Final Report. CCM.V-K1 intercomparison

Transcription

1 Fnal Report CCM.V-K ntercomparson Günther Klngenberg and Harro Bauer PTB Abstract Ths report descrbes the frst CCM key comparson n capllary vscometry at eleven Natonal Metrology Insttutes (NMIs) whch was carred out between May and July Furthermore, seven NMIs whch do not mantan an ndependent vscosty scale took part n ths comparson. Fve Newtonan lquds wth nomnal knematc vscostes of 0 mm²/s at 20 C, 300 mm²/s at 20 C, 400 mm²/s at 40 C, 40 mm²/s at 00 C and mm²/s at 20 C were used to determne the degrees of equvalence between the ndvdual NMIs and the key comparson reference value (KCRV). The relatve standard uncertanty of the KCRV extends from 0,05% at 400 mm²/s to 0,5% at 40 mm²/s and 00 C. From the total number of 74 measurements carred out by all the partcpatng NMIs, 8 showed a devaton from the KCRV greater than was covered by the measurement uncertanty.

2 2 CONTENTS Introducton 3 2 Partcpants 3 3 Vscosty scales of partcpants n the ntercomparson 5 4 Lqud samples 6 5 Organzaton of the ntercomparson 7 6 Comments on the ntercomparson 7 7 Results of the CCM.V K ntercomparson 8 8 References

3 3. Introducton The Ad Hoc Workng Group on Vscosty at BIPM decded on October 26, 200, to organze a frst key comparson on vscosty wth PTB actng as the plot laboratory. All laboratores elgble under the rules of the Mutual Recognton Arrangement (MRA) were nvted to partcpate n ths key comparson. The key comparson reference value should, however, be based only on the results of laboratores mantanng an ndependent vscosty scale. Eleven partcpants tracng back ther vscosty scale drectly to the vscosty of water [], and seven addtonal partcpants took part n ths key comparson. The am of the present ntercomparson was to check the vscosty scale at low vscostes (close to the vscosty of water), n partcular wth respect to knetc energy correcton and surface tenson correcton (standard lqud A) to check the step up procedure from water to mm²/s (standard lqud C) to check the vscosty measurements at temperatures up to 00 C (standard lqud B). 2. Partcpants Lst of laboratores mantanng an ndependent vscosty scale, and names of the persons responsble: Bureau Natonal de Métrologe Laboratore Natonal d Essas (BNM-LNE) France: Mohamed Megharf, Emmanuel Mahé Cannon Instrument Company (Cannon) USA: Rchard Hoover Central Offce of Measures (GUM) Poland: Mrs. Jadwga Nawra

4 4 Consglo Nazonale delle Rcerche Isttuto d Metrologa G. Colonnett (CNR-IMGC) Italy: Salvatore Lorefce Natonal Metrology Insttute of Japan, Natonal Insttute of Advanced Industral Scence and Technology (NMIJ/AIST) Japan: Kench Fuj, Yasumtsu Kurano Nederlands Meetnsttuut, Van Swnden Laboratorum (NM VSL) The Netherlands: Rob H. Bergmans, Mrs. Inge van Andel Natonal Research Center for Certfed Reference Materals (NRCCRM) P.R.Chna: Xu Xueln Physkalsch Technsche Bundesanstalt Braunschweg (PTB) Germany: Harro Bauer, Günther Klngenberg Slovak Insttute of Metrology / Slovenský Metrologcký Ústav (SMU) Slovaka: Dusan Trochta Marmara Arastrma Merkez / Ulusal Metroloj Ensttüsü TUBITAK (UME) Turkey: Vaht Cftc, Orhan Sakarya D.I. Mendeleyev Insttute for Metrology (VNIIM) Russan Federaton: Mrs. Natala Domostroyeva Lst of laboratores wth a scale based on other NMIs and names of the persons responsble: Bundesamt für Ech- und Vermessungswesen (BEV) Austra: Norbert Kuhn

