You Isotech 461 Simple Liquid Nitrogen Apparatus

The Isotech 461 is a cheaper alternative to the ITL M 18205. This model is a simple device open to the atmosphere consisting of a stainless steel Dewar flask filled with liquid nitrogen, an insulating layer containing a metal levelling block and a thermometer holder. A split insulated lid reduces evaporation and makes it easier to add liquid nitrogen. From time to time extra liquid nitrogen has to be add, approximately every 30 minutes, to keep the Dewar flask full.

The Dewar flask has an inner diameter of 100 mm and an inner diameter of 280 mm. The standard equalisation block houses four SPRTs or industrial thermometers with a diameter of up to 8 mm, ensuring ±0.002°C temperature uniformity.


A standard calibrated SPRT is placed in the equalization block together with the sensors to be calibrated. The whole may be in equilibrium. The level is checked and nitrogen added if necessary and measurements are taken 10 minutes later. A comprehensive manual accompanies the device, including an article by Henry E. Sostmann on the corrections needed to convert the calibration to the ITS90 value of the Argon Triple Point.


The Isotech 461 has access to the air and will slowly condense until it reaches boiling point. This is important because a calibrated SPRT serves as a reference. Simultaneous ratios of SPRT and unknown thermometers will record, using a bridge like the Isotech microK.

You can order the liquid nitrogen separately.

Open the datasheet for detailed specifications of this product.

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