Final report. September 2014

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Rudolf Parrish
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1 Final reort Final reort on EURAMET.M.P-S12 Bilateral Slementary omarison of the National Pressre Stanars of MI an INRIM in the Range 3 Pa to 15 kpa of Negative Gage Pressre Zeněk Krajíček 1, Mercee Bergoglio 2, Dominik Pražák 1, Stefano Pasqalin 2 Setember zech Metrology Institte (MI), Okrřní 31, 638 Brno, zech Reblic 2. Istitto Nazionale ella Ricerca Metrologica (INRIM), Straa elle acce 91, 1135 Torino, Italy - 1 -

2 Abstract This reort escribes a EURAMET bilateral slementary comarison between zech MI an Italian INRIM in low negative gage ressre in gas (nitrogen), enote as EURAMET.M.P-S12. The igital non-rotating ressre balance FPG861 manfactre by Flke/DH- Instrments, USA is normally se for gage an absolte ressres in the range from 1 Pa to 15 kpa, bt with some moifications it can be se also for the negative gage ressres in the same range. Dring the rearation of the visit of INRIM at MI for the last comarison within the framework of EURAMET.M.P-K4.21, it was agree to erform also an aitional comarison in the range from 3 Pa to 15 kpa of negative gage ressre. The measrements were erforme in October 212. Both instittes sccessflly rove their eqivalence in all the teste oints in the range from 3 Pa to 15 kpa of negative gage ressre in a comarison which ha been niqe so far

3 ontent 1. Introction 4 2. Stanar of MI 5 3. Stanar of INRIM 5 4. Procere of the comarison 5 5. Evalation of the comarison 7 6. Reslts of the comarison 8 7. onclsion 9 8. References 9-3 -

4 1. Introction The igital non-rotating ressre balance FPG861 manfactre by Flke/DH- Instrments is base on a 1 cm 2 non-rotating tngsten-carbie iston-cyliner with a conical ga [1]. It is normally se for gage an absolte ressres in the range from 1 Pa to 15 kpa, bt with some moifications it can be se also for the negative gage ressres in the same range. However, measrement of the negative gage ressres has been a neglecte branch of the rimary metrology with the lack of the international interlaboratory comarisons [2]. Recently an intercomarison (EURAMET.M.P-S8) was erforme [3] an two others are being in rogress (EURAMET.M.P-S9, SIM.M.P-S5), bt none of these covers the negative gage ressres lower than 1 kpa. In the year 211, MI got exerience with tilizing FPG 861 in the negative gage ressre moe. Dring the rearation of the visit of INRIM at MI for the last comarison within the framework of EURAMET.M.P-K4.21, it was agree to erform also an aitional comarison in the range from 3 Pa to 15 kpa of negative gage ressre. It was registere as a slementary comarison (EURAMET.M.P-S12) an it is aime to verify the eqivalence of the national low negative gage ressre stanars of zech Reblic an Italy. The staff of INRIM volnteere to transort their FPG861 to MI, Brno, where the measrements were erforme from October 4-5, 212. Each stanar was evalate in its own institte, so that they were consiere ineenent. The fact that both stanars met in one laboratory gave the ossibility to comare the two systems withot any transfer stanar. A caacitance iahragm gage (DG), however, ha to be se to searate them. In this case a igital ressre controller Flke/DH-Instrments PP3-2K was se for ressre reglation of both FPGs instea of Flke/DH-Instrments Very Low Pressre ontrollers (VLPs) which is otherwise normally tilize. The Technical Protocol of this comarison was reare on the basis of Technical Protocol of EURAMET.M.P-K4.21 an in accorance with the Gielines for IPM Key omarisons. The nominal negative gage ressre oints were 3 Pa, 1 kpa, 3 kpa, 1 kpa an 15 kpa. Measrements were erforme in two cycles in two ifferent ays. Nitrogen was se as ressre transmitting meim

