福州標準氣體的穩定性與有效期
福州標準氣體的穩定性與有效期
biaozhunqitidewendingxingshipeizhiheshiyongguochengzhongdeguanjianwenti。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、飽(bao)和(he)處(chu)理(li)等(deng)。飽(bao)和(he)處(chu)理(li)是(shi)為(wei)了(le)防(fang)止(zhi)容(rong)器(qi)內(nei)壁(bi)因(yin)吸(xi)附(fu)或(huo)解(jie)吸(xi)帶(dai)來(lai)的(de)影(ying)響(xiang),先(xian)對(dui)容(rong)器(qi)內(nei)壁(bi)進(jin)行(xing)鏡(jing)麵(mian)研(yan),塗(tu)上(shang)防(fang)氧(yang)化(hua)漆(qi),然(ran)後(hou)把(ba)高(gao)濃(nong)度(du)氣(qi)體(ti)充(chong)人(ren)容(rong)器(qi)內(nei)並(bing)放(fang)置(zhi)10d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)確(que)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:
變化率(%的測定)=[(實測值)-(0d值) ]/ (0d的測定值) x100
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
tongchang,biaozhunqitideshiyongyouxiaoqishigenjuwendingxingshiyanjieguolaijiayiquedingde。youxiaoqishizhinongdubianhualvbuguoguidingzhibiaodeshijianjiange。gangpingbiaozhunqitinongduhendishi,qinongdubianhuajiaoda,yincicongwendingxingdexiandianlaikan,zufenqitinongduyuegaoyuewending。gaoyagangpingbiaozhunqitidenongdujishizai5×10-5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)過(guo)有(you)效(xiao)期(qi),但(dan)容(rong)器(qi)中(zhong)的(de)殘(can)壓(ya)在(zai)8MPa(80atm)以yi上shang時shi可ke以yi再zai次ci測ce定ding,確que定ding值zhi後hou繼ji續xu使shi用yong。隨sui著zhe用yong戶hu消xiao耗hao標biao準zhun氣qi體ti而er殘can壓ya變bian化hua時shi,被bei吸xi附fu在zai容rong器qi內nei壁bi上shang的de各ge種zhong成cheng分fen氣qi體ti便bian解jie吸xi下xia來lai,使shi濃nong度du值zhi發fa生sheng變bian化hua。一yi般ban規gui定ding,高gao壓ya鋼gang瓶ping標biao準zhun氣qi體ti的de殘can壓ya低di於yu1MPa(l0atm)時,停止使用。
butuijianduiguoqideqitibiaozhunwuzhizhongxinjianyandingzhiyihoushiyong。yinweidingzhifangfahaishichengliangfazhun,jianyandingzhideliangzhilaiyuanhaishichengliangfadebiaozhunwuzhi,dangranmeiyouzhijiechengliangfadeliangzhizhunque。
返回列表