CCT-K7, EUROMET.T-K7, COOMET.T-K7, EURAMET.T-K7.1, EURAMET.T-K7.2, EURAMET.T-K7.3, APMP.T-K7.1 and EURAMET.T-K7.4

MEASURAND   Temperature of triple point of water

NOMINAL VALUE 273.16 K

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence, both expressed in μK.

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CCT-K7, EUROMET.T-K7, COOMET.T-K7, EURAMET.T-K7.1, EURAMET.T-K7.2, EURAMET.T-K7.3, APMP.T-K7.1 and EURAMET.T-K7.4

MEASURAND   Temperature of triple point of water

NOMINAL VALUE 273.16 K

Degrees of equivalence represented by D_i = (x_i - x_R) and its expanded uncertainty U_i at a 95 % level of confidence, both expressed in μK.

CCT-K7, EUROMET.T-K7, COOMET.T-K7, EURAMET.T-K7.1, EURAMET.T-K7.2, EURAMET.T-K7.3, APMP.T-K7.1 and EURAMET.T-K7.4

MEASURAND   Temperature of triple point of water

NOMINAL VALUE 273.16 K

The key comparison reference value, x_R, is calculated as the arithmetic mean of the results, x_i, from all participants, including some laboratories who made corrections for the influence of chemical impurities and isotopic composition, and some who did not.
x_R = 22 µK (expressed as the difference from the BIPM value).
The uncertainty of x_R, u_R, is calculated as the standard deviation of the mean of the data set. u_R = 11 µK.
Because the distribution of the pooled data is multimodal, care should be taken when using this quantity for calculating confidence intervals.

The degree of equivalence of laboratory i with respect to the key comparison reference value is given by a pair of terms:
D_i = (x_i - x_R) and its expanded uncertainty U_i (k = 2), both expressed in µK.
The uncertainty includes the participant's uncertainty, the comparison uncertainty and the uncertainty of the key comparison reference value.

The degree of equivalence between two laboratories i and j is given by a pair of terms:
D_ij = (D_i - D_j) = (x_i - x_j) and its expanded uncertainty U_ij (k = 2), both expressed in µK. The uncertainty includes both participants' uncertainties and twice the comparison uncertainty.

EUROMET.T-K7

The EUROMET reference value referred to the NMi-VSL reference cell (VSL-094),
x_{R EUR}, and its standard uncertainty, u_{R EUR}, are computed from the weighted mean of the individual results, with the exclusion of the CMI and GUM results, as explained in Section 7.1 on page 29 of the EUROMET.T-K7 Final Report:
x_{R EUR} = 15.6 µK, and u_{R EUR} = 10.5 µK

The degree of equivalence of laboratory i, participant in EUROMET.T-K7, with respect to the EUROMET reference value is given by a pair of terms: D_iEUR = x_iEUR - x_{R EUR}, and its expanded uncertainty U_iEUR (k = 2), both expressed in µK.

Linking EUROMET.T-K7 to CCT-K7

The linkage process of EUROMET.T-K7 results to those of CCT-K7 is explained in Section 7.3 on page 36 of the EUROMET.T-K7 Final Report. It is based on the common participation of CEM, IPQ, LNE-INM, NMi-VSL, and SMU in both comparisons.

The degree of equivalence of laboratory i, participant in EUROMET.T-K7, with respect to the CCT-K7 key comparison reference value is given by a pair of terms:
D_i = D_iEUR + d_LINK with d_LINK = 64.7 µK, and its expanded uncertainty (k = 2)
U_i = 2[(U_iEUR/2)² + (u_LINK)²]^1/2, with u_LINK = 19.7 µK, both expressed in µK.

Pair-wise degrees of equivalence are computed inside EUROMET (see Section 7.2 on page 30 of the EUROMET.T-K7 Final Report).

Linking EURAMET.T-K7.2 to CCT-K7

The degree of equivalence of INTiBS relative to the CCT-K7 key comparison reference value is computed through the common participation of VSL in EURAMET.T-K7.2 and EUROMET.T-K7 (see Section 6 of the EURAMET.T-K7.2 Final Report).

Linking EURAMET.T-K7.3 to CCT-K7

The degree of equivalence of GUM relative to the CCT-K7 key comparison reference value is computed through the common participation of VSL in EURAMET.T-K7.3 and EUROMET.T-K7 (see Sections 6 and 7 of the EURAMET.T-K7.3 Final Report).

Linking EURAMET.T-K7.1 to CCT-K7

New degrees of equivalence relative to the CCT-K7 key comparison reference value are obtained in EURAMET.T-K7.1 for SMU and CMI, through the common participation of SMU in EURAMET.T-K7.1 and EUROMET.T-K7, taking into account the change of national reference cell at SMU since the completion of EUROMET.T-K7.