5 5 Centro Naconal de Metrologa (CENAM) Méxco: Mrs. Sona Trujllo Insttutul Natonal de Metrologe (INM) Romana: Mrs. Ana Popescu Portuguese Insttute for Qualty (IPQ) Portugal: Carlos Neto de Castro, Mrs. Mara do Ceu Ferrera Natonal Insttute for Standards (NIS) Egypt: Mostafa Mekawy, Nabl El-Sayed Natonal Physcal Laboratory (NPL Inda) Inda: Trpurar Lal Natonal Metrology Laboratory (SIRIM Berhad) Malaysa: Mohd Fazrul Hsyam bn Mohd Nor 3. Vscosty scales of the partcpants Most of the partcpants used Ubbelohde vscometers for the basc calbraton wth water (GUM, IMGC-CNR, PTB, SMU, UME, VNIIM); three used U-tube vscometers (BNM-LNE, NMIJ/AIST, NRCCRM); one partcpant appled Ostwald vscometers (NM VSL); and one employed Cannon-Ubbelohde master vscometers, Cannon- Ubbelohde standard vscometers and Cannon-master vscometers (Cannon). In order to obtan the surface tenson correcton, dmensonal measurements of the vscometers were carred out by BNM-LNE, GUM, NRCCRM, SMU; lquds of wellknown surface tensons and vscostes were used by IMGC-CNR, PTB, UME; ASTM D 262 was appled by Cannon; specal methods were used by NMIJ/AIST, VNIIM; and n the case of the Ostwald vscometer (NM VSL), ths correcton was not necessary. For the calculaton of the knetc energy correcton term, most partcpants used the Cannon-Mannng-Bell formula [2] (BNM-LNE, GUM, NMIJ/AIST, SMU, UME); two appled the temperature dependence of the vscosty of water (IMGC-CNR, NM

6 6 VSL); one reled on a method startng from the assumpton of smlarty of vscometers of dfferent sze (PTB); one used ASTM D 446 (Cannon); and one appled an emprcal approach (VNIIM). For the step-up procedure as well as for the comparson measurements, Ubbelohde vscometers were used except by NM VSL (Ostwald vscometers); Cannon (Cannon- Ubbelohde master vscometers, Cannon-Ubbelohde standard vscometers, Cannonmaster vscometers); and NMIJ/AIST (U-tube vscometers). All addtonal partcpants used Ubbelohde vscometers wth the excepton of INM whch employed Cannon-master vscometers. Addtonal nformaton about the vscosty scales of several partcpants can be found n [3]. A booklet on ts vscosty measurement uncertantes s avalable from Cannon [4]. 4. Lqud samples The measurements were to be carred out on samples of three standard lquds provded by PTB as the plot laboratory. The standard lquds A and B were poly-αolefnes and the lqud C was a polysobutylene. For each lqud and each temperature, samples of 250 ml were suppled. Samples B, B2 and B3 were the same lqud but taken from dfferent batches. For ths reason, a dstncton was made between the standard lquds B for 20 C, B2 for 40 C and B3 for 00 C. The followng data, ncludng standard uncertantes were dssemnated by the plot laboratory: Standard lqud A at 20 C: approxmate knematc vscosty: 0 mm²/s; densty: (0,79520 ± 0,00008) g/cm³, surface tenson: (27,93 ± 0,25) mn/m Standard lqud B at 20 C: approxmate knematc vscosty: 300 mm²/s, densty: (0,84568 ± 0,0000) g/cm³, surface tenson: (30,49 ± 0,25) mn/m Standard lqud B2 at 40 C: approxmate knematc vscosty: 400 mm²/s, densty: (0,83368 ± 0,0000) g/cm³, surface tenson: (30,0 ± 0,25) mn/m Standard lqud B3 at 00 C: approxmate knematc vscosty: 40 mm²/s, densty: (0,79792 ± 0,0002) g/cm³, surface tenson: (26,34 ± 0,58) mn/m Standard lqud C at 20 C: approxmate knematc vscosty: mm²/s, densty: (0,88858 ± 0,0000) g/cm³, surface tenson: (28,85 ± 0,32) mn/m