5 2. Stanar of MI The stanar of MI was a igital non-rotating iston gage FPG861, ientifie by serial nmber 17, see [4]. The effective area was evalate by the measrement of the iston-cyliner geometry an valiate by the cross-floating techniqes. An intercomarison with the Slovak SMU was erforme in 22, with the Finnish MIKES in 23, EUROMET.M.P-S2 in 26 an EURAMET.M.P-K4.21 is still rnning. The ncertainty (for k = 1) of this stanar eqals =.1 Pa , where is in ascal. In this case a DH-Instrments PP3-2K, ientifie by serial nmber 225, was se as a ressre reglator instea of a VLP. (When measring in negative moe, the VLPs of both FPGs were connecte to their FPGs only electrically bt nematically isconnecte.) A DG (MKS Baratron of tye 698A1TRA, ientifie by serial nmber 43657, with control nit of tye 27, ientifie by serial nmber 42869) with a set of valves serve as a zero inicator an as a searator between both stanars. This instrment is caable of reaing via P with installe FPG TOOLS. It was rovie by MI with a calibration for both ls an mins inications with an emhasis on the range aron zero. Its mltilicative correction factor DG = (1.1 ±.9), for k = 1 (consisting of the calibration ncertainty an the long-term stability). However, ring the measrements the DG inication was ket as near to zero as ossible. 3. Stanar of INRIM The stanar of INRIM was a igital non-rotating iston gage FPG861 manfactre by DH-Instrments, ientifie by serial nmber 132. Its ncertainty (for k = 1) was evalate eqal to I =.1 Pa , where is in ascal. The effective area was evalate by the measrement of the iston-cyliner geometry an valiate by the cross-floating techniqes in gage moe. Both vales agree within the ncertainties. 4. Procere of the comarison The nominal negative gage ressre oints n were 3 Pa, 1 kpa, 3 kpa, 1 kpa an 15 kpa. Measrements were mae in two cycles. Each cycle was erforme at a ifferent ay. The ressre transmitting meim was ry nitrogen (ry is the gas entering FPG stan, however the FPG ajsts hmiity of the gas to aroximately 5 % via its internal reservoir of water)

6 Both stanars were locate close to each other to kee the ressre line between the two instrments as short as ossible. There was no height ifference between the reference levels of both stanars within an ncertainty of abot 1 mm. (Pressre ncertainty of small ressre hea is incle in the eclare ncertainty of the FPG of the MI.) Both reference orts (bt in the negative gage moe the er ort serves as the reference ort) of both stanars were flly oen to atmoshere. The VLPs of both FPGs were connecte to their FPGs only electrically bt isconnecte nematically an the setting maximm range was chosen in the software mens of both FPGs. The comarison measrements were erforme sing 1 torr DG as a zero inicator. A byass line with a valve connecte the both sies of the zero ressre inicator to control its zero ressre reaing. The DG was not heate ring the measrements. The DG was connecte to both stanars via tbings (bellows) that were as similar to each other as mch as ossible concerning their iameters an volmes. The by-ass closing valve of the DG i not ince large changes of ressre. Before the start of the comarison measrements both stanars were zeroe an then calibrate internally. (heck of the internal calibration was reeate every for hors.) Then the by-asses of the FPGs were close by a software comman an the reglation by PP3 (connecte to the low ressre ort) was activate. Then both instrments were zeroe again an the zero was checke an rea. Then the isolation valve between both stanars was close (bt with DG by-ass valve remaining oen). Only after this, the target nominal ressre was set by an FPG that was not connecte to the DG at the moment. Then the generate target ressre was set by the other FPG (filling also DG). After stabilization, the zero of the DG was rea by the oen by-ass valve. Then the by-ass valve was close an the isolating valve oen. After stabilization of reaing, 5 sccessive reaings were taken by averaging otts of FPGs an DG ring at least 1 min. After measring a oint, a check of the DG zero rift (if sfficiently stable this checking nees not to be erforme after every oint) an check of the zero rifts of both stanars were one. The reslts were correcte for these rifts

