測量氣體成分的流程分析儀表。在很多生產過程中，特別是在存在化學反應的生產過程中
，僅僅根據溫度

、壓力、流量等物理參數進行自動控製常常是不夠的。例如，在合成氨生產中
，僅控製合成塔的溫度、壓力、liuliangbingbunengbaozhengzuigaodehechenglv，bixutongshifenxijinqidehuaxuechengfen，kongzhiqingqihedanqidezuijiabili，cainenghuodejiaogaodeshengchanlv。youruzaiguoluderanshaokongzhizhongchuxukongzhiranliaoyuzhurankongqidebiliwai，haibixuzaixianfenxiyandaodehuaxuechengfen，jucigaibianzhurankongqidegonggeiliang
，shiluzihuodezuigaoderexiaolv。ciwai，zaipaichuyouhaiqitidegongchangzhong

，yebixucaiyongqitifenxiyiduiyouhaiqitijinxinglianxujianshi，yifangzhiweihaigongrenjiankanghuowuranhuanjinghuoyinqibaozhadengexingshigu。youyubeifenxiqitideqianchawanbiehefenxiyuanlideduozhongduoyang
，qitifenxiyidezhongleifanduo。changyongdeyouredaoshiqitifenxiyi、電化學式氣體分析儀和紅外線吸收式分析儀等。

1
、熱導式氣體分析儀
　　yizhongwulileideqitifenxiyibiao。tagenjubutongqitijuyoubutongrechuandaonenglideyuanli，tongguocedinghunheqitidaorexishulaituisuanqizhongmouxiezufendehanliang。zhezhongfenxiyibiaojiandankekao,適用的氣體種類較多,shiyizhongjibendefenxiyibiao。danzhijieceliangqitidedaorexishubijiaokunnan，suoyishijishangchangbaqitidaorexishudebianhuazhuanhuanweidianzudebianhua，zaiyongdianqiaolaiceding。redaoshiqitifenxiyidereminyuanjianzhuyaoyoubandaotiminganyuanjianhejinshudianzusilianglei。bandaotiminganyuanjiantijixiao

、熱慣性小
，電阻溫度係數大,所以靈敏度高,時間滯後小。在鉑線圈上燒結珠形金屬氧化物作為敏感元件，再在內電阻
、發熱量均相等的同樣鉑線圈上繞結對氣體無反應的材料作為補償用元件（圖1）。這(zhe)兩(liang)種(zhong)元(yuan)件(jian)作(zuo)為(wei)兩(liang)臂(bi)構(gou)成(cheng)電(dian)橋(qiao)電(dian)路(lu)，即(ji)是(shi)測(ce)量(liang)回(hui)路(lu)。半(ban)導(dao)體(ti)金(jin)屬(shu)氧(yang)化(hua)物(wu)敏(min)感(gan)元(yuan)件(jian)吸(xi)附(fu)被(bei)測(ce)氣(qi)體(ti)時(shi)，電(dian)導(dao)率(lv)和(he)熱(re)導(dao)率(lv)即(ji)發(fa)生(sheng)變(bian)化(hua)，元(yuan)件(jian)的(de)散(san)熱(re)狀(zhuang)態(tai)也(ye)隨(sui)之(zhi)變(bian)化(hua)。元(yuan)件(jian)溫(wen)度(du)變(bian)化(hua)使(shi)鉑(bo)線(xian)圈(quan)的(de)電(dian)阻(zu)變(bian)化(hua)
，電(dian)橋(qiao)遂(sui)有(you)一(yi)不(bu)平(ping)衡(heng)電(dian)壓(ya)輸(shu)出(chu)，據(ju)此(ci)可(ke)檢(jian)測(ce)氣(qi)體(ti)的(de)濃(nong)度(du)。熱(re)導(dao)式(shi)氣(qi)體(ti)分(fen)析(xi)儀(yi)的(de)應(ying)用(yong)範(fan)圍(wei)很(hen)廣(guang)
，除(chu)通(tong)常(chang)用(yong)來(lai)分(fen)析(xi)氫(qing)氣(qi)、氨氣
、二氧化碳、二氧化硫和低濃度可燃性氣體含量外
，還可作為色譜分析儀中的檢測器用以分析其他成分。

2、電化學式氣體分析儀
　　yizhonghuaxueleideqitifenxiyibiao。tagenjuhuaxuefanyingsuoyinqideliziliangdebianhuahuodianliubianhualaiceliangqitichengfen。weiletigaoxuanzexing
，fangzhiceliangdianjibiaomianzhanwuhebaochidianjieyexingneng

，yibancaiyonggemojiegou。changyongdedianhuaxueshifenxiyiyoudingdianweidianjieshihejiafanidianchishiliangzhong。dingdianweidianjieshifenxiyi（圖2）的de工gong作zuo原yuan理li是shi在zai電dian極ji上shang施shi加jia特te定ding電dian位wei，被bei測ce氣qi體ti在zai電dian極ji表biao麵mian就jiu產chan生sheng電dian解jie作zuo用yong，隻zhi要yao測ce量liang加jia在zai電dian極ji上shang的de電dian位wei，即ji可ke確que定ding被bei測ce氣qi體ti特te有you的de電dian解jie電dian位wei
，從cong而er使shi儀yi表biao具ju有you選xuan擇ze識shi別bie被bei測ce氣qi體ti的de能neng力li。伽jia伐fa尼ni電dian池chi式shi分fen析xi儀yi（圖3）shijiangtouguogemoerkuosandaodianjieyezhongdebeiceqitidianjie
，celiangsuoxingchengdedianjiedianliu，jiunengquedingbeiceqitidenongdu。tongguoxuanzebutongdedianjicailiaohedianjieyelaigaibiandianjibiaomiandeneibudianyacongershixianduijuyoubutongdianjiedianweideqitidexuanzexing。