7 7 For all standard lquds, the long-term stablty of the knematc vscosty was better than 0,% over sx months. Exposure to brght lght and hgh temperatures had to be avoded. It was not permtted to open the sealed glass bottles before the measurements were started. The ols could be heated to 70 C to facltate fllng of the vscometers. The bottles had to be closed between samplngs. 5. Organzaton of the ntercomparson: Chronology of the measurements: Aprl 26 th, 2002 (plot laboratory): Malng of the standard lquds, the report forms, the tmetable, and the techncal protocol to the partcpants May 20 th, 2002 (all partcpants): Start of the comparson measurements June 28 th, 2002 (all partcpants): Termnaton of the comparson measurements July 26 th, 2002 (all partcpants): Submsson of the results to the plot laboratory October st, 2002 * (plot laboratory): Submsson of draft report A to the partcpants November 5 th, 2002 (BIPM): 3 rd meetng of the Ad-Hoc Workng Group on Vscosty December 20 th, 2002 (plot laboratory): Submsson of draft B * As there was some delay n obtanng the measurement results from all partcpants, the Executve Secretary of the Ad-Hoc Workng Group on Vscosty agreed to extend the perod untl October 5 th, Comments on the ntercomparson The partcpants receved the samples before May 20, 2002, wth the excepton of CENAM (June 03) and VNIIM (July 09). The comparson measurements were carred out between May 20 and July 22. Some partcpants dd not measure all samples. The plot laboratory corrected the followng results to target temperature: BNM-LNE: A, B, B2, B3, C Cannon: A, B, B2, B3, C IMGC-CNR: B3 NMIJ/AIST: A, B, B2, C UME: B2, B3

8 8 CENAM: B2 INM: B2 IPQ: A, B NIS Egypt: A, B, B2, C NPL Inda: A, B, B2, B3 SIRIM: A, B3. The uncertanty of the vscosty measurement of the partcpants had to be calculated n accordance wth the Gude to the Expresson of Uncertanty n Measurement [5]. The plot laboratory provded an example of the uncertanty calculaton n case the vscosty was determned wth two vscometers of same sze (approxmately the same vscometer constant). 7. Results of the CCM.V K ntercomparson Durng the dscusson on the results of the ntercomparson at the meetng of the Ad- Hoc Workng Group on Vscosty on November 5, 2002, t was decded to use the results of all partcpants wth ndependent scales to calculate the reference value. The use of the weghted mean n connecton wth a ch-squared test to carry out an overall consstency check of the results obtaned, allows dscrepant measurements to be dentfed at the 5% level of sgnfcance for lquds A, B3 and C. It was not possble to dentfy the reason for the dscrepancy of these measurements. The calculaton of the reference value wthout usng the data from these dscrepant measurements would show a perfect stuaton that dffers from realty. Ths reflects the experence of many experts n ths feld that unexpected devatons may occasonally occur n measurements wth capllary vscometers whch are not covered by the uncertanty budget. Such devatons mght be caused by undetected cleanng problems. to use the arthmetc mean value as reference value snce t provdes the most realstc pcture of the calbraton work n vscometry. In addton, the results were calculated for the weghted mean value, the medan and the weghted medan as reference value. For all fve lquds used n ths ntercomparson the arthmetc mean value was used snce the relatve dfferences from the weghted mean and the medan dd not exceed 0,04% and 0,%, respectvely.

9 9 CCM.V-K INTERCOMPARISON Lqud A Lqud B Lqud B2 Lqud B3 Lqud C Partcpants ν u' /0-2 (mm²/s) / 0-3 D U(D) /0-2 (mm²/s) ν u' / 0-3 D U(D) ν u' / 0-3 D U(D) ν u' / 0 - (mm²/s) / 0-3 D U(D) / 0 - (mm²/s) ν u' / 0 2 (mm²/s) / 0-3 D U(D) / 0 2 (mm²/s) BNM-LNE 9,6355,00 -,6,8 28,50 2,00-4, 4,7 393,230 2,00-0,8,5 39,890,00 0, 0, ,0 2,00-0,9,4 Cannon 9,6659 0,64,4,2 286,0,77 0,5 4,2 394,208,40 0,,0 39,850,07-0,3 0, ,8 2,5 0,9,5 GUM 9,6633 0,38, 0,8 285,98 0,92 0,4 2,3 394,209 0,73 0, 0,6 3657,0,45-0,2,0 IMGC-CNR 9,5970 0,65-5,5,2 284,24 0,84 -,3 2,2 393,690 0,60-0,4 0,5 39,607 0,83-2,7 0, ,0 0,96-0,3 0,7 NMIJ / AIST 9,6590 0,28 0,7 0,6 286,49 0,42 0,9,4 394,389 0,39 0,3 0, ,3 0,6-0,3 0,5 NMI VSL 9,6530 0,80 0,,5 285,00 2,00-0,6 4,8 394,400,75 0,3, ,0 2,50 -,5,7 NRCCRM 9,6598 0,4 0,8 0,8 285,80 0,68 0,2,9 3650,0,82-0,9,3 PTB 9,6557 0,47 0,4 0,9 285,99 0,78 0,4 2, 394,60 0,74 0, 0,6 39,948 0,63 0,7 0, ,3 0,93-0,6 0,7 SMU 9,6537 0,85 0,2,5 284,0,22 -,5 3,0 393,320,2-0,8 0, ,0,80 0,2,2 UME 9,6726 0,96 2,,7 289,6,40 3,6 3,4 395,37,32,,0 39,984,5,0 0,9 3680,4,65 2,,2 VNIIM 9,6558 0,46 0,4 0,9 286,90 0,63,3,8 394,00 0,80-0, 0,6 39,996 0,8,2 0, ,0 0,96,4 0,7 Addtonal partcpants BEV 9,6640,30,2 2,5 288,20,77 2,6 4,7 394,50,5 0,4,2 CENAM 9,6566,03 0,5 2,0 288,28,26 2,7 3,4 394,33,26 0,3,0 39,950,27 0,7, 36888,6 2,53 3,0,9 INM 9,6452 0,69-0,7,4 283,68 0,70 -,9 2,0 396,929 2,40 2,9, ,,20 0,5,0 IPQ 9,6497 2,50-0,2 4,8 283,75 2,50 -,8 6,5 394,050 2,40 0,0,9 NIS Egypt 9,6824,58 3,0 3, 294,27 32,60 8,7 84,4 394,768 20,90 0,7 6, ,4 6,3 7,2 4,6 NPL Inda 9,678,26 2,0 2,5 287,37,52,8 4,0 394,950,26 0,9,0 39,997,32,2, SIRIM 9,6046 3,20-4,7 6,2 39,768 0,80 -, 0,7 Reference value νr / (mm²/s) U' / 0-3 U / 0-2 (mm²/s) νr / (mm²/s) U' U / 0-3 νr / (mm²/s) U' U / 0-3 νr / (mm²/s) U' U / 0-3 (mm²/s) / 0 - νr / (mm²/s) U' U / 0-3 (mm²/s) / 0 2 9,659,28,23 ##### 285,57 0,90,6 0, ,075 0,90 0,353 ##### 39,879 2,96,79 ##### 36587,5,77 0,649 ##### Table : Results of the CCM.V-K ntercomparson. Symbols as defned n the text.

10 0 The measurement results are compled n Table. A cross ndcates that the partcpant dd not take part n the ntercomparson of ths lqud. ν s the knematc vscosty, ' u the relatve standard measurement uncertanty stated by each partcpant, and n the number of partcpants. The reference value (arthmetc mean value) n ν = ν () R n = as well as the uncertanty (k = 2) of ths mean value U n 2 = 2 ( ν ν R ) (2) n( n ) = and the relatve uncertanty of the mean value U ' = U / ν are calculated. The quantty R ' U can be found n the lne Reference value of Table, followed by U. The degrees of equvalence are calculated wth the ad of the followng two formulas prvately communcated by R. Davs, BIPM. The offset D n = ν ν j (3) n j= s the dfference of the vscosty obtaned by nsttute from the reference value. Equaton (3) s regarded as the workng equaton wthn the meanng of the Gude to the Expresson of Uncertanty n Measurement [5] wth the nfluence quanttes ν... ν n. For a laboratory,, whose result s used to compute ν R, the varance of the offset s u n ( D ) = 2u j + u n j= n (4) wth u =ν u, and the expanded uncertanty of the offset (k = 2): R ' U D ) = 2 u( D ). (5) ( For a laboratory,, whose result s not used to compute ν R, the varance of the offset s smply n ( D ) = 2u j u n j= u +. (6) The degrees of equvalence D and U D ) between nsttute and the reference ( value can be seen from Table.