7 5. Evalation of the comarison The ressre efine from the FPG of MI (correcte for its zero rift) in combination with the DG reaing was se to reict the reaing insie the FPG of INRIM. This reicte vale was comare to the vale I evalate from the FPG of reicte I INRIM itself (also correcte for its zero rift). If enotes the ressre as etermine by the stanar of MI an DG the ressre reaing of the DG, the reicte ressre in the stanar of INRIM is given by: I DG ( ) 2 DG reicte, (1) where zero reaing of the DG before the measrement, zero reaing of the DG after the measrement, DG calibration factor of the DG. For each measrement i (i = 1 5) on ay j (j = 1,2) at the efine target ressre the ifference ij between the two systems is calclate as: ij Iij Iij reicte. (2) For each nominal ressre a single vale of is calclate by taking the mean of all measrements of the two ays: ij. (3) 1 j 1 i 1 The ncertainty DG. The ncertainties of of is etermine by the ncertainties of, I an, DG (enote as, I an liste in Sections 2 an 3. Since the sensitivity coefficient for I, DG DG,,, ) were alreay varie significantly DG at a ressre oint, we took the maximm vale. Becase the DG was calibrate by the FPG of MI, we assme a fll correlation between an DG. The ncertainties of DG,,, are inaccrate by the scatter an short term instabilities which are reveale in the scatter of reeat calibrations. Therefore these ncertainties are being consiere in the exerimental stanar eviation of the mean of. Since n = 1 measrements were taken with an effective egree of freeom of 9, the sqare of the - 7 -

8 stanar eviation of the mean of the reeate measrements 1 n 3 n, as sggeste by Kacker an Jones [5]. s ij was mltilie by Hence the total ncertainty of for each nominal ressre is then given by: s n 1 I DG. (4) 2 DG ij n 3 6. Reslts of the comarison Tab. 1 gives the smmarize reslts for for each nominal ressre n, the exerimental stanar eviation of the mean of the ij, the remaining sorces of ncertainty an the total ncertainty of. n s DG I Pa Pa Pa Pa Pa Pa Pa 3 -,37,8,3,14,15,22 1 -,1,4,3,24,25,35 3,45,1,3,52,55,76 1,275,6,3,15,16,22 15,432,9,3,22,235,322 Tab. 1: Reslts of the comarison an ncertainty bget. Tab. 2 gives the overview of for each nominal ressre n, the ncertainties eclare by both articiants, the total exane (k = 2) ncertainty U of an the egrees of eqivalence. Fig. 1 a 2 give a grahical illstration of this. It can be seen from Tab. 2 that all E n (normalize error) vales were always within ±1, so that the fll eqivalence of both stanars was rove. n U U U I E n Pa Pa Pa Pa Pa - 3 -,37,44,28,29 -,84 1 -,1,7,48,5 -,14 3,45,152,14,11,3 1,275,439,3,32,63 15,432,645,44,47,67 Tab. 2: Reslts of the comarison, relevant ncertainties an eqivalence

9 Fig. 1: Reslts of the comarison an relevant ncertainties. iamons, line, U I green line, U black line. U ble 1,1 1,,9,8,7,6,5 /Pa,4,3,2,1, ,1 -,2 -,3 P /Pa Fig. 2: Reslts of the comarison an relevant ncertainties. iamons, U error bars

10 7. onclsions Both instittes sccessflly rove their eqivalence in the range from 3 Pa to 15 kpa of negative gage ressre in a comarison which ha been niqe so far. 8. References [1] DELAJOUD, P., GIRARD, M.: Vakm in Forschng n Praxis 15 (23), [2] TESAŘ, J., KRAJÍČEK, Z., PRAŽÁK, D., STANĚK, F.: Materiali in Tehnologie 43 (29), [3] RANTANEN, M., SAXHOLM, S., ALTINTAS, A., PAVIS, R., PETERSON, G.: Metrologia 47 (21), Tech. Sl. 77. [4] TESAR, J., REPA, P., PRAZAK, D., KRAJIEK, Z., PEKSA, L.: Vacm.76 (24), [5] KAKER, R., JONES, A.: Metrologia 4 (23),

COOMET Project 507/BY/10. Supplementary COMPARISON OF LENGTH STANDARDS FOR MEASURING GEAR PARAMETERS COOMET.L- S10. Final Report

COOMET Project 507/BY/10. Supplementary COMPARISON OF LENGTH STANDARDS FOR MEASURING GEAR PARAMETERS COOMET.L- S10. Final Report ЕВРО-АЗИАТСКОЕ СОТРУДНИЧЕСТВО ГОСУДАРСТВЕННЫХ МЕТРОЛОГИЧЕСКИХ УЧРЕЖДЕНИЙ (KOOMET EURO-ASIAN COOPERATION OF NATIONAL METROLOGICAL INSTITUTIONS (COOMET Janary 2012 COOMET Proect 507/BY/10 Spplementary COMPARISON