實驗室(shi)通風(feng)設(she)計采(cai)用以(yi)下步(bu)驟和(he)方案：

　　(1)實驗(yan)(yan)室根(gen)據(ju)工藝要(yao)求(qiu)和功能布置選擇一定數(shu)量(liang)的通(tong)風(feng)(feng)柜(ju)，有的還兼有部(bu)分局(ju)部(bu)排風(feng)(feng)罩。通(tong)常(chang)校(xiao)核下來換氣次(ci)數(shu)遠遠大于(yu)10次(ci)，一般在(zai)20-30次(ci)以上，滿足換氣次(ci)數(shu)要(yao)求(qiu)。但(dan)是(shi)此(ci)換氣次(ci)數(shu)是(shi)按照通(tong)風(feng)(feng)柜(ju)最大開(kai)啟(qi)面積計算的通(tong)風(feng)(feng)量(liang)，資(zi)料和經(jing)驗(yan)(yan)表明100臺通(tong)風(feng)(feng)柜(ju)99%的時間只有18個或更(geng)少(shao)的人在(zai)使用。故還應校(xiao)核通(tong)風(feng)(feng)柜(ju)最小(xiao)開(kai)啟(qi)面積時的通(tong)風(feng)(feng)量(liang)和換氣次(ci)數(shu)，若(ruo)小(xiao)于(yu)換氣次(ci)數(shu)要(yao)求(qiu)，則增加(jia)綜合排風(feng)(feng)系統(tong)。

　　(2)實(shi)驗室通(tong)風(feng)采用(yong)全新(xin)風(feng)系統，通(tong)風(feng)柜(ju)的(de)(de)(de)排氣不在室內(nei)循(xun)環。由于實(shi)驗室要(yao)求房(fang)間(jian)(jian)相對其(qi)他輔助(zhu)區域為負壓。所以實(shi)驗室的(de)(de)(de)新(xin)風(feng)量(liang)設計為排風(feng)量(liang)的(de)(de)(de)70﹪-80﹪。另(ling)外20﹪-30﹪的(de)(de)(de)新(xin)風(feng)送至實(shi)驗室輔助(zhu)房(fang)間(jian)(jian)、辦公、管理用(yong)房(fang)、內(nei)走道等(deng)，再由門窗(chuang)縫隙補充(chong)到房(fang)間(jian)(jian)。

　　(3)通風柜的(de)風量平衡可以(yi)采用(yong)定風量控制系(xi)統，即排風量恒(heng)定，送風量和(he)門(men)窗縫(feng)隙(xi)補充風量恒(heng)定。實(shi)驗(yan)室(shi)家(jia)具此方(fang)法適(shi)用(yong)于最大排風量滿足最小換氣次數要(yao)求(qiu)的(de)實(shi)驗(yan)室(shi)。

