Essentials of Modern Measurements —- Book Review

“Essentials of Modern Measurements and Final Elements in the Process Industry” is a new book assembled by author Gregory K. McMillan, with a host of contributing writers.  I first became aware of this new book  from a post at ControlGlobal.com, one of the leading industry news and editorial sites on Internet.  I was intrigued by the fact that someone took the time to put a new book together that was about process MEASUREMENT and not control automation.  I remember GIGO (garbage-in, garbage-out) and still place a strong priority on measurement technologies rather than the control system.  In the end, both are necessary but it is my opinion that many within the Measurement, Control and Automation industry seem to have forgotten about the process measurements and their importance.

I have completed much of the Level Measurement section, Section 5, which begins on page 229 and continues through 273.  I have a few observations and constructive comments regarding this section of the book:

MEASURING SOLIDS LEVEL IS ABSENT.  This book is definitely well written.  My hat is off to the writers of this section on Level Measurement.  They and the editor(s) did a fine job in writing the material.  The illustrations are also well done.  Bravo!  However, there is a glaring absence of even a mention of level measurement of powders and bulk solids, which can be just as complex or more complex than liquid level measurements.  I view this as a deficit in the book and feel a few pages could have and should have been devoted to this topic.  A White Paper on the subject of continuous level and inventory measurement of powders and bulk solids may serve to fill the gap.

ABSENCE OF POINT LEVEL SENSING. Well I guess some folks don’t consider point level “level measurement” and in the strictest possible sense of the phrase it is arguable.  However, even third-party market research firms such as Venture development Corporation include point level with continuous level when assessing the Process Level market.  This subject should have been included, especially given the introduction of several point level products from a variety of companies rated for SIL-2 use, such as this unit from Magnetrol.  I also point to the recent recommendation by the board that reviewed and assessed the aftermath of the Buncefield accident late in 2005.  One of the conclusions stated that the failure of the inventory measurement sensor system and the absence of a separate overfill detection and prevention system may have been contributing factors to the accident.  Point level sensors have a place within the “level measurement” arena.

FOCUS ON DP, RADAR AND ULTRASONIC. I do agree that these are very important technologies.  I also concur that Radar, whether in its contact guided wave form or non-contact form, is the fastest growing technology for level measurement.  DP and Ultrasonic also are large segments and heavily used.  However, the absence of any discussion about Magnetosrtictive technology, Displacers and only a limited discussion on RF Admittance capacitance type sensors was disappointing, and those are for liquid apps.  In addition, the category of smart weight & cable inventory systems, like all else for solids, was absent as well.

I definitely recommend this book as one of the better reference books available.  However, I do feel and wished the above deficiencies would have been corrected before publishing.

Joe Lewis
BlueLevel Technologies, Inc.
www.bluelevetechnologies.com
joe@blueleveltechnologