實驗室通(tong)(tong)(tong)風(feng)(feng)系統(tong)工(gong)程是密閉罩(zhao)的(de)一種特(te)別方式,產生(sheng)有(you)(you)害(hai)物的(de)操作過(guo)程徹底(di)在罩(zhao)內進(jin)行(xing),通(tong)(tong)(tong)風(feng)(feng)柜(ju)上通(tong)(tong)(tong)常設有(you)(you)可開閉的(de)操作孔和調查孔,為了避免由于通(tong)(tong)(tong)風(feng)(feng)柜(ju)內機械設備的(de)擾動、化(hua)學反應或許熱源的(de)熱壓等原因導(dao)致的(de)有(you)(you)害(hai)物逸出,有(you)(you)必要對通(tong)(tong)(tong)風(feng)(feng)柜(ju)進(jin)行(xing)抽風(feng)(feng),使柜(ju)內形成負壓。通(tong)(tong)(tong)風(feng)(feng)柜(ju)的(de)抽風(feng)(feng)方式許多(duo),通(tong)(tong)(tong)常運用的(de)有(you)(you):

　　(1)上部排(pai)風(feng)(feng)(feng)的通風(feng)(feng)(feng)柜。當通風(feng)(feng)(feng)柜內(nei)產生的有害氣體密度比空氣小,或當通風(feng)(feng)(feng)柜內(nei)有發熱體時,為有效(xiao)地避(bi)免有害氣體從操作口上緣逸出,應(ying)挑(tiao)選上部排(pai)風(feng)(feng)(feng)的通風(feng)(feng)(feng)柜。這類通風(feng)(feng)(feng)柜構(gou)造簡略,運(yun)用(yong)廣(guang)泛。

　　(2)上(shang)下聯(lian)合排風的(de)通(tong)風柜(ju)。當通(tong)風柜(ju)內既有(you)發(fa)熱體,一起又產生密度大(da)小(xiao)不等的(de)有(you)害氣體時(shi),為(wei)有(you)效地習(xi)慣各種(zhong)(zhong)不一樣操作條件的(de)變化,最佳挑選上(shang)下聯(lian)合排風的(de)通(tong)風柜(ju)。這種(zhong)(zhong)通(tong)風柜(ju)運(yun)用(yong)靈敏,但構造比較復雜。

　　(3)下部排(pai)(pai)風(feng)的通(tong)風(feng)柜。當通(tong)風(feng)柜內沒有(you)發(fa)熱(re)體,且產生(sheng)的有(you)害氣體密度比空氣大,柜內氣流降低,為有(you)效地避免有(you)害氣體從操作(zuo)口下緣逸出(chu),應(ying)挑選下部排(pai)(pai)風(feng)的通(tong)風(feng)柜。這類通(tong)風(feng)柜的排(pai)(pai)風(feng)條縫口緊靠操作(zuo)臺面,或間隔(ge)操作(zuo)臺面有(you)必(bi)定(ding)的高度

　　(4)供(gong)(gong)氣(qi)式(shi)(shi)通風柜(ju)(ju)。供(gong)(gong)氣(qi)式(shi)(shi)通風柜(ju)(ju)其排風量(liang)的1/4～1/3為室(shi)(shi)內(nei)空氣(qi),2/3～3/4為輔(fu)佐(zuo)供(gong)(gong)應的空氣(qi)。供(gong)(gong)氣(qi)式(shi)(shi)通風柜(ju)(ju)可(ke)削減從室(shi)(shi)內(nei)的排風量(liang),有利于確保室(shi)(shi)內(nei)的潔凈度和正壓,在供(gong)(gong)溫(wen)暖空調房間內(nei)運(yun)用(yong)時,能(neng)(neng)節約(yue)耗熱量(liang)和耗冷量(liang),所以,也稱節能(neng)(neng)型通風柜(ju)(ju)

　　實驗室(shi)通風柜的排風體系和安(an)置：

　　(1)通風(feng)柜(ju)、通風(feng)機(ji)及排風(feng)管應(ying)挑選(xuan)有防腐蝕功(gong)(gong)用和防爆(bao)功(gong)(gong)能的資料和設備

　　(2)通風柜的(de)排(pai)風體(ti)系宜選用(yong)機械排(pai)風,自然排(pai)風易受外界氣候(hou)要素的(de)影響,通常不宜選用(yong)。

　　(3)通(tong)風柜(ju)通(tong)常(chang)應設置(zhi)在實驗室受攪擾起碼的當地,遠離(li)開著的門窗(chuang)和來往(wang)頻(pin)繁的通(tong)道和送風口

　　(4)通風柜的排(pai)(pai)風出(chu)口,不管其(qi)體(ti)系為(wei)獨自排(pai)(pai)風或集中排(pai)(pai)風,均應裝設有(you)一個可封閉的閥門(men),以避(bi)免(mian)氣體(ti)倒灌和(he)相互串通。

　　(5)通(tong)(tong)(tong)風(feng)(feng)柜(ju)(ju)可設獨自排(pai)風(feng)(feng)體(ti)(ti)系(xi)(xi)或數個以上集中排(pai)風(feng)(feng)體(ti)(ti)系(xi)(xi)。當選(xuan)用(yong)集中式排(pai)風(feng)(feng)體(ti)(ti)系(xi)(xi)時,通(tong)(tong)(tong)常(chang)每個體(ti)(ti)系(xi)(xi)所帶的(de)通(tong)(tong)(tong)風(feng)(feng)柜(ju)(ju)不(bu)宜(yi)多于3～4個。一(yi)起在體(ti)(ti)系(xi)(xi)區分上,應根(gen)據有害物質性質的(de)不(bu)一(yi)樣分隔設置。如(ru)強(qiang)腐蝕(shi)的(de)氣(qi)體(ti)(ti)與通(tong)(tong)(tong)常(chang)性腐蝕(shi)氣(qi)體(ti)(ti)的(de)排(pai)風(feng)(feng)應予以分隔。