This project is the regional extension of the CCT-K7 key comparison of water triple point cells. The project will be coordinated by NMi VSL with support from co-pilot institutes CEM, INRIM, LNE-INM/CNAM, MIRS/FE-LMK, SMD and SMU.
The measurement pattern can be essentially divided into two parts:
Part 1 (see following points1.1 to 1.7) in which the link to CCT-K7 is re-established for the co-pilot participants by using the CCT-K7 transfer cells in combination with the NMi VSL transfer cells.
Part 2 (see following points 2.1 to 2.6) in which the link to CCT-K7 is established for all the non-co-pilot participants.
NMi VSL prepares a set of 6 cells of known isotopic composition (which in the following will be designated as NMi VSL transfer cells).
NMi VSL compares the set of 6 NMi VSL transfer cells with its national standard and its reference cell for the comparison (cell VSL98T094, which was used as transfer cell during CCT-K7).
One NMi VSL transfer cell is transferred to each one of the 6 co-pilots laboratories.
Each participant laboratory selects one transfer cell for the comparison. The laboratories that participated to CCT-K7 (except for PTB) adopt as transfer cell for this comparison the same cell that they used as transfer cell in CCT-K7.
The non-copilot laboratories that participated to CCT-K7 compare the selected transfer cell to their own national reference (cell or group of cells).
The non-copilot laboratories that participated to CCT-K7 deliver the selected transfer cell to the assigned co-pilot.
The copilot laboratories that participated to CCT-K7 compare the received NMi VSL transfer cell with the cell they used as transfer cell in CCT-K7 and with their national reference. The copilot laboratories that did not participate to CCT-K7 compare the following cells: the received NMi VSL transfer cell, the transfer cell of the non-copilot laboratory that participated to CCT-K7, the local transfer cell and the local national reference.
Each non-copilot laboratory that did not participate to CCT-K7 compares its selected transfer cell to its own national reference (single cell or group of cells).
Each non-co-pilot laboratory that did not participate to CCT-K7 delivers the selected transfer cell to the assigned co-pilot.
The co-pilot measures the group of cells formed by its own transfer cell, the NMi VSL transfer cell and the assigned non-co-pilot’s transfer cells and a maximum of three cells.
The co-pilots deliver the NMi VSL transfer cell back to NMi VSL and the non-copilot labs retrieve their respective transfer cells.
Each non-co-pilot participant laboratory re-compares the received cells to its national reference.
NMi VSL re-compares the NMi VSL transfer cells to its national reference.
Final Report 2011-03-20
The comparison has been completed and results are available in the KCDB.