　　(4)對(dui)于排風(feng)(feng)(feng)(feng)(feng)量遠大于最(zui)小通(tong)風(feng)(feng)(feng)(feng)(feng)量要求(qiu)(qiu)的(de)(de)房間還可以采(cai)用(yong)兩段式通(tong)風(feng)(feng)(feng)(feng)(feng)控(kong)制(zhi)系(xi)統(tong)(tong)保證風(feng)(feng)(feng)(feng)(feng)量平衡(heng)，即根據通(tong)風(feng)(feng)(feng)(feng)(feng)柜的(de)(de)位移信號，排風(feng)(feng)(feng)(feng)(feng)機、送風(feng)(feng)(feng)(feng)(feng)機有2種送風(feng)(feng)(feng)(feng)(feng)工況，低(di)風(feng)(feng)(feng)(feng)(feng)量工況應(ying)用(yong)于維持最(zui)小換氣(qi)次數的(de)(de)要求(qiu)(qiu)，節約能耗。此(ci)情形藥(yao)檢所采(cai)用(yong)了變風(feng)(feng)(feng)(feng)(feng)量控(kong)制(zhi)系(xi)統(tong)(tong)。通(tong)風(feng)(feng)(feng)(feng)(feng)柜風(feng)(feng)(feng)(feng)(feng)量變化(hua)時，排風(feng)(feng)(feng)(feng)(feng)量也會相對(dui)變小，此(ci)時要求(qiu)(qiu)放置在(zai)屋頂的(de)(de)排風(feng)(feng)(feng)(feng)(feng)機隨著(zhu)通(tong)風(feng)(feng)(feng)(feng)(feng)柜柜門的(de)(de)位置變化(hua)而變頻，降(jiang)低(di)風(feng)(feng)(feng)(feng)(feng)量，保證通(tong)風(feng)(feng)(feng)(feng)(feng)柜面風(feng)(feng)(feng)(feng)(feng)速(su)恒定。同時自控(kong)系(xi)統(tong)(tong)改變全新風(feng)(feng)(feng)(feng)(feng)風(feng)(feng)(feng)(feng)(feng)機的(de)(de)頻率，降(jiang)低(di)風(feng)(feng)(feng)(feng)(feng)量，維持負壓平衡(heng)。變風(feng)(feng)(feng)(feng)(feng)量系(xi)統(tong)(tong)可以降(jiang)低(di)系(xi)統(tong)(tong)能耗。系(xi)統(tong)(tong)最(zui)大、最(zui)小換氣(qi)次數接近則考(kao)慮采(cai)用(yong)定風(feng)(feng)(feng)(feng)(feng)量系(xi)統(tong)(tong)，使得系(xi)統(tong)(tong)簡單，降(jiang)低(di)初投資。

　　通(tong)(tong)風系(xi)(xi)統(tong)(tong)(tong)除上文所述對(dui)通(tong)(tong)風柜有(you)特殊要求(qiu)外，對(dui)其他設備和(he)控(kong)(kong)制系(xi)(xi)統(tong)(tong)(tong)也有(you)一定(ding)(ding)的(de)(de)(de)要求(qiu)和(he)標準。通(tong)(tong)風柜的(de)(de)(de)選擇除滿(man)足(zu)排風和(he)捕(bu)捉(zhuo)(zhuo)能力(li)外，還(huan)要注意需(xu)要根據調(diao)節門移(yi)動而立即改變風量，實(shi)驗室(shi)設備廠家維持(chi)表(biao)面(mian)風速(su)的(de)(de)(de)恒定(ding)(ding)。筆者(zhe)建(jian)議系(xi)(xi)統(tong)(tong)(tong)風量的(de)(de)(de)測(ce)定(ding)(ding)和(he)控(kong)(kong)制以(yi)柜門位移(yi)為信號(hao)而不是(shi)測(ce)定(ding)(ding)表(biao)面(mian)風速(su)來測(ce)定(ding)(ding)。實(shi)驗室(shi)壓力(li)控(kong)(kong)制和(he)最小通(tong)(tong)風量的(de)(de)(de)控(kong)(kong)制除了設備選型因(yin)素以(yi)外，通(tong)(tong)風系(xi)(xi)統(tong)(tong)(tong)設計和(he)控(kong)(kong)制系(xi)(xi)統(tong)(tong)(tong)是(shi)關鍵因(yin)素，要保證系(xi)(xi)統(tong)(tong)(tong)的(de)(de)(de)反應(ying)時(shi)間要足(zu)夠短(<1秒)，通(tong)(tong)風系(xi)(xi)統(tong)(tong)(tong)不平衡會導致通(tong)(tong)風柜排風和(he)捕(bu)捉(zhuo)(zhuo)能力(li)散失，氣(qi)流流出實(shi)驗室(shi)，建(jian)筑物內壓力(li)不穩定(ding)(ding)。實(shi)驗室(shi)氣(qi)路系(xi)(xi)統(tong)(tong)(tong)