11 The degrees of equvalence between nsttute and nsttute j are D, j =ν ν j (7) U = + (8) 2 2 ( D, j ) 4u 4u j and can be calculated from the nformaton avalable n Table. In the mddle part of Table the results for the addtonal partcpants are lsted. The relatve uncertanty of the reference value for lquds A, B and B2 s about 0,%, whereas for lqud B3 0,3% and for lqud C 0,2% are obtaned. Ths s a good result whch s comparable wth the most recent EUROMET ntercomparsons [3]. There s an ncrease n measurement uncertanty at hgher vscosty (lqud C) as well as at hgher temperatures (lqud B3). In the case of the lqud B3, t s to be noted that only sx partcpants contrbuted to the reference value. The data from Table are addtonally plotted n Fg. to Fg. 5. CCM.V-K Knematc vscosty of lqud A (20 C) ν R = 9,659 mm²/s Degrees of equvalence D and expanded uncertanty U (k = 2) D = (ν - νr) / (mm 2 /s) x Red damonds: laboratores mantanng an ndependent scale Red lnes: expanded uncertanty of the reference value -0 BNM-LNE CANNON GUM IMGC-CNR NMIJ NM-VSL NRCCRM PTB SMU UME VNIIM BEV CENAM INM(RO) IPQ NIS NPLI SIRIM Fgure : Lqud A at 20 C

12 CCM.V-K Knematc vscosty of lqud B (20 C) νr = 285,57 mm²/s Degrees of equvalence D and expanded uncertanty U (k = 2) Red damonds: laboratores mantanng an ndependent scale Red lnes: expanded uncertanty of the reference value -0 BNM-LNE CANNON GUM IMGC-CNR NMIJ NM-VSL NRCCRM PTB SMU UME VNIIM BEV CENAM INM(RO) IPQ NIS D = (ν - νr) / (mm 2 /s) NPLI Fgure 2: Lqud B at 20 C CCM.V-K Knematc vscosty of lqud B2 (40 C) νr = 394,075 mm²/s Degrees of equvalence D and expanded uncertanty U (k = 2) D = (ν - νr) / (mm 2 /s) Red damonds: laboratores mantanng an ndependent scale Red lnes: expanded uncertanty of the reference value -5 BNM-LNE CANNON GUM IMGC-CNR NMIJ NM-VSL PTB SMU UME VNIIM BEV CENAM INM(RO) IPQ NIS NPLI Fgure 3: Lqud B2 at 40 C

13 CCM.V-K Knematc vscosty of lqud B3 (00 C) νr = 39,879 mm²/s Degrees of equvalence D and expanded uncertanty U (k = 2) Red damonds: laboratores mantanng an ndependent scale Red lnes: expanded uncertanty of the reference value -5 BNM-LNE CANNON IMGC-CNR PTB UME VNIIM CENAM NPLI D = (ν - νr) / (mm 2 /s) x0 - SIRIM Fgure 4: Lqud B3 at 00 C CCM.V-K Knematc vscosty of lqud C (20 C) νr = 36587,5 mm²/s Degrees of equvalence D and expanded uncertanty U (k = 2) D = (ν - νr) / (mm 2 /s) x Red damonds: laboratores mantanng an ndependent scale Red lnes: expanded uncertanty of the reference value -0 BNM-LNE CANNON GUM IMGC-CNR NMIJ NM-VSL NRCCRM PTB SMU UME VNIIM CENAM INM(RO) NIS Fgure 5: Lqud C at 20 C

14 4 References [] ISO TR 3666: Vscosty of water (998) [2] M. R. Cannon, R. E. Mannng, J. D. Bell: The knetc energy correcton and a new vscometer Anal. Chem 32/3 (960) [3] H. Bauer, G. Klngenberg (Edtors), Report PTB-ThEx-22 (200) [4] M. R. Hoover, R. E. Mannng, R. F. Berg: Cannon Instrument Company s Vscosty Measurement Uncertantes (2002) Cannon, USA [5] Gude to the Expresson of Uncertanty n Measurement, corrected and reprnted 995, Internatonal Organzaton of Standardzaton (Geneva, Swtzerland)