在管道工程中，正確選用電動閥門是(shi)滿(man)足使用(yong)(yong)要求的保證條件之(zhi)一。如果對(dui)所使用(yong)(yong)的電動閥(fa)門選擇不(bu)當,不(bu)僅會影響使用(yong)(yong),而且還(huan)會帶(dai)來不(bu)良后果或嚴重的損 失,因此,在管道工程設(she)計(ji)中應正(zheng)確選用(yong)(yong)電動閥(fa)門。 

電動閥門除應注意管道參數外，尚應特別注意其工作的環境條件，因為電動閥門中的電動裝置是一機電設備，其工作情況受其工作環境影響很大。 通常情況下，電動閥門所處工作環境有以下幾種：

    1、室內安裝或有防護措(cuo)施戶(hu)外(wai)使用；

 ;   2、戶(hu)外(wai)露天安(an)裝，有風、砂、雨露、陽(yang)光等(deng)侵蝕(shi)；

    3、具有易燃、易爆氣體或粉(fen)塵(chen)環境；

    4、濕熱(re)帶、干熱(re)帶地區環境；

    5、管(guan)道介質溫(wen)度(du)高達(da)480℃以上；

    6、環(huan)境溫度低(di)于(yu)-20℃以下；

    7、易遭水(shui)淹或(huo)浸水(shui)中；

    8、具有(you)放射(she)性(xing)物質(zhi)（核電站及(ji)放射(she)性(xing)物質(zhi)試驗(yan)裝置）環境(jing)；

    9、艦船上或船塢碼頭(tou)（有鹽霧、霉菌(jun)、潮濕）的環境(jing)；

    10、具(ju)有劇烈(lie)振動(dong)的場合；

    11、易于發生火災(zai)的場合(he)； 

對(dui)于上(shang)述環境中的(de)(de)電(dian)(dian)動(dong)(dong)(dong)閥(fa)(fa)(fa)門，其(qi)電(dian)(dian)動(dong)(dong)(dong)裝置(zhi)(zhi)結構、材(cai)料和防護措施皆不(bu)(bu)同(tong)。因此，應依據上(shang)述工作環境選擇(ze)相應的(de)(de)閥(fa)(fa)(fa)門電(dian)(dian)動(dong)(dong)(dong)裝置(zhi)(zhi)。根(gen)據工程(cheng)控制要(yao)求，對(dui)電(dian)(dian)動(dong)(dong)(dong)閥(fa)(fa)(fa)門來講，其(qi)控制功(gong)能(neng)是由(you)電(dian)(dian)動(dong)(dong)(dong)裝置(zhi)(zhi)來完成的(de)(de)。使(shi)用電(dian)(dian)動(dong)(dong)(dong)閥(fa)(fa)(fa)門的(de)(de)目的(de)(de)，就是對(dui)閥(fa)(fa)(fa)門的(de)(de)開、閉以(yi)及調(diao)節聯動(dong)(dong)(dong)實現(xian)非人工的(de)(de)電(dian)(dian)氣(qi)控制或計算機 控制。目前的(de)(de)電(dian)(dian)動(dong)(dong)(dong)裝置(zhi)(zhi)使(shi)用已不(bu)(bu)只是為了節省人力(li)了。由(you)于不(bu)(bu)同(tong)廠(chang)家產品的(de)(de)功(gong)能(neng)和質量差異較大，因此，選擇(ze)電(dian)(dian)動(dong)(dong)(dong)裝置(zhi)(zhi)和選擇(ze)所配閥(fa)(fa)(fa)門對(dui)工程(cheng)同(tong)等重要(yao)。

