This is an excerpt from the November/December 2013 issue of InTech magazine by David K. Porter, P.E., is the division vice president, Crystal business manager at AMETEK. To read the full article, please see the link at the bottom of this post.

Within the pressure measurement industry, relentless innovation has become the norm. New technology continually supplants the old. In other technology spheres, PCs pushed aside typewriters. Cell phones drove out telephones. And today, reference recorders are shaking up old standards in the oil and gas industry.ND-2013-Spec-section-interchange_blog

A reference recorder is a new class of instrument that is gaining ground over other common pressure instruments. Chart recorders, deadweight testers, and analog pressure gauges all brought several advantages in their time. Increasingly, reference recorders replace all three with a single instrument.

What is a reference recorder?
Reference recorders unify the recording capability of a chart recorder, the high accuracy of a deadweight tester, and the continuous measurements of a pressure gauge into one tool that is easier to use and less expensive.

On their own, none of these features are unique, but when you put them all in the same device that reduces cost, it is something really useful. These reference recorders are effective for both laboratory and field applications. While data logging devices are nothing new, improved microprocessors allow today’s reference recorders to read and record faster and more accurately than ever.

Reference recorders detect readings from modules, which may read pressure, temperature, current, or voltage, and store the data in their digital memory. These modules are usually interchangeable, and recorders generally accept two inputs at a time. In addition to their compact size, reference recorders offer several improvements to bulky chart recorders.

Improving on a chart recorder
Chart recorders, originally patented in 1915, produce a graph on a moving paper chart. They rely on ink pens mounted on mechanical arms, which pivot in response to pressure. Their primary advantage is their ability to record for extended periods in remote locations. Chart recorders may be battery powered or entirely mechanical (requiring no external power), allowing them to operate in hazardous locations.


Any PC can download the digital data from a reference recorder.

An experienced user may provide preliminary analysis of the output from a chart recorder in the field. However, communicating or storing this data electronically becomes possible only after a technician enters or scans the chart into a computer. This process typically takes several days. Chart recorders usually claim an accuracy ranging from 0.25 percent to 1 percent of span, but that figure depends on changes in ambient temperature and on the thickness of its pens-which can cause an additional error up to 1 percent of the recorded reading. Chart recorders are also susceptible to additional errors caused by overpressure and can easily be damaged if dropped.

By contrast, a reference recorder exports digital data in a familiar spreadsheet that can be easily shared and understood by multiple users. Accuracy remains consistent with temperature changes, is protected from high overpressure events, and is not affected if the gauge is dropped. Despite being battery powered, reference recorders are also rated intrinsically safe for use in hazardous locations.

New regulations in many industries require that safety tests be documented in an electronic format. Some even require that the files produced are in a tamperproof, secure file format. Reference recorders can save the digital data in a signed pdf file, which produces read-only files that cannot be manipulated.

To read the full article on reference recorders, click here.

About the Author
David K PorterDavid K. Porter, P.E., is the division vice president, Crystal business manager at AMETEK. He has more than 25 years of experience; the last 13 years were spent in the test and measurement field developing rugged, highly accurate, and easy-to-use instruments. He has a degree in mechanical engineering from California Polytechnic State University, San Luis Obispo, where he is still active on the Industry Advisory Board.

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