Linking COOMET.T-K7.3 to CCT-K7

The linkage process of COOMET.T-K7 results to those of CCT-K7 is explained in Section 6 of the COOMET.T-K7 Final Report. It is based on the common participation of VNIIM in both comparisons

The degree of equivalence of laboratory i, participant in COOMET.T-K7, with respect to the CCT-K7 reference value is given by a pair of terms: D_i, and its expanded uncertainty (k = 2) U_i, both expressed in µK.

No pair-wise degrees of equivalence are computed inside COOMET.T-K7.

Linking APMP.T-K7.1 to CCT-K7

The degree of equivalence of VMI-STAMEQ relative to the CCT-K7 key comparison reference value is computed through the common participation of NMIJ in APMP.T-K7 and CCT-K7 (see Section 8 of the APMP.T-K7.1 Final Report).

Linking EURAMET.T-K7.4 to CCT-K7

UME provides the link between the key comparison CCT-K7 and EURAMET.T-K7.4, having participated in both comparisons. The linking process is described in Section 9 of the EURAMET.T-K7.4 Final report.

CCT-K7, EUROMET.T-K7, COOMET.T-K7, EURAMET.T-K7.1, EURAMET.T-K7.2, EURAMET.T-K7.3, APMP.T-K7.1 and EURAMET.T-K7.4

MEASURAND   Temperature of triple point of water

NOMINAL VALUE 273.16 K

CCT-K7

x_i : temperature difference between the national reference of laboratory i and the BIPM reference, x_i = T(Lab i) - T(BIPM), where T is the temperature
u_i : combined standard uncertainty of x_i

EUROMET.T-K7

x_iEUR : temperature difference between the national reference of laboratory i and the NMi-VSL reference cell (VSL-094), x_i = T(Lab i) - T(VSL-094), where T is the temperature
u_iEUR : combined standard uncertainty of x_iEUR

COOMET.T-K7

The comparison was performed in three stages: 1) each participating laboratory carried out comparisons of the transfer cell with its national standard cell in local conditions; 2) the transfer cells were forwarded together with measurement results to BelGIM, where they were compared with the standard BelGIM cell using its laboratory equipment; and 3) the transfer cells were sent back to laboratories, where they were compared again to the national standard cells in order to determine the stability of the transfer cells.
The measurement results of the participating laboratories are given in section 2, 3, and 4 of the COOMET.T-K7 Final Report.

EURAMET.T-K7.2

The measurement results of this bilateral key comparison between VSL (The Netherlands) and INTiBS (Poland), carried out in 2010, are summarized in Sections 3 and 4, on pages 5 and 6 of the EURAMET.T-K7.2 Final Report.
They lead to the following numbers:
T^INTiBS _{Nat. Ref.} - T^VSL _{Nat. Ref.} = 2.9 µK and associated combined standard uncertainty (k = 1) u = 46 µK, where "Nat. Ref." stands for "National Reference".

EURAMET.T-K7.3

The measurement results of this bilateral key comparison between VSL (The Netherlands) and GUM (Poland), carried out in 2011, are summarized in Sections 3 and 4, on pages 5 and 6 of the EURAMET.T-K7.3 Final Report.
They lead to the following numbers:
T^GUM _{Nat. Ref.} - T^VSL _{Nat. Ref.} = 11.5 µK and associated combined standard uncertainty (k = 1) u = 60 µK, where "Nat. Ref." stands for "National Reference".

EURAMET.T-K7.1

The measurement results of this bilateral key comparison between CMI (Czech Republic) and SMU (Slovakia), carried out in 2009, are summarized in Sections 2 and 3 of the EURAMET.T-K7.1 Final Report.
It should be noted that SMU replaced its national reference cell with a cell with known isotopic composition after completion of key comparison EUROMET.T-K7.

APMP.T-K7.1

The measurement results of this bilateral key comparison between VMI-STAMEQ (Viet Nam) and NMIJ (Japan), carried out in 2014 - 2015, are summarized in Sections 3 to 6 of the APMP.T-K7.1 Final Report.
They lead to the following numbers:
T^VMI-STAMEQ _{Nat. Ref.} - T^NMIJ _{Nat. Ref.} = -19.9 µK and associated combined standard uncertainty (k = 1) u = 46.3 µK, where "Nat. Ref." stands for "National Reference".

EURAMET.T-K7.4

The measurement results are summarized in Section 8 of the EURAMET.T-K7.4 Final report.