N.G. Domostroeva, A.G. Chunovkina. with contribution by:

Transcription

1 СOOMET.M.V-K1 key ntercomparson of lqud vscosty measurements N.G. Domostroeva, A.G. Chunovkna wth contrbuton by: Natala Domostroeva: D.I. Mendeleyev Insttute for Metrology, Russan Federaton Kalna Dmtrova: Natonal Centre of Metrology, Bulgara Lda Bolohovceva: Ukrmetrteststandart, Ukrane Nna Kharova: BelGIM, Republc of Belarus 1

2 Table of Contents 1. INTRODUCTION FIRST REGIONAL COMPARISON OF LIQUID VISCOSITY MEASUREMENTS (COOMET PROJECT ) RESULTS OF THE KEY COMPARISON PROCEDURE OF THE LINK COOMET KC and CIPM KC REFERENCES Appendx A Appendx A

3 1. INTRODUCTION The measurement of vscosty s very mportant for many ndustral felds (petroleum products, polymers, food, pharmaceutcs and others). The need for traceablty mpels an ncreasng number of natonal accredted laboratores to provde vscometer calbratons. The organzaton of the frst СOOMET key comparson on vscosty was planned at the 9 th Meetng of COOMET TC 1.6 Mass and ated quanttes that took place on 1 Aprl, 004 at the Slovak Metrologcal Insttute, Bratslava. Natonal standards of vscosty are presented by a set of capllary vscometers wth overlappng measurng ranges coverng the range of knematc vscostes from about 0, mm /s to above mm /s. The vscometer types that are used for ths purpose are suspended-level (Ubbelohde) vscometers. D.I Mendeleyev VNIIM, (RF) agreed to be the plot laboratory for the comparson. Ths comparson was carred out accordng to the rules set forth by the Mutual recognton of natonal measurement standards and of measurement certfcates ssued by natonal metrologcal nsttutes (MRA) and was regstered as a regonal key comparson. The am of ths frst COOMET key comparson (CCM.V-S1) was to determne the degrees of equvalence between ndvdual NMIs and to compare them wth the reference values (KCRV) obtaned n the frst key comparson CCM (CCM.V-K1) that was conducted n 00. Three samples of Newtonan lquds wth nomnal knematc vscostes of 0 mm²/s at 0 C, 100 mm²/s at 0 C, 1000 mm²/s at 0 C, were used.

4 Frst regonal key comparson of lqud vscosty measurements (COOMET Project ) The followng laboratores partcpated n ths key comparson: - BelGIM, ( Belorussan State Insttute for Metrology, Republc of Belarus); - NCM, (Natonal Centre of Metrology, Bulgara); - Ukrmetrteststandart, (Ukranan Metrologcal Test Standart, Ukrane); - VNIIM, (D.I. Mendeleyev Insttute for Metrology, Russan Federaton); The measurements were carred out on samples of three standard lquds provded by VNIIM as the plot laboratory. Detals of the comparson procedure are specfed n the Techncal Protocol. Techncal Protocol for COOMET key comparson Purpose of ths document The purpose of ths document s to provde the partcpatng laboratores wth nstructons for the handlng of the lquds and to report on the measurement results, the measurng procedure and the apparatus. It s mportant that all nstructons gven n ths document be followed. Ths wll ensure that the measurement data are obtaned under comparable condtons and are presented n the same format. Any devaton from the nstructons has to be reported to the Plot Laboratory. - Measurement program for knematc vscosty: Standard lqud REV 0 at 0 0 C, approxmate knematc vscosty: 0 mm /s, densty: 0, 8667 g/sm ; Standard lqud REV 100 at 0 0 C, approxmate knematc vscosty: 100 mm /s, densty: 0,8787 g/sm ; Standard lqud REV 1000 at 0 0 C, approxmate knematc vscosty: 4

