標準氣體貯存容器的穩定性試驗
福州標準氣體dewendingxingshipeizhiheshiyongguochengzhongdeguanjianwenti。zhuangrugaoyagangpingzhongdebiaozhunqitililunshangzaibaocunheshiyongguochengzhongqinongduzhibuyingfashengbianhua。danshijishang,biaozhunqitizhongdezufenqitihuobuchunwuyurongqineibijiechushiwangwangyinqixifu、解吸、化學反應等現象而使其濃度值隨時間發生變化,濃度越低、組成成分越複雜時這種變化越大。因此,標準氣體的穩定性在很大程度上與容器的材料物性、容器內壁的預處理情況和氣體本身的化學特性有著密切的關係。

(1)貯存容器的選擇及預處理
盛裝標準氣體的容器應由耐腐蝕、不生鏽、吸附少、化學性質穩定、機械強度高的材料製成。通常使用的高壓容器是由錳鋼、鉻相鋼、鋁合金或不鏽鋼等材料製成的。通常采用的內壁處理方法有酸洗、水洗、鏡麵研磨、baohechulideng。baohechulishiweilefangzhirongqineibiyinxifuhuojiexidailaideyingxiang,xianduirongqineibijinxingjingmianyan,tushangfangyanghuaqi,ranhoubagaonongduqitichongrenrongqineibingfangzhi10d左右.從而提高標準氣體穩定性的一種方法。飽和處理能大大提高標準氣體定性。
(2)標準氣體穩定性試驗
標biao準zhun氣qi體ti穩wen定ding性xing試shi驗yan是shi測ce定ding標biao準zhun氣qi體ti濃nong度du值zhi隨sui時shi間jian的de變bian化hua曲qu線xian,可ke根gen據ju各ge種zhong氣qi體ti的de特te點dian,采cai用yong不bu同tong的de測ce定ding方fang法fa。為wei了le使shi測ce定ding結jie果guo準zhun和he具ju有you可ke比bi性xing,不bu僅jin要yao使shi用yong高gao精jing度du的de測ce定ding方fang法fa,而er且qie在zai每mei次ci測ce定ding之zhi前qian都dou要yao用yong新xin配pei製zhi的de基ji準zhun標biao準zhun氣qi體ti來lai校xiao準zhun測ce定ding儀yi器qi。標biao準zhun氣qi體ti濃nong度du值zhi隨sui時shi間jian的de變bian化hua.通常用變化率來表示,就是以0d測定值為而求得的不同時間裏的濃度變化百分比,可按下式計算:用變化率對時間繪製曲線,則會得到變化同線。這種變化率曲線能夠直觀地說明標準氣體的穩定性。
(3)標準氣體的有效期
通(tong)常(chang),標(biao)準(zhun)氣(qi)體(ti)的(de)使(shi)用(yong)有(you)效(xiao)期(qi)是(shi)根(gen)據(ju)穩(wen)定(ding)性(xing)試(shi)驗(yan)結(jie)果(guo)來(lai)加(jia)以(yi)確(que)定(ding)的(de)。有(you)效(xiao)期(qi)是(shi)指(zhi)濃(nong)度(du)變(bian)化(hua)率(lv)不(bu)過(guo)規(gui)定(ding)指(zhi)標(biao)的(de)時(shi)間(jian)間(jian)隔(ge)。鋼(gang)瓶(ping)標(biao)準(zhun)氣(qi)體(ti)濃(nong)度(du)很(hen)低(di)時(shi),其(qi)濃(nong)度(du)變(bian)化(hua)較(jiao)大(da),因(yin)此(ci)從(cong)穩(wen)定(ding)性(xing)的(de)現(xian)點(dian)來(lai)看(kan),組(zu)分(fen)氣(qi)體(ti)濃(nong)度(du)越(yue)高(gao)越(yue)穩(wen)定(ding)。高(gao)壓(ya)鋼(gang)瓶(ping)標(biao)準(zhun)氣(qi)體(ti)的(de)濃(nong)度(du)即(ji)使(shi)在(zai)5×10-5以yi上shang,鋼gang瓶ping中zhong的de組zu分fen氣qi體ti仍reng在zai發fa生sheng變bian化hua,所suo以yi一yi般ban把ba能neng夠gou保bao標biao準zhun值zhi的de有you效xiao期qi定ding為wei半ban年nian至zhi一yi年nian。如ru果guo有you些xie準zhun氣qi體ti已yi超chao過guo有you效xiao期qi,但dan容rong器qi中zhong的de殘can壓ya在zai8MPa(80atm)yishangshikeyizaiciceding,quedingzhihoujixushiyong。suizheyonghuxiaohaobiaozhunqitiercanyabianhuashi,beixifuzairongqineibishangdegezhongchengfenqitibianjiexixialai,shinongduzhifashengbianhua。yibanguiding,gaoyagangpingbiaozhunqitidecanyadiyu1MPa(l0atm)時,停(ting)止(zhi)使(shi)用(yong)。不(bu)推(tui)薦(jian)對(dui)過(guo)期(qi)的(de)氣(qi)體(ti)標(biao)準(zhun)物(wu)質(zhi)重(zhong)新(xin)檢(jian)驗(yan)定(ding)值(zhi)以(yi)後(hou)使(shi)用(yong)。因(yin)為(wei)定(ding)值(zhi)方(fang)法(fa)還(hai)是(shi)稱(cheng)量(liang)法(fa)準(zhun),檢(jian)驗(yan)定(ding)值(zhi)的(de)量(liang)值(zhi)來(lai)源(yuan)還(hai)是(shi)稱(cheng)量(liang)法(fa)的(de)標(biao)準(zhun)物(wu)質(zhi),當(dang)然(ran)沒(mei)有(you)直(zhi)接(jie)稱(cheng)量(liang)法(fa)的(de)量(liang)值(zhi)準(zhun)。
目前國內氣瓶製造及內壁處理工藝與國外仍有較大差距,為了提高標準氣體的穩定性,對某些低濃度高活性組分(如H2S,Cl2 NO NO2等)標準氣體建議采用國外瓶進行配製。
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