Control Engineering’s Process Control Newsletter for October 2001

By Dave Harrold June 4, 2002

In this issue:

  • Misinformation can lead to poor decisions
  • What are your electronic record and signature ‘need to knows?’
  • Process NMR receives CENELEC certification
  • Rosemount introduces PPB dissolved oxygen (DO) analyzer
  • Cost effective level measurement for water and wastewater
  • Conferences, seminars, and exhibitions
  • October in Control Engineering

Misinformation can lead to poor decisions

On I recently attended a vendors user group meeting and sat in on a session about electronic records and signatures. During the session, an audience member volunteered that magnetic media (i.e., floppy disk, magnetic tape, CD-ROM, etc.) are unsuitable for long-term electronic storage. This person spoke with such passion and quoted several statistics making me think this person had studied the subject of electronic media retention thoroughly and was sharing valuable information. When this person finished speaking no one in the room challenged any of his statements or claims and I’m sure several people, including myself, left the session believing they had learned something valuable about electronic records.

On the flight home I was thinking about the entire users group meeting experience, and something about the claims of magnetic media not being suitable for long-term electronic record storage didn’t seem right, so I did some investigation. My findings are considerably different than the audience volunteer at the users group session.

Tapes can last 10-30 years

One paper I located was written in March 1995 by Dr. John W. C. Van Bogart, principle investigator of media stability of the National Media Lab.

Dr. Van Bogart and his NML colleagues have determined through extensive research and testing that high quality magnetic tape, designed for digital archives, has a life expectancy of 10 to 30 years when stored at 65 +/- 3 degrees Fahrenheit (18 degrees Celsius) and 40% +/- 5% relative humidity.

Dr. Van Bogart indicates the US government agency responsible for maintaining meteorological data transcribed 20,000 ten-year-old tape cartridges to a new media and had no unrecoverable errors. The reason listed for why this transcription effort was conducted was not because of magnetic tape deterioration but because of technology obsolescence; a problem many control engineers increasingly face as hardware and software platforms evolve every 14 to 18 months.

Jim Wheeler, an archival tape engineer with over 30 years experience, wrote a second paper in February 1995. Mr. Wheeler claimed The National Institute of Standards and Technology (previously the National Bureau of Standards), the National Media Lab, the Battelle Institute, Ampex, and Sony had performed life test on tapes and a 20-year life expectancy is considered reasonable. Mr. Wheeler added he personally had 47-year-old family tapes that he plays regularly.

CD’s can last 100 to 200 years

The audience volunteer also claimed CD-ROM’s were not suitable for long-term digital archives.

I found papers prepared by Kodak (Rochester, N.Y.) discussing how continued testing of Kodak Photo CD and Kodak Writable CD media with InfoGuard Protection System (a special recording layer coating) reveals that data stored on CDs using encoded digital formats offer life expectancy of around 200 years.

A 1995 article appearing in PC Magazine indicated digitally stored data using CD-ROMs had a life expectancy of at least one hundred years.

All this to say, the issues associated with archiving electronic data on magnetic media is really all about: * Using high quality media; * Using high quality transcribing equipment (not a $200 VCR with a $5 tape); * Following recommended media storage requirements for temperature, humidity, and handling; * Ensuring the transcribing hardware, software, and user manuals are available in the future; and * Paying attention to your information sources.

If you read or listen to and believe misinformation, no matter how convincingly presented, it can lead to your making poor recommendations and/or decisions on behalf of your company; not to mention what it does to your credibility.


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What are your electronic record and signature ‘need to knows’?

One of my upcoming assignments is an article about electronic records and signatures to meet regulatory requirements. Not just FDA regulations, but OSHA, EPA, ISO, and others.

During the past month I’ve asked several end-users and now I’m asking you, ‘What are the five most important issues you would like addressed in an article about electronic records and signatures?’

I’ll use the top five issues to solicit supplier capability/response and will report my findings.

Can’t think of five, how about one or two? Send me an email at and let me know what’s bothering you most about electronic records and signatures.

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E+Process NMR receives CENELEC certification

Foxboro, Mass.Invensys Process NMR (nuclear magnetic resonance) analyzer was recently redesigned and made suitable for Zone 1 hazardous areas and awarded the IIC T4 CENELEC certification.

