校準實驗室該如何進行能力驗證？
2018-08-03
作者(zhe)：
瀏(liu)覽數：1508
能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)屬于(yu)(yu)一種(zhong)監(jian)督手(shou)段和(he)評(ping)估活動, 其(qi)主要(yao)落(luo)實(shi)部門是(shi)相(xiang)關認(ren)可(ke)機(ji)構。能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)的(de)(de)(de)(de)最(zui)終目(mu)的(de)(de)(de)(de)是(shi)提(ti)升實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)的(de)(de)(de)(de)質量管(guan)理水(shui)平和(he)相(xiang)應的(de)(de)(de)(de)校(xiao)準(zhun)(zhun)水(shui)平。在(zai)實(shi)際的(de)(de)(de)(de)能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)過程中, 主要(yao)采取兩種(zhong)技(ji)術措(cuo)施(shi): (1) 評(ping)審組嚴格按照相(xiang)關能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)標準(zhun)(zhun)對實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)現(xian)場情(qing)況及(ji)功(gong)能(neng)(neng)進行評(ping)判(pan); (2) 在(zai)依(yi)靠能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)的(de)(de)(de)(de)基(ji)礎上, 準(zhun)(zhun)確判(pan)斷實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)質量管(guan)理和(he)校(xiao)準(zhun)(zhun)能(neng)(neng)力(li)。在(zai)實(shi)現(xian)兩種(zhong)措(cuo)施(shi)的(de)(de)(de)(de)有(you)效結合之后, 就可(ke)以從根本上提(ti)升實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)校(xiao)準(zhun)(zhun)結果的(de)(de)(de)(de)準(zhun)(zhun)確性和(he)有(you)效性。能(neng)(neng)力(li)驗(yan)(yan)(yan)(yan)(yan)(yan)證(zheng)(zheng)(zheng)是(shi)認(ren)可(ke)機(ji)構評(ping)價(jia)實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)技(ji)術能(neng)(neng)力(li)的(de)(de)(de)(de)重要(yao)手(shou)段, 是(shi)判(pan)定(ding)其(qi)申報認(ren)可(ke)項目(mu)和(he)獲準(zhun)(zhun)項目(mu)技(ji)術能(neng)(neng)力(li)的(de)(de)(de)(de)重要(yao)依(yi)據(ju), 是(shi)確定(ding)實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)對特定(ding)實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)或測量能(neng)(neng)力(li)的(de)(de)(de)(de)重要(yao)方(fang)式, 是(shi)監(jian)控實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)持續能(neng)(neng)力(li)的(de)(de)(de)(de)有(you)效方(fang)法, 也(ye)是(shi)實(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室(shi)(shi)(shi)用于(yu)(yu)內部質量控制(zhi)的(de)(de)(de)(de)外部補(bu)充措(cuo)施(shi)。
能力驗證概(gai)念
能(neng)力(li)驗(yan)證(zheng), 即利用實(shi)驗(yan)室(shi)(shi)間比對, 按照預(yu)先制定的(de)準則評(ping)價(jia)參加(jia)(jia)者的(de)能(neng)力(li)。對一個參加(jia)(jia)者進行“一對一”能(neng)力(li)評(ping)價(jia)的(de)能(neng)力(li)驗(yan)證(zheng)計(ji)劃(hua)稱為“測(ce)量審核”。能(neng)力(li)驗(yan)證(zheng)的(de)實(shi)質就是在比較實(shi)驗(yan)室(shi)(shi)情(qing)況的(de)基礎上(shang), 評(ping)價(jia)實(shi)驗(yan)室(shi)(shi)校準能(neng)力(li)的(de)一種活動。