5 1000 mm /s, densty: 0,89050 g/sm ; - All standard lquds are the mx of mneral ols. For all lquds, the long-term stablty of the knematc vscosty s better than 0,1% over sx months. - The standard lquds are packed nto the 50 ml bottles made of dark glass. - The uncertanty of the vscosty data s stated to be atve to the uncertanty for water, whch means that the uncertanty of the water value - [1 ] s not taken nto account. Tmetable: December 004 (plot laboratory): Malng of standard lquds, data sheets, and techncal report to the partcpants March 005 (all partcpants): Start of the comparson June 005 (all partcpants): Completon of measurements July 005 (all partcpants): Submsson of results to the plot laboratory September 005 (plot laboratory): Submsson of draft report to the partcpants March 006 (all partcpants): COOMET meetng at VNIIFTRI, Moscow, dscusson of results December 006 (plot laboratory): Submsson of the fnal report to the partcpants October 007 (all partcpants): COOMET meetng at BelGIM, Mnsk, dscusson of the Draft B 5

6 . Results of the key comparson The am of the comparson was to determne the degree of equvalence of the natonal standards of Belarus, Ukrane and Bulgara aganst the standards of the natonal metrologcal nsttutes (NMI) that took part n the CCM.V-K1 [ ] comparson. To acheve ths goal the followng tasks were carred out: Transformaton of ntal data of comparson and evaluaton of ther uncertanty Calculaton of degrees of equvalence and correspondng uncertantes; Determnaton of the best uncertanty of measurements reported to the partcpants; Methods of measurements used by the partcpants n the comparson All partcpants used two suspended-level (Ubbelohde) vscometers wth close calbraton constants, as natonal standards. The workng equaton s gven by: γ = К τ, where γ -knematc vscosty, К-vscometer constant, τ flow tme, с The uncertanty s calculated accordng to the nternatonal Gude [ ] and are specfed for k=. The atve overall uncertanty n the measurement of the knematc vscosty ( U ν ), calculated by each partcpant s: 1 ( S ) + ( S ) + [( S ) ( S ) ] U γ = k ϑγ T + t S k - atve uncertanty constant К, (from certfcate of calbraton); S t atve uncertanty of the tme devce; Sϑγ - atve uncertanty of thermometer, gradent of temperature n the thermostat bath and temperature coeffcent of lqud vscosty; S T - atve uncertanty of flow tme measurements; Results of the comparson measurements are shown n Table 1. 6

7 Table 1: Results of the CCM.V-K1 Comparson. Partcpants Lqud "0" Lqud"100" Lqud"100" VNIIM ν, mm /s 8,557 91, , 10 u ν,0,4,6 ν, mm /s 8,545 91, ,0 BELGIM 10 u ν 4, 5,4,0 ν, mm /s 8,59 91, ,1 UKRMETR 10 u ν,4,,4 ν, mm /s 8,59 91,7 100,6 NСМ 10 u ν,0,, 10 u ν overall atve measurement uncertanty, obtaned by each partcpant (к=); The measurement results for standard lqud REV 0 at 0 0 C, standard lqud REV 100 at 0 0 C and standard lqud REV 1000 are gven n Table 1. The data from Table 1 are also plotted n Fg.1, Fg. and Fg. n the Appendx Procedure for lnkng of COOMET KC and CIPM KC The lnkng of the results of the comparsons was fulflled across the results of measurements obtaned n the CIPM and COOMET comparsons, respectvely. As the nomnal values of vscosty obtaned n RMO and CIPM comparsons were dfferent, so the basc crteron at the choce of par values obtaned by VNIIM n the both comparsons were used as dentcal measurement sets. So the results for Lqud 0 were lnked to Lqud 10 (Lqud A), those for Lqud 100 were lnked to Lqud 400 (Lqud B), those for Lqud 1000 to Lqud 100 (Lqud B1). For the evaluaton of data the procedure specfed n the Recommendaton of the COOMET for evaluaton of key comparson data was followed. The data of the CCM.V-K1 [ ] key comparson for three lqud samples - Lquds A, B1, B (key sgnfcance) χ ref, the data obtaned by the lnkng nsttute (VNIIM) χ, and the respectve ate uncertanty are shown n Table. 7

