Thermochrons / Hygrochron

Choosing the Right Thermochron for the Temperature Monitoring Application - Each Thermochron model holds unique qualities (temperature range, accuracy, resolution & logging capacity) which provides the flexibility required for a wide range of applications. However, selecting the Thermochron best suited for a specific application can be a challenging process for those new to Thermochrons. Consider the following questions will provide guidance in the selection process:

1. What is the highest and lowest temperature to be monitored in the application?

The loggers are capable of operating in a number of temperature ranges. The Thermochrons’ temperature ranges can be classified 3 general categories.
• General Purpose Applications - DS1921G (-40°C to +85°C), DS1922L (-40°C to +85°C ), DS1923 (-20 to 85°C), & DS1925L (-40 to 85°C)
• High Temperature Applications - DS1922E (15°C to +140°C) & DS1922T (0°C to +125°C)
• Specialized Mid-Range Applications - DS1921H (+15°C to +46°C) & DS1921Z (-5°C to +26°C)


2. How often will the temperature readings be collected?

The duration of the logger mission is determined the logging rate, model capacity, and resolution selected. The table below provides guidance on when the logger's memory should below full.

Model Line / Configuration	Resolution	Capacity	Duration at 30 Minute Logging Rate
DS1921	0.5°C	2048	42.6 Days
DS1922 (High Res)	0.0625°C	4096	85.3 Days
DS1922 (Low Res)	0.5°C	8192	170.6 Days
DS1923 (Low Res both Temp/Hum)	0.5°C / 0.6 %RH	4096 (Temp with Humidity)	85.33 Days
DS1923 (1 High Res and 1 Low Res)	0.0625°C / 0.6 %RH	2560 (Temp with Humidity)	53.33 Days
DS1923 (High Res both Temp/Hum)	0.0625°C / 0.04 %RH	2048 (Temp with Humidity)	42.66 Days
DS1925 (High Res)	0.0625°C	62,720	1,306.66 Days
DS1925 (Low Res)	0.5°C	125,440	2,613.33 Days

The capacity can always be increased by deploying the loggers in pairs. This it particularly useful for the DS1923 since it can be paired with a more economical DS1922L. In those cases, the DS1923 is configured to only poll humidity while the DS1922L handles the temperature logging.

3. What temperature accuracy is needed for this application?

Most Thermochrons have an accuracy of between ±0.5°C and ±1.0°C through much of their operating range. The chart below provides a visualization of the logger's accuracy over their full operating range.

With the exception of the DS1922E model, which is most often used for specialized high temperature monitoring applications, the DS1922, DS1923, and DS1925 models have an accuracy of ±0.5°C over the majority of their operating temperature range. The DS1921 models peak at an accuracy of ±1.0°C, but they do so at a lower cost.

4. Is humidity data required?

The DS1923 is currently the only iButton temperature data logger that also supports humidity logging. This data logger can be programmed to monitor both temperature & humidity simultaneously, or as a standalone temperature/humidity data logger.