The nominal boiling point of nitrogen is –196°C at one atmosphere of pressure. The defining triple point of argon is –189.3442°C. While there is a difference between the nominal boiling point of nitrogen and the argon triple point, the difference can be corrected for mathematically, and an uncertainty of less than 2 mK from the actual argon triple point is achievable.

Fluke Calibration's LN₂ Comparison Calibrators consist of a vacuum-sealed stainless steel Dewar Flask, a high-purity copper block, and a precision-fit lid. The dewar is filled with LN₂ and the copper block is suspended in it; an SPRT is inserted into the block and a calibration is performed against your own calibrated SPRT. The 7196B-4 includes four 8-mm (0.32") wells. The 7196B-13 includes five 8-mm (0.32") wells and eight 6.35-mm (0.25") wells.

Fluke Calibration's LN₂ Comparison Calibrators are neither expensive nor complicated to use. If you need supporting data or would like to discuss the theory of operation of an LN₂ Comparison Calibrator, call Fluke Calibration today. (Or come to one of our calibration training courses and we’ll show you.)