6th CCM International Conference on Pressure and Vacuum Metrology - 5th International Conference IMEKO TC16 May 8 − 10, 2017. Pereira, Colombia

SIM KEY COMPARISON IN PNEUMATIC GAUGE PRESSURE FOR
HIGH ACCURACY PRESSURE BALANCE UP TO 120 kPa, SIM.M.P-K6
1J. C. Torres-Guzman, 1J. Aranzolo, 2D. A. Olson, 3J. Forastieri, 4A. Solano, 5C. Neira,
6P. R. G. Couto, 7L. De La Cruz, 8J. Palma, 9S. Garcia 1CENAM, Mexico. 2NIST, USA. 3INTI, Argentina. 4LACOMET, Costa Rica. 5INM, Colombia. 6INMETRO, Brazil. 7INACAL, Peru. 8ENAER, Chile. 9CENAMEP, Panama. Email of corresponding author: jorge.torres@cenam.mx1
Abstract − This report describes the results of a pneumatic pressure standards key comparison among nine SIM National Metrology Institutes in order to determine their degree of equivalence in the pressure range from 10 kPa to 120 kPa in gauge mode. The pilot laboratory was the Centro Nacional de Metrología (CENAM, Mexico). All participating institutes used pneumatic pressure balances as their pressure standard. The transfer standard was a complete system including a pressure balance with a free-deformational piston-cylinder assembly and a set of masses. Eleven participants completed their measurements, although, only nine laboratories reported the pressure-dependent effective areas of the transfer standard at specified pressures with the associated uncertainties. NRC/Canada and BSJ/Jamaica withdrew the comparison by not sending their measurements. The results of the eight laboratories that sent their results were linked to the CCM.P-K6 comparison through the reference values provided by NIST, USA. The degrees of equivalence were evaluated by the relative deviations of the participants' results from those obtained by NIST. The results of six participating NMIs agree with the NIST reference values within their expanded uncertainties (k=2) in the entire pressure range from 10 kPa to 120.
Keywords: Comparison, pressure balances.
1. INTRODUCTION.
This comparison aimed to obtain the equivalence statements into SIM region derived from CCM key Comparison CCM.P-K6, in the range from 10 kPa to 120 kPa, in pneumatic gauge pressure. This comparison will provide the means to the laboratories to support their uncertainty statements given in their CMC Tables. The number of participants was eleven, three NMI from NORAMET, two from CAMET, one from CARIMET, two from ANDIMET and three from SURAMET. NRC/Canada and BSJ/Jamaica withdrew the comparison by not sending their measurements. The Centro Nacional de Metrología (CENAM), Mexico, was the pilot laboratory in this comparison. The Technical Protocol, prepared in accordance with the Guidelines for CIPM Key Comparisons, specified the procedure followed for the comparison.
2. MEASUREMENTS RESULTS
Table 1 and graph 1 present the results for A0 and its corresponding expanded uncertainty for each participating NMI, m2. In table 1, laboratories in italics did not calculated A0 (INMETRO, INM and CENAMEP). In order to compare results CENAM made the calculations by means of the lineal regression method. INMETRO used 23 °C as reference temperature. In order to better compared, results for this laboratory, a temperature correction was used to transfer their results to 20 °C reference temperature, as outlined in the Comparison Protocol. Table 1. TS A0 and its corresponding expanded uncertainty as obtained by each NMI, m2.
A0 / m2 UA0 / m2 b / 1/Pa Ub / 1/Pa
CENAM 9.805 18 E-04 1.2E-08 6.1E-11 2.7E-11
INTI 9.805 32 E-04 3.8E-08 -2.0E-10 9.7E-11
NIST 9.805 06 E-04 2.8E-08 0.0E+00 0.0E+00
INMETRO 9.805 07 E-04 4.8E-08 -9.0E-11 1.2E-10
INM 9.805 19 E-04 2.4E-08 5.5E-12 1.5E-11
INACAL 9.805 19 E-04 1.9E-08 -2.4E-14 3.2E-11
ENAER 9.805 07 E-04 1.9E-08 5.7E-11 1.9E-11
LACOMET 9.805 43 E-04 2.4E-08 -1.0E-07 4.8E-08
CENAMEP AIP 9.814 72 E-04 7.9E-07 2.4E-13 1.1E-08

Graph 1. TS A0 and its corresponding expanded uncertainty as obtained by each NMI, m2. For clarity, CENAMEP is not included.
3. EVALUATION OF RESULTS AND
CONCLUSIONS For evaluation of the NMIs performance the normalized error equation (En) criteria was applied to their TS effective area results. Table 2 and graph 2 present the results of the normalized error equation. In this SIM comparison, 11 laboratories participated. From those, two did not sent their measurement results (NRC/Canada and BSJ/ Jamaica). From the eight laboratories which sent their results, six laboratories have compatibility of their results with the references values provided by NIST, as it can be seen in graph 2 as well as in table 2. One laboratory (LACOMET) is just out of the compatibility zone (between 1 and 1.5) and one laboratory (CENAMEP) has no compatibility with the reference values or with those results of the other participating laboratories. Table 2. Normalized error equation values of participating NMIs with respect to the reference (NIST) for Area (A0).
NMI 10 kPa 20 kPa 30 kPa 40 kPa 50 kPa 60 kPa 70 kPa 80 kPa 90 kPa 100 kPa 110 kPa 120 kPa INTI 0.79 0.50 0.51 0.41 0.33 0.37 0.30 0.23 0.26 0.15 0.27 0.25 CENAM 0.38 0.45 0.59 0.51 0.69 0.98 0.87 0.88 0.85 0.92 0.83 0.89 INMETRO 0.58 -0.04 -0.15 -0.23 -0.25 -0.16 -0.09 -0.17 -0.10 -0.06 -0.13 -0.13 ENAER --- 0.04 0.13 0.10 0.16 0.31 0.31 0.35 0.25 0.32 0.32 0.34 INM 0.32 0.49 0.60 0.54 0.53 0.60 0.61 0.59 0.54 0.59 0.59 0.62 INACAL 0.45 0.59 0.49 0.41 0.49 0.52 0.51 0.51 0.48 0.55 0.55 0.54 LACOMET 1.3 1.1 1.3 1.2 1.5 1.40 1.3 1.3 1.3 1.2 1.2 1.2 CENAMEP 98 28 29 34 43 56 64 730 81 94 103 112
Graph 2. Participating laboratories normalized error equation results with respect to NIST’s reference values. For clarity, CENAMEP is not included.
REFERENCES
Sabuga W., Bergoglio M., Rabault T., Waller B., Torres J., Olson D., Agarwal A., Kobata T., Bandyopadhyay A., [PTB, IMGC, BNM-LNE, NPL, CENAM, NIST, INMS/NRC, NMIJ/AIST, NPLI], “Final Report on Key Comparison CCM.P-K7 in the range from 10 MPa to 100 MPa of hydraulic gauge pressure”. Metrologia, 2005, 42, Tech. Suppl., 07005.
9,804 60 E-049,804 80 E-049,805 00 E-049,805 20 E-049,805 40 E-049,805 60 E-04
9,805 80 E-04
CENAM INTI NIST INMETRO INM INACAL ENAER LACOMETArea A 0±Expanded uncert
anity /m2 A0
-0,500,000,501,00
1,50
10 kPa 20 kPa 30 kPa 40 kPa 50 kPa 60 kPa 70 kPa 80 kPa 90 kPa 100 kPa 110 kPa 120 kPaINTI CENAM INMETRO ENAER INM INACAL LACOMET