Can a -20°C reference point be established in a laboratory?

摘要

When measuring temperature, an ice point is used as a zero reference point. Using an ice point, we can monitor our reference standard's drift in a laboratory. An ice point is stable and can be made up exactly to read the same temperature using the same method every time. An ice point temperature is homogeneous from top to bottom. By mixing saved ice and salt we can make a -20°C point. How accurate is a -20°C ice and salt mixture? Can we use the -20°C point as a reference point as well or to calibrate other temperature equipment? The question that we must ask ourselves is: How stable is a -20°C ice salt mixture? How accurate is a -20°C ice salt mixture? How repeatable is a -20°C ice salt mixture? Is the -20°C point also homogeneous? This paper discussed the research and development conducted by the laboratory and presents some interesting conclusions.