國(guo)家認可(ke)(ke)委 (CNAS) 對(dui)獲(huo)得認可(ke)(ke)的(de)(de)實驗(yan)室(shi)在(zai)能(neng)力(li)驗(yan)證(zheng)(zheng)方面(mian)的(de)(de)頻(pin)(pin)次(ci)要(yao)求(qiu)為:只要(yao)是(shi)存在(zai)可(ke)(ke)獲(huo)得的(de)(de)能(neng)力(li)驗(yan)證(zheng)(zheng), 合格評定(ding)校(xiao)準(zhun)實驗(yan)室(shi)應滿足國(guo)家認可(ke)(ke)委公(gong)布的(de)(de)能(neng)力(li)驗(yan)證(zheng)(zheng)領(ling)域和頻(pin)(pin)次(ci)要(yao)求(qiu)。對(dui)于CNAS能(neng)力(li)驗(yan)證(zheng)(zheng)領(ling)域和頻(pin)(pin)次(ci)表中(zhong)未(wei)列入(ru)的(de)(de)領(ling)域 (子領(ling)域) , 只要(yao)存在(zai)可(ke)(ke)獲(huo)得的(de)(de)能(neng)力(li)驗(yan)證(zheng)(zheng), 合格評定(ding)校(xiao)準(zhun)實驗(yan)室(shi)就(jiu)要(yao)在(zai)每個認可(ke)(ke)周期(qi)內至(zhi)少(shao)參加一次(ci)。
能(neng)力驗(yan)(yan)(yan)證(zheng)的(de)(de)有效(xiao)方式主要有以下(xia)幾種: (1) 參(can)加(jia)國(guo)家認(ren)可(ke)委(wei)或(huo)國(guo)家認(ren)監(jian)(jian)委(wei)組(zu)織的(de)(de)能(neng)力驗(yan)(yan)(yan)證(zheng)計(ji)(ji)劃(hua)或(huo)政府計(ji)(ji)量(liang)部門組(zu)織的(de)(de)實驗(yan)(yan)(yan)室計(ji)(ji)量(liang)比對活動; (2) 參(can)加(jia)國(guo)家認(ren)可(ke)委(wei)認(ren)可(ke)的(de)(de)能(neng)力驗(yan)(yan)(yan)證(zheng)提供者在獲(huo)準的(de)(de)認(ren)可(ke)范(fan)圍內開(kai)展的(de)(de)能(neng)力驗(yan)(yan)(yan)證(zheng)計(ji)(ji)劃(hua); (3) 參(can)加(jia)國(guo)家認(ren)可(ke)委(wei)認(ren)可(ke)的(de)(de)測(ce)量(liang)審(shen)核活動; (4) 如果沒有適當的(de)(de)能(neng)力驗(yan)(yan)(yan)證(zheng)領域, 可(ke)通過結果監(jian)(jian)控(kong)(kong)等質量(liang)監(jian)(jian)控(kong)(kong)方式進行內部質量(liang)控(kong)(kong)制。
在能力(li)(li)驗證實(shi)(shi)施(shi)過(guo)程中, 通(tong)(tong)常由(you)主導實(shi)(shi)驗室(shi)(shi)提(ti)供傳(chuan)遞(di)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)、負責編(bian)寫實(shi)(shi)施(shi)方案、匯(hui)總處理最后(hou)(hou)的(de)(de)(de)(de)(de)(de)數據以及編(bian)寫最后(hou)(hou)的(de)(de)(de)(de)(de)(de)結(jie)果報告。參(can)(can)加的(de)(de)(de)(de)(de)(de)實(shi)(shi)驗室(shi)(shi)按照實(shi)(shi)施(shi)方案完成比對實(shi)(shi)驗, 并提(ti)交報告。在傳(chuan)遞(di)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)的(de)(de)(de)(de)(de)(de)選擇過(guo)程中, 應充分考慮(lv)傳(chuan)遞(di)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)的(de)(de)(de)(de)(de)(de)短期(qi)穩(wen)定性(xing)(xing)和長期(qi)穩(wen)定性(xing)(xing)變化會給結(jie)果帶來(lai)的(de)(de)(de)(de)(de)(de)影響, 因此(ci)可選取重復性(xing)(xing)和穩(wen)定性(xing)(xing)比較好的(de)(de)(de)(de)(de)(de)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)作(zuo)(zuo)為(wei)傳(chuan)遞(di)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)。根據傳(chuan)遞(di)標(biao)(biao)(biao)準(zhun)(zhun)(zhun)本身(shen)的(de)(de)(de)(de)(de)(de)特性(xing)(xing), 可將穩(wen)定偏差作(zuo)(zuo)為(wei)結(jie)果不確定度的(de)(de)(de)(de)(de)(de)一個分量考慮(lv)。通(tong)(tong)常, 能力(li)(li)驗證的(de)(de)(de)(de)(de)(de)參(can)(can)考值由(you)主導實(shi)(shi)驗室(shi)(shi)確定或(huo)由(you)各(ge)參(can)(can)比實(shi)(shi)驗室(shi)(shi)的(de)(de)(de)(de)(de)(de)平均值、加權平均值決(jue)定。
驗證能力數據的處理方法研究
能力驗(yan)證(zheng)結果一般采用歸(gui)一化(hua)偏(pian)差(cha)En值進(jin)行合(he)格(ge)(ge)評(ping)定(ding)。實(shi)驗(yan)室比對(dui)、計量標(biao)準結果驗(yan)證(zheng)和(he)儀器(qi)設備期間核查等(deng)一般都采用En值進(jin)行合(he)格(ge)(ge)評(ping)定(ding)。
