Data loggers vs chart recorders: what’s the difference?

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Environmental monitoring equipment has evolved considerably over the years. Technology has paved the way to the creation of new, smaller and more accurate means to track and record conditions such as temperature. A simple comparison between the two different types of recording devices puts data loggers at the high-tech end of the scale as the newer version of the old school chart recorder. Before we dig deeper into comparing the differences, let’s look at what these devices are meant to do.

What They Are – What They Do

Data loggers and chart recorders do precisely what their name implies. They log or record different pieces of information. That information is stored for later reference. In the healthcare industry, these devices are used primarily to “watch” temperature levels. Medications such as vaccines require temperature-controlled storage and a data logger or chart recorder can provide readings of the temperature at specific intervals. The purpose of keeping track of the temperature in this kind of application is to prevent spoilage of the medication. In other applications, such as in an industrial factory or food processing plant, temperature readings recorded at regular intervals assist in maintaining compliance.

Section 1: Chart Recorders - History

Chart recorders date back to 1838 when one was incorporated into the design of a dynamometer car created by Charles Babbage. William Henry Bristol received a patent in September 1888 for a “pressure indicator and recorder” and started manufacturing these devices the following year. In March 2006 the Bristol Manufacturing Company was bought out by the Emerson Electric Company. That company continues to manufacture various electro-mechanical chart recorders, plus other instrumentation, measurement and control products. The first chart recorder made for environmental monitoring received a patent in 1915. It was designed by American inventor J. C. Stevens.

Section 2: Data Loggers – History

Data loggers are relatively new; they started to appear in the early 1990s. They are electronic devices that automatically monitor and record different environmental conditions over time. They can be set to “sample” or take measurements at regular intervals and then store that data on an onboard microprocessor. As data loggers evolved with technology, wireless models were developed that can be accessed by a smartphone with an app. Data can then be reviewed and analyzed. The data collected can also be downloaded to a computer for storage and further review. The accuracy of a data logger far exceeds that of a chart recorder although both are still used.

The Difference: Size

Both data loggers and chart recorders are small enough to be portable. Chart recorders are slightly bulkier due to the size of their components. The average chart recorder contains a motor to rotate the chart and a mechanical sensor element as well as a circular chart holder for charts that range in diameter from three to eight inches. A data logger contains a microprocessor, a sensor chip or a detachable probe all of which are smaller than the chart recorder components.

The Difference: Ease of Use

Both the data logger and the chart recorder require just minutes to set up and start recording. The main difference here is that you can get an instant view of readings just by glancing at the circular chart being marked by the chart recorder. Data loggers require downloading of information.  With apps and new software being developed, data can be fed directly to your viewing device and displayed in chart form. This is not possible with all data loggers, however.

The Difference: Flexibility of Use

Chart recorders give you one thing: a chart. It may be a tad on the basic side, but it still shows recorded temperatures on an ongoing chart that can be easily tracked. Although it may take some time to download the information recorded by a data logger for review, with various types of industry-specific software you will be able to create charts, feed data directly to websites, upload it to FTP storage sites to be shared with other users and so much more, according to Dickson Data.

The Difference: Accuracy

The toughest test a measurement instrument must pass is how well it does the job of calculating the data it is measuring. Did you get all of that? Chart recorders were adequate for the most part but the paper chart that is used is considered low resolution. This is the main issue regarding accuracy with this type of device. Plus, chart recorders are slow to react to temperature change which can be a huge concern if you are using a chart recorder for that purpose. Data loggers have a higher resolution because temperature readings are recorded digitally and have an accuracy of 0.1F.

The Difference: Cost

Generally speaking, the price of a basic data logger or chart recorder will be in the neighborhood of $200 to $300, depending on several factors such as the specifications and features of the device. Costs can go up to $1,000. Chart recorders cost more to operate than data recorders because they require high maintenance due to the constant need for paper. Data loggers record their data digitally and store it on a microprocessor for downloading at a later time. In other words, no paper.

The Difference: Maintenance

We’ve already referred to chart recorders as being high maintenance. That’s because they contain mechanical components that, over time, shift in accuracy and require periodic recalibration to keep on track. Pens and charts require regular changing, data loss can happen when a pen or chart is being replaced. Data loggers are electronic so there are no moving parts. Sensors can be replaced if required, requiring much less fuss when compared to a chart recorder.

In Conclusion

Chart recorders are very good measurement instruments, however, data loggers are far better. Not only do they cost less to operate but they are also easier to use, provide greater flexibility and are far more accurate than a chart recorder. The comparison is much like putting old technology next to new technology. Both serve a purpose, both have many benefits but new tech is better than old tech.