由(you)于工業自動(dong)(dong)化水(shui)平的(de)要求(qiu)不(bu)斷提高，一(yi)(yi)方(fang)(fang)面對電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)的(de)使用(yong)(yong)量(liang)越(yue)來越(yue)多，另(ling)一(yi)(yi)方(fang)(fang)面對電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)要求(qiu)也越(yue)來越(yue)高，越(yue)來越(yue)復雜。所(suo)以電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)在電(dian)(dian)(dian)(dian)(dian)氣(qi)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang) 面的(de)設(she)計也在不(bu)斷更新。隨著(zhu)科學技術(shu)的(de)進(jin)步及(ji)計算機(ji)的(de)普(pu)及(ji)應(ying)用(yong)(yong)，新型的(de)、多樣的(de)電(dian)(dian)(dian)(dian)(dian)氣(qi)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang)式(shi)(shi)將不(bu)斷地出現(xian)。對電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)總體控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang)面的(de)考慮(lv)，應(ying)注(zhu)意選擇電(dian)(dian)(dian)(dian)(dian)動(dong)(dong) 閥門(men)(men)的(de)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang)式(shi)(shi)。例如，根據工程(cheng)(cheng)需(xu)(xu)要，是(shi)否(fou)使用(yong)(yong)集中控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang)式(shi)(shi)，還是(shi)單(dan)臺(tai)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)方(fang)(fang)式(shi)(shi)，是(shi)否(fou)與(yu)其他設(she)備聯動(dong)(dong)，程(cheng)(cheng)序(xu)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)還是(shi)應(ying)用(yong)(yong)計算機(ji)程(cheng)(cheng)序(xu)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)等(deng)等(deng)，其控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)原理都 不(bu)一(yi)(yi)樣。閥門(men)(men)電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)裝(zhuang)置(zhi)廠家(jia)樣本(ben)給出的(de)僅是(shi)標準電(dian)(dian)(dian)(dian)(dian)氣(qi)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)原理，因此(ci)使用(yong)(yong)部門(men)(men)應(ying)與(yu)電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)裝(zhuang)置(zhi)生產廠進(jin)行技術(shu)交(jiao)底，明確技術(shu)要求(qiu)。 此(ci)外，在選擇電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)時，應(ying)考慮(lv)是(shi)否(fou)附加購置(zhi)電(dian)(dian)(dian)(dian)(dian)動(dong)(dong)閥門(men)(men)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)器(qi)(qi)。因為(wei)一(yi)(yi)般情況，控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)器(qi)(qi)是(shi)需(xu)(xu)要單(dan)獨購買(mai)的(de)。多數情況下，采(cai)用(yong)(yong)單(dan)臺(tai)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)時，是(shi)需(xu)(xu)要購買(mai)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)器(qi)(qi)的(de)， 因為(wei)購買(mai)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)器(qi)(qi)比(bi)用(yong)(yong)戶自行設(she)計、制(zhi)(zhi)造要方(fang)(fang)便、便宜。當電(dian)(dian)(dian)(dian)(dian)氣(qi)控(kong)(kong)(kong)(kong)(kong)制(zhi)(zhi)性能滿(man)足不(bu)了工程(cheng)(cheng)設(she)計要求(qiu)時，應(ying)向生產廠提出修改(gai)或重新設(she)計。

閥(fa)門(men)電(dian)(dian)(dian)(dian)動裝置(zhi)(zhi)是實(shi)現閥(fa)門(men)程(cheng)控(kong)(kong)、自控(kong)(kong)和(he)遙控(kong)(kong)不可(ke)缺少的(de)設(she)備(bei)，其(qi)運動過程(cheng)可(ke)由(you)行程(cheng)、轉(zhuan)矩或(huo)軸(zhou)向推(tui)力(li)的(de)大小來控(kong)(kong)制。由(you)于閥(fa)門(men)電(dian)(dian)(dian)(dian)動裝置(zhi)(zhi)的(de)工(gong)作(zuo)特(te)性和(he)利用率取決于閥(fa)門(men)的(de)種(zhong)類、裝置(zhi)(zhi)工(gong)作(zuo)規范及閥(fa)門(men)在管線(xian)或(huo)設(she)備(bei)上的(de)位(wei)置(zhi)(zhi)，因此，正確選(xuan)擇閥(fa)門(men)電(dian)(dian)(dian)(dian)動裝置(zhi)(zhi)，對防止出現超負荷(he)現象(工(gong)作(zuo)轉(zhuan)矩高于控(kong)(kong)制轉(zhuan)矩)至關重要。通常，正確選(xuan)擇閥(fa)門(men)電(dian)(dian)(dian)(dian)動裝置(zhi)(zhi)的(de)依據如下(xia)：