 3

、紅外線吸收式分析儀
　　根據不同組分氣體對不同波長的紅外線具有選擇性吸收的特性而工作的分析儀表。測量這種吸收光譜可判別出氣體的種類；測(ce)量(liang)吸(xi)收(shou)強(qiang)度(du)可(ke)確(que)定(ding)被(bei)測(ce)氣(qi)體(ti)的(de)濃(nong)度(du)。紅(hong)外(wai)線(xian)分(fen)析(xi)儀(yi)的(de)使(shi)用(yong)範(fan)圍(wei)寬(kuan)，不(bu)僅(jin)可(ke)分(fen)析(xi)氣(qi)體(ti)成(cheng)分(fen)，也(ye)可(ke)分(fen)析(xi)溶(rong)液(ye)成(cheng)分(fen)，且(qie)靈(ling)敏(min)度(du)較(jiao)高(gao)
，反(fan)應(ying)迅(xun)速(su),能在線連續指示,也可組成調節係統。工業上常用的紅外線氣體分析儀的檢測部分由兩個並列的結構相同的光學係統組成。
　　一yi個ge是shi測ce量liang室shi，一yi個ge是shi參can比bi室shi。兩liang室shi通tong過guo切qie光guang板ban以yi一yi定ding周zhou期qi同tong時shi或huo交jiao替ti開kai閉bi光guang路lu。在zai測ce量liang室shi中zhong導dao入ru被bei測ce氣qi體ti後hou
，具ju有you被bei測ce氣qi體ti特te有you波bo長chang的de光guang被bei吸xi收shou，從cong而er使shi透tou過guo測ce量liang室shi這zhe一yi光guang路lu而er進jin入ru紅hong外wai線xian接jie收shou氣qi室shi的de光guang通tong量liang減jian少shao。氣qi體ti濃nong度du越yue高gao，進jin入ru到dao紅hong外wai線xian接jie收shou氣qi室shi的de光guang通tong量liang就jiu越yue少shao
；而er透tou過guo參can比bi室shi的de光guang通tong量liang是shi一yi定ding的de

，進jin入ru到dao紅hong外wai線xian接jie收shou氣qi室shi的de光guang通tong量liang也ye一yi定ding。因yin此ci
，被bei測ce氣qi體ti濃nong度du越yue高gao
，透tou過guo測ce量liang室shi和he參can比bi室shi的de光guang通tong量liang差cha值zhi就jiu越yue大da。這zhe個ge光guang通tong量liang差cha值zhi是shi以yi一yi定ding周zhou期qi振zhen動dong的de振zhen幅fu投tou射she到dao紅hong外wai線xian接jie收shou氣qi室shi的de。接jie收shou氣qi室shi用yong幾ji微wei米mi厚hou的de金jin屬shu薄bo膜mo分fen隔ge為wei兩liang半ban部bu，室shi內nei封feng有you濃nong度du較jiao大da的de被bei測ce組zu分fen氣qi體ti
，在zai吸xi收shou波bo長chang範fan圍wei內nei能neng將jiang射she入ru的de紅hong外wai線xian全quan部bu吸xi收shou，從cong而er使shi脈mai動dong的de光guang通tong量liang變bian為wei溫wen度du的de周zhou期qi變bian化hua，再zai可ke根gen據ju氣qi態tai方fang程cheng使shi溫wen度du的de變bian化hua轉zhuan換huan為wei壓ya力li的de變bian化hua，然ran後hou用yong電dian容rong式shi傳chuan感gan器qi來lai檢jian測ce

，經jing過guo放fang大da處chu理li後hou指zhi示shi出chu被bei測ce氣qi體ti濃nong度du。除chu用yong電dian容rong式shi傳chuan感gan器qi外wai

，也ye可ke用yong直zhi接jie檢jian測ce紅hong外wai線xian的de量liang子zi式shi紅hong外wai線xian傳chuan感gan器qi，並bing采cai用yong紅hong外wai幹gan涉she濾lv光guang片pian進jin行xing波bo長chang選xuan擇ze和he配pei以yi可ke調tiao激ji光guang器qi作zuo光guang源yuan，形xing成cheng一yi種zhong嶄zhan新xin的de全quan固gu體ti式shi紅hong外wai氣qi體ti分fen析xi儀yi。這zhe種zhong分fen析xi儀yi隻zhi用yong一yi個ge光guang源yuan、一個測量室
、yigehongwaixianchuanganqijiunengwanchengqitinongdudeceliang。ciwai，ruocaiyongzhuangyouduogebutongbochangdelvguangpan，zenengtongshifenbiecedingduozufenqitizhongdegezhongqitidenongdu。
　　與紅外線分析儀原理相似的還有紫外線分析儀、光電比色分析儀等
，在工業上也用得較多。