NMR technology provides value to refinery and petrochemical operations by reducing product variability and ‘giveaway.’

During NMR analysis, a sample stream is passed through a precisely controlled magnetic field. The protons of the sample ‘line up’ with the homogeneous magnetic field.

To take a reading, the NMR analyzer transmits pulses of radio frequency energy into the stream, deflecting the protons from their aligned axis. The amount of deflection and subsequent recovery time varies according to molecular structure, and the NMR analyzer interprets this structure by analyzing RF signals emitted by the spinning protons. Within seconds, the analyzer averages multiple pulses into a spectrum to reveal chemical species and concentrations.

The spectrum is then correlated with physical properties other than chemical composition, enabling determination of multiple parameters in a single spectrum.

Since NMR is not an optical technology, the analysis is independent of sample-state or physical condition. For example, small bubbles have little or no effect on analysis results. The sample passes through the magnetic field in a small tube, untouched and unchanged in any way, and can be returned downstream if desired.

For more information, visit

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Rosemount introduces PPB dissolved ocygen (DO) analyzer

Irvine, Calif. – Emerson Process Management-Rosemount Analytical recently introduced the Model 499A TrDO parts per billion (PPB) sensor.

Dissolved oxygen is an important measurement in boiler-feed water, determining trace oxygen in offshore oil-drilling seawater-injection wells, and in applications requring high-purity cooling water.

The 499A TrDO sensor is designed for use with models 10555 and 54eA amperometric analyzers.

Features of the model 499A TrDO sensor include:

  • Rugged construction;

  • Easily replaced membrane;

  • Automatic temperature compensation for changes in membrane permeability;

  • Automatic pressure equalization to correct for membrane tension; and

  • Rapid stabilization time following calibration and/or maintenance.

For more information, visit

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Cost effective level measurement for water and wastewater

Greenwood, Ind.Endress+Hauser recently introduced Waterpilot, a hydrostatic pressure sensor as a replacement for bubbler systems commonly used for level measurements of fresh water and wastewater applications.

Waterpilot’s compact design can include an optional temperature sensor and the whole thing fits in a standard 1 in. well casing.

Waterpilot is designed with a high mechanical resistance to overload and aggressive media. Its rugged design and construction feature NEMA 4X protection with a Gore-Tex filter for condensation-free pressure compensation.

For more information, visit

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Conferences, seminars, and exhibitions

Visit /calendar.asp for the latest in upcoming conferences, seminars, and exhibitions.

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October in Control Engineering

Cover: Wireless vs. wired networks
Wireless may not replace wired in critical applications, but a host of wireless equipment is starting to be used to save money in industrial settings. This article describes some of the basic advantages and disadvantages of each.

Open system reliability and safety
‘Be careful what you ask for, you just might get it.’ When systems were proprietary the suppliers had the responsibility of making all the parts and pieces play together. Now that systems are open and the components of the system come from multiple suppliers, the responsibility of making all the parts and pieces play together has shifted to the end user. This article will explain what users and their integrators need to do to ensure installed open systems behave well when the process under control is misbehaving. Contributed article by Dr. William Goble, founder and president of and recognized safety system expert.

How to connect the supply chain/ERP to the plant floor
Plant-floor systems and process automation software suppliers are connecting and integrating with enterprise systems and the supply chain, and vice versa. What should end-users consider when looking to provide and receive information into the enterprise and supply chain? What software vendors can help?

Intelligent Sensing (Machine vision, barcodes)
All kinds of sensors are ‘getting smart.’ From networking built in to complex, yet easy to use, software for vision systems, intelligent sensors are becoming an integral part of an automation system. In a time where manufacturing management asks control engineers to gather and disseminate vast amounts of real-time data, these products are key to success. As efforts to improve process uptime continue, built in diagnostics are essential.

Product Focus: Pushbuttons and switches
Original Control Engineering /Cahners Research examines trends and user issues with pushbuttons and switches. Recent product descriptions from leading suppliers will be included, along with research results.

Back to Basics: Temperature calibration
Here’s what to consider when calibrating temperature-measuring devices.

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