A PRECISION OXYGEN POINT CALIBRATION BATH

Abstract

The usual form of oxygen point calibration bath has been modified in a simple manner to give better than an order of magnitude greater temperature stability. Tests have demonstrated that the bath can be used to transfer oxygen point calibrations from one platinum resistance thermometer to another with a reproducibility of 10⁻⁴ °C average deviation. A method for simplifying the calculation of the oxygen point resistance and a method for removing the troublesome nitrogen impurity from industrial liquid oxygen are also given. It is suggested that any laboratory can readily equip itself with a high precision oxygen point calibration bath by using a calibrated resistance thermometer in conjunction with the bath described here.