操(cao)(cao)作(zuo)力(li)矩操(cao)(cao)作(zuo)力(li)矩是選擇閥門(men)(men)電動(dong)裝(zhuang)置的最主要參數(shu)，電動(dong)裝(zhuang)置輸出力(li)矩應為閥門(men)(men)操(cao)(cao)作(zuo)最大(da)力(li)矩的1.2～1.5倍。

操作(zuo)推力(li)(li)(li)閥(fa)門電動裝(zhuang)置的主機(ji)結構(gou)有兩種：一種是不配置推力(li)(li)(li)盤(pan)(pan)，直(zhi)接輸出(chu)力(li)(li)(li)矩(ju)；另一種是配置推力(li)(li)(li)盤(pan)(pan)，輸出(chu)力(li)(li)(li)矩(ju)通過推力(li)(li)(li)盤(pan)(pan)中的閥(fa)桿螺母轉換為(wei)輸出(chu)推力(li)(li)(li)。

輸出(chu)軸轉(zhuan)動(dong)圈數(shu)(shu)閥(fa)門電動(dong)裝置(zhi)輸出(chu)軸轉(zhuan)動(dong)圈數(shu)(shu)的多少與閥(fa)門的公稱通徑、閥(fa)桿螺(luo)(luo)(luo)距、螺(luo)(luo)(luo)紋(wen)(wen)(wen)頭(tou)數(shu)(shu)有關，要按M＝H／ZS計算(M為(wei)(wei)電動(dong)裝置(zhi)應滿足的總轉(zhuan)動(dong)圈數(shu)(shu)，H為(wei)(wei)閥(fa)門開啟高(gao)度(du)，S為(wei)(wei)閥(fa)桿傳(chuan)動(dong)螺(luo)(luo)(luo)紋(wen)(wen)(wen)螺(luo)(luo)(luo)距，Z為(wei)(wei)閥(fa)桿螺(luo)(luo)(luo)紋(wen)(wen)(wen)頭(tou)數(shu)(shu))。

閥桿直徑對多回轉類明桿閥門，如果電動裝置允許通過的最大閥桿直徑不能通過所配閥門的閥桿，便不能組裝成電動閥門。因此，電動裝置空心輸出軸的內徑必須大于明桿閥門的閥桿外徑。對部分回轉閥門以及多回轉閥門中的暗桿閥門，雖不用考慮閥桿直徑的通過問題，但在選配時亦應充分考慮閥桿直徑與鍵槽的尺寸，使組裝后能正常工作。

輸出轉(zhuan)速閥門(men)的(de)(de)啟閉速度若過(guo)快，易產生水擊現象。因此，應根據不同(tong)使用條(tiao)件，選(xuan)擇恰(qia)當(dang)的(de)(de)啟閉速度。