　　還有一(yi)點要注意的(de)(de)(de)是(shi)系(xi)(xi)統(tong)(tong)應(ying)該是(shi)壓力變(bian)化(hua)(hua)(hua)無關型的(de)(de)(de)，即系(xi)(xi)統(tong)(tong)風(feng)量(liang)的(de)(de)(de)變(bian)化(hua)(hua)(hua)不會(hui)(hui)因為風(feng)管內(nei)靜壓的(de)(de)(de)變(bian)化(hua)(hua)(hua)而(er)使得反應(ying)時間緩慢影響(xiang)系(xi)(xi)統(tong)(tong)流(liu)(liu)量(liang)的(de)(de)(de)精(jing)確(que)性。壓力相關型的(de)(de)(de)系(xi)(xi)統(tong)(tong)也會(hui)(hui)造(zao)成(cheng)系(xi)(xi)統(tong)(tong)流(liu)(liu)量(liang)設(she)備無法精(jing)確(que)控制，緩慢的(de)(de)(de)反應(ying)時間會(hui)(hui)讓送(song)排風(feng)設(she)備產(chan)生震(zhen)蕩，速度不穩定(ding)會(hui)(hui)有大量(liang)的(de)(de)(de)平衡問題存在，波動的(de)(de)(de)送(song)、排風(feng)系(xi)(xi)統(tong)(tong)使氣(qi)流(liu)(liu)平衡復雜化(hua)(hua)(hua)，從而(er)自(zi)控系(xi)(xi)統(tong)(tong)無法實(shi)現調節功能。

　　所以(yi)(yi)，系(xi)統首(shou)先監測(ce)的(de)(de)是通風(feng)(feng)(feng)柜的(de)(de)狀態，接受調(diao)(diao)節門(men)(men)感應(ying)器信(xin)號后可以(yi)(yi)計算調(diao)(diao)節門(men)(men)面積(風(feng)(feng)(feng)量)，此(ci)時向(壓力(li)無關型)閥門(men)(men)送(song)出(chu)風(feng)(feng)(feng)量控(kong)制信(xin)號，調(diao)(diao)節閥門(men)(men)的(de)(de)開度，送(song)風(feng)(feng)(feng)量跟隨排(pai)風(feng)(feng)(feng)量即刻變化，送(song)排(pai)風(feng)(feng)(feng)機變頻調(diao)(diao)節送(song)風(feng)(feng)(feng)量。

　　由于實驗(yan)室氣(qi)(qi)體排放中存在(zai)(zai)著很多有(you)毒(du)和(he)(he)酸(suan)(suan)堿腐蝕(shi)性極強(qiang)的(de)氣(qi)(qi)體，所以在(zai)(zai)排入大氣(qi)(qi)前要對氣(qi)(qi)體進(jin)行(xing)過濾處(chu)理，通常情(qing)況(kuang)下：酸(suan)(suan)性氣(qi)(qi)體選用立(li)式酸(suan)(suan)霧(wu)塔;有(you)毒(du)和(he)(he)有(you)機氣(qi)(qi)體選用光學催(cui)(cui)化(hua)凈化(hua)箱。兩種設備分(fen)別安裝(zhuang)(zhuang)在(zai)(zai)排風(feng)系(xi)統末端，立(li)式酸(suan)(suan)霧(wu)塔安裝(zhuang)(zhuang)在(zai)(zai)風(feng)機的(de)正壓(ya)段(duan)(duan)，光學催(cui)(cui)化(hua)凈化(hua)箱安裝(zhuang)(zhuang)在(zai)(zai)風(feng)機負壓(ya)段(duan)(duan)。動(dong)物房的(de)氣(qi)(qi)體經過初效和(he)(he)中效過濾后，直(zhi)接排入大氣(qi)(qi)，但在(zai)(zai)排風(feng)口處(chu)做高壓(ya)噴射流處(chu)理，噴射高度(du)在(zai)(zai)3米以上。