En值的數學表達式為:
式 (1) 中:Xlab為參加(jia)(jia)實驗(yan)室的測量結(jie)(jie)果;Xref為參考(kao)(kao)值;Ulab為參加(jia)(jia)實驗(yan)室測量結(jie)(jie)果的擴展不(bu)確(que)定度;Uref為參考(kao)(kao)值的擴展不(bu)確(que)定度。
En值的判(pan)定(ding):當(dang)En值≤1 時(shi), 結(jie)果(guo)(guo)滿(man)(man)意(yi);En值>1 時(shi), 結(jie)果(guo)(guo)不滿(man)(man)意(yi)。當(dang)結(jie)果(guo)(guo)不滿(man)(man)意(yi)時(shi), 參加實(shi)驗(yan)室必須查(cha)找原因(yin), 及時(shi)采(cai)取糾正(zheng)措(cuo)施。另外, 結(jie)果(guo)(guo)不滿(man)(man)意(yi)的實(shi)驗(yan)室應再次參加實(shi)驗(yan)室間比(bi)對或測量審核活動(dong)驗(yan)證所(suo)采(cai)取措(cuo)施的有效(xiao)性, 否則(ze)認可機構將(jiang)取消該實(shi)驗(yan)室的認可資格。
從En值(zhi)的(de)數學(xue)表達式中可以(yi)看出, 影響En值(zhi)的(de)因素有兩個, 即參加實(shi)驗(yan)(yan)(yan)室(shi)的(de)測(ce)(ce)量(liang)(liang)(liang)結(jie)果和參加實(shi)驗(yan)(yan)(yan)室(shi)測(ce)(ce)量(liang)(liang)(liang)結(jie)果的(de)擴(kuo)展不(bu)(bu)確(que)定(ding)度。要想使En值(zhi)處于(yu)合(he)理(li)的(de)范(fan)圍內(nei), 就必(bi)須保證測(ce)(ce)量(liang)(liang)(liang)結(jie)果的(de)準(zhun)確(que)性(xing)和擴(kuo)展不(bu)(bu)確(que)定(ding)度的(de)合(he)理(li)性(xing)。由式 (1) 可得(de), 在測(ce)(ce)量(liang)(liang)(liang)誤差不(bu)(bu)變的(de)情(qing)況下, 測(ce)(ce)量(liang)(liang)(liang)不(bu)(bu)確(que)定(ding)度越(yue)小, En值(zhi)越(yue)大。因此(ci), 在評(ping)定(ding)不(bu)(bu)確(que)定(ding)度時, 不(bu)(bu)要為了(le)追求實(shi)驗(yan)(yan)(yan)室(shi)校準(zhun)能力, 而把不(bu)(bu)確(que)定(ding)度評(ping)得(de)過小。
應用實(shi)例分析
以某年燃氣(qi)表(biao)(biao)(biao)檢(jian)定(ding)(ding)(ding)裝置的(de)(de)(de)(de)(de)量(liang)(liang)(liang)值(zhi)(zhi)比(bi)(bi)(bi)對為例, 主(zhu)導(dao)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室為A, 共有B, C, D, E, F, G6 家(jia)參(can)比(bi)(bi)(bi)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室。傳遞標(biao)準(zhun)(zhun)(zhun)由主(zhu)導(dao)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室提供, 主(zhu)導(dao)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室經過(guo)大量(liang)(liang)(liang)的(de)(de)(de)(de)(de)穩(wen)定(ding)(ding)(ding)性試(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)后, 最終選取(qu)了(le)一(yi)臺G2.5 的(de)(de)(de)(de)(de)燃氣(qi)表(biao)(biao)(biao)作為傳遞標(biao)準(zhun)(zhun)(zhun)。在Qmax、0.2Qmax和(he)Qmin三(san)個流量(liang)(liang)(liang)點(dian)(dian)下進行(xing)比(bi)(bi)(bi)對試(shi)驗(yan)(yan)(yan)(yan)(yan)(yan), Qmax和(he)0.2Qmax為正式比(bi)(bi)(bi)對流量(liang)(liang)(liang)點(dian)(dian), Qmin為輔助(zhu)比(bi)(bi)(bi)對流量(liang)(liang)(liang)點(dian)(dian)。各參(can)比(bi)(bi)(bi)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室給出的(de)(de)(de)(de)(de)比(bi)(bi)(bi)對結果(guo)(guo)應包括各檢(jian)定(ding)(ding)(ding)點(dian)(dian)的(de)(de)(de)(de)(de)平均(jun)示(shi)值(zhi)(zhi)誤差和(he)相應的(de)(de)(de)(de)(de)擴展不(bu)確定(ding)(ding)(ding)度。