閥門(men)電(dian)動(dong)裝(zhuang)(zhuang)置(zhi)有其(qi)特殊(shu)要求，即必(bi)須能夠限(xian)定(ding)(ding)轉(zhuan)(zhuan)(zhuan)矩(ju)或軸(zhou)向(xiang)力。通(tong)常閥門(men)電(dian)動(dong)裝(zhuang)(zhuang)置(zhi)采用限(xian)制(zhi)轉(zhuan)(zhuan)(zhuan)矩(ju)的(de)(de)連(lian)軸(zhou)器。當(dang)電(dian)動(dong)裝(zhuang)(zhuang)置(zhi)規(gui)格確(que)定(ding)(ding)之后，其(qi)控制(zhi)轉(zhuan)(zhuan)(zhuan)矩(ju)也就確(que)定(ding)(ding)了。一(yi)(yi)般在預先確(que)定(ding)(ding)的(de)(de)時間內運行，電(dian)機(ji)(ji)不會超(chao)負荷(he)。但如出現(xian)下列情況便可能導致(zhi)超(chao)負荷(he)：一(yi)(yi)是(shi)(shi)電(dian)源電(dian)壓低，得不到所需的(de)(de)轉(zhuan)(zhuan)(zhuan)矩(ju)，使(shi)(shi)電(dian)機(ji)(ji)停(ting)止轉(zhuan)(zhuan)(zhuan)動(dong)；二是(shi)(shi)錯誤地調定(ding)(ding)轉(zhuan)(zhuan)(zhuan)矩(ju)限(xian)制(zhi)機(ji)(ji)構(gou)(gou)，使(shi)(shi)其(qi)大于停(ting)止的(de)(de)轉(zhuan)(zhuan)(zhuan)矩(ju)，造(zao)成連(lian)續(xu)產(chan)生(sheng)過(guo)大轉(zhuan)(zhuan)(zhuan)矩(ju)，使(shi)(shi)電(dian)機(ji)(ji)停(ting)止轉(zhuan)(zhuan)(zhuan)動(dong)；三是(shi)(shi)斷續(xu)使(shi)(shi)用，產(chan)生(sheng)的(de)(de)熱(re)量積蓄，超(chao)過(guo)了電(dian)機(ji)(ji)的(de)(de)允(yun)許溫(wen)(wen)升值；四是(shi)(shi)因(yin)某種原因(yin)轉(zhuan)(zhuan)(zhuan)矩(ju)限(xian)制(zhi)機(ji)(ji)構(gou)(gou)電(dian)路發(fa)生(sheng)故(gu)障，使(shi)(shi)轉(zhuan)(zhuan)(zhuan)矩(ju)過(guo)大；五是(shi)(shi)使(shi)(shi)用環(huan)境溫(wen)(wen)度過(guo)高，相對使(shi)(shi)電(dian)機(ji)(ji)熱(re)容量下降。

過去對(dui)電(dian)機(ji)進(jin)行(xing)保護(hu)的(de)辦(ban)法(fa)是(shi)(shi)使用熔斷(duan)器、過流繼(ji)電(dian)器、熱(re)繼(ji)電(dian)器、恒溫(wen)器等，但這些辦(ban)法(fa)各(ge)有利弊。對(dui)電(dian)動裝置這種變(bian)負荷設備，絕對(dui)可靠的(de)保護(hu)辦(ban)法(fa)是(shi)(shi)沒有的(de)。因此，必須采取各(ge)種組(zu)合(he)方式(shi)，歸納起來有兩種：一(yi)是(shi)(shi)對(dui)電(dian)機(ji)輸入(ru)電(dian)流的(de)增(zeng)減進(jin)行(xing)判斷(duan)；二(er)是(shi)(shi)對(dui)電(dian)機(ji)本(ben)身(shen)發熱(re)情況進(jin)行(xing)判斷(duan)。這兩種方式(shi)，無論那種都要考慮電(dian)機(ji)熱(re)容量給定的(de)時間余量。

通(tong)常(chang)，過(guo)負荷的基本保護方法是：對電(dian)機連續運轉或點(dian)動操作的過(guo)負荷保護，采(cai)(cai)用(yong)(yong)恒溫器(qi)(qi)；對電(dian)機堵(du)轉的保護，采(cai)(cai)用(yong)(yong)熱(re)繼(ji)(ji)電(dian)器(qi)(qi)；對短路事故，采(cai)(cai)用(yong)(yong)熔斷(duan)器(qi)(qi)或過(guo)流繼(ji)(ji)電(dian)器(qi)(qi)。