)(de)(de)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)泵(beng)而言,在(zai)(zai)(zai)(zai)此(ci)區域之(zhi)內運行,往往還會發生汽蝕現象(xiang),產(chan)生這(zhe)種現象(xiang)的(de)(de)(de)明顯標志是泵(beng)內有噪音和(he)振動(dong)(dong)。汽蝕會導(dao)致(zhi)泵(beng)體、葉輪(lun)等零件的(de)(de)(de)損(sun)壞(huai),以(yi)致(zhi)泵(beng)無法(fa)工(gong)作。根據以(yi)上(shang)原則,當泵(beng)所需的(de)(de)(de)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)或氣體壓(ya)(ya)力(li)不(bu)高時,可(ke)優先在(zai)(zai)(zai)(zai)單級泵(beng)中(zhong)選(xuan)(xuan)取。如果真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)或排氣壓(ya)(ya)力(li)較(jiao)(jiao)高,單級泵(beng)往往不(bu)能滿足,或者,要(yao)求泵(beng)在(zai)(zai)(zai)(zai)較(jiao)(jiao)高真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)情況(kuang)下仍有較(jiao)(jiao)大(da)(da)氣量,即要(yao)求性能曲線在(zai)(zai)(zai)(zai)較(jiao)(jiao)高真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)時較(jiao)(jiao)平坦(tan),可(ke)選(xuan)(xuan)用(yong)兩(liang)級泵(beng)。如果真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)度(du)(du)要(yao)求在(zai)(zai)(zai)(zai)一710mmH以(yi)上(shang),可(ke)選(xuan)(xuan)用(yong)水環(huan)大(da)(da)氣質射泵(beng)或水環(huan)羅茨(ci)真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)機組(zu)作為抽真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)裝置如果只作真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)泵(beng)用(yong),則選(xuan)(xuan)用(yong)單作用(yong)泵(beng)比(bi)較(jiao)(jiao)好。因(yin)為單作用(yong)泵(beng)的(de)(de)(de)構造簡單,容(rong)易(yi)制造和(he)維護,且在(zai)(zai)(zai)(zai)高真(zhen)(zhen)(zhen)(zhen)空(kong)(kong)(kong)情況(kuang)