主(zhu)導(dao)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室以比(bi)(bi)(bi)對前的(de)(de)(de)(de)(de)測量(liang)(liang)(liang)結果(guo)(guo)為參(can)比(bi)(bi)(bi)結果(guo)(guo), 比(bi)(bi)(bi)對試(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)期間(jian)的(de)(de)(de)(de)(de)測量(liang)(liang)(liang)結果(guo)(guo)參(can)與比(bi)(bi)(bi)對結果(guo)(guo)評(ping)價(jia)中(zhong)標(biao)準(zhun)(zhun)(zhun)不(bu)確定(ding)(ding)(ding)度穩(wen)定(ding)(ding)(ding)性分量(liang)(liang)(liang)計算, 比(bi)(bi)(bi)對的(de)(de)(de)(de)(de)參(can)考值(zhi)(zhi)采用(yong)各實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室的(de)(de)(de)(de)(de)加權平均(jun)值(zhi)(zhi)。表(biao)(biao)(biao)1 為各參(can)比(bi)(bi)(bi)實(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)室對傳遞標(biao)準(zhun)(zhun)(zhun)進行(xing)測量(liang)(liang)(liang)的(de)(de)(de)(de)(de)示(shi)值(zhi)(zhi)誤差和(he)擴展不(bu)確定(ding)(ding)(ding)度, 表(biao)(biao)(biao)2 為傳遞標(biao)準(zhun)(zhun)(zhun)比(bi)(bi)(bi)對結果(guo)(guo)En值(zhi)(zhi)。
表1 各參比實驗室對傳遞標準進行測量的示值誤差和擴展不確定度
表2 傳遞標準比對結果En值
由比對(dui)結果(guo)(guo)可(ke)(ke)知, 6 個(ge)(ge)參(can)比實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)中(zhong)只有(you)G實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)結果(guo)(guo)不滿意(yi), 兩個(ge)(ge)比對(dui)流量(liang)點En值均大(da)于1, 說明G實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)的(de)(de)測量(liang)結果(guo)(guo)不符合實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)要求的(de)(de)擴展不確定(ding)(ding)度。G實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)應(ying)分(fen)析其(qi)中(zhong)原因, 采(cai)取(qu)糾正措施, 然后再次(ci)(ci)參(can)加實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)間比對(dui)或測量(liang)審核活(huo)(huo)動(dong)驗(yan)(yan)證所采(cai)取(qu)措施的(de)(de)有(you)效性。其(qi)他(ta)參(can)比實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)結果(guo)(guo)均滿意(yi)。實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)可(ke)(ke)將(jiang)此次(ci)(ci)比對(dui)作(zuo)為一次(ci)(ci)能力(li)驗(yan)(yan)證活(huo)(huo)動(dong), 在認可(ke)(ke)周期內(nei)無需再參(can)加其(qi)他(ta)組織的(de)(de)能力(li)驗(yan)(yan)證活(huo)(huo)動(dong)。結合上表(biao)中(zhong)的(de)(de)數據不難發(fa)現(xian), F實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)在Qmax這個(ge)(ge)點比E實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)距離參(can)考值更遠(yuan), 但En值卻比E實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)小(xiao), 原因是F實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)的(de)(de)擴展不確定(ding)(ding)度0.56%遠(yuan)大(da)于E實(shi)(shi)(shi)驗(yan)(yan)室(shi)(shi)(shi)的(de)(de)0.29%.
在進行能(neng)(neng)力驗(yan)(yan)證后(hou)(hou), 各(ge)實驗(yan)(yan)室(shi)特別是結果不滿意的(de), 就(jiu)能(neng)(neng)明確尚待解(jie)決(jue)的(de)相關問題, 并(bing)在找出問題產生(sheng)的(de)原因(yin)之后(hou)(hou), 采取有效的(de)解(jie)決(jue)措施(shi), 最終提升實驗(yan)(yan)室(shi)的(de)質(zhi)量(liang)管(guan)理能(neng)(neng)力。因(yin)此, 在校準(zhun)實驗(yan)(yan)室(shi)質(zhi)量(liang)管(guan)理中, 能(neng)(neng)力驗(yan)(yan)證和評估(gu)的(de)應用(yong)意義重大(da)。