8 Table u x ref, ( ) x, ( x ) x ref u Lqud «10 / 0 C» (Lqud A) , 1.8 9,6558, 1.0 Lqud «400 / 100 C» (Lqud B) , , 1. Lqud «100 / 0 C» (Lqud B1) , ,90 1. Multplcaton correcton c s used for calculatng transformed data. x ~, ( ) (1 ) ( ~ c = u c = u x ), ρ x Where x~ results of measurements obtaned by VNIIM n the СOOMET KC; ρ = 0.76 coraton coeffcent for the results of measurements made at VNIIM calculated from the analyss of the measurement uncertantes budget. The calculaton results of the coeffcents of transformed data are shown n the Tables А1-1, А1-, А1-. The transformed data of comparson and respectve uncertantes are calculated by: ~ ~, ( ~ ( ~ ) ) ( ) ( ~ ) (1 ) x = c x u x = u x + u c = u x + ρ u ( x ). The degrees of equvalence and respectve uncertantes are calculated by: ( ) ( ~ ~ u x =, ( ) = ) + ( ) + (1 ref d ) ( ) 1 x xref u d c u x u xref ρ u x. ( ) u x For the convenence of comparng the results obtaned n COOMET key comparsons wth those of the CIPM KC the degrees of equvalence are also presented as a rato wth respect to the reference value of the key comparson: Δ = x d ref, U ( Δ u( d ) = x An objectve confrmaton of the uncertantes clamed by the partcpants s the conformance to the nequaton Δ U ( Δ ). The results of the evaluaton of data obtaned for all lquds used n the comparson are tabulated n Tables A1-1, A1-, A1- (Apendx A1). Fgs, А-1 to А- (Apendx A) show the results of CCM.V-K1 comparson and the transformed results of the CCM.V-S1 comparson. Green hghlghted are the results obtaned by the lnkng laboratory (VNIIM). The transformed results of the partcpants n the CCM.V-S1 comparson are blue colored. The results are presented as devatons from the KCRV of CCM.V-K1 and as the clamed standard devatons of the measurement results. It s to be ponted out that standard uncertantes are shown and not extended ones, therefore some ntervals do not ref ). 8

9 cross. As mentoned above, all laboratores have confrmed the clamed measurement uncertantes. 5. References 1 ISO TR 666: Vscosty of Water (1998). CCM.V-K1 Intercomparson, Gunther Klngenberg and Harro Bauer PTB. Gude to the Expresson of Uncertanty n Measurement? Corrected and reprnted 1995, Internatonal Organzaton of Standardzaton (Geneva, Swtzerland) 4 The Evaluaton of Key Comparson Data, M.G. Cox, Metrologa, 00, 9,

10 Table А1-1. Lqud «0» Laboratory Intal data CCM.V K-1 Transformaton data Degree of equvalence ~ c, u ( ) x~ x, u ( c) ~ u ~ ) x ( x, d u ( d ) 10 U ( ) 10 BELGIM , UKRMETR NCM ~ VNIIM x = ( ~ x ) = 1.0 u Table А1- Lqud «100» Laboratory Intal data CCM.V K-1 Transformaton data Degree of equvalence ~ c, u ( ) x~ x, u ( c) ~ u ~ ) x ( x, d u ( d ) 10 U ( ) 10 BELGIM , UKRMETR NCM ~ VNIIM x = ~ ( x ) = 1. u

11 Таble А1-. Lqud «1000» Laboratory Intal data CCM.V K-1 Transformaton data Degree of equvalence ~ c, u ( ) x~ x, u ( c) ~ u ~ ) x ( x, d u ( d ) 10 U ( ) 10 BELGIM , UKRMETR NCM ~ VNIIM x = ( ~ x ) = 1. u

12 На рисунках 1 приведены результаты сличений ССМ.V-K1 и трансформированные результаты CCM.V-S1. Зеленым цветом выделены результаты ВНИИМ им.д.и.мендлеева, который выступает в качестве связующего института. Синим цветом представлены трансформированные результаты участников CCM.V-S1 сличений. Результаты представлены как отклонения от опорного значения ключевых сличений ССМ.V-K1 и заявленные стандартные неопределенности результатов измерений. Пунктирной горизонтальной линией изображена стандартная неопределенность опорного значения. Особо отметим, что приведены стандартные неопределенности, а не расширенные, поэтому некоторые интервалы не пересекаются. Как уже было показано выше, все институты подтвердили заявленные неопределенности измерений.

13 Appendx A Fg -1.

14 Fgz -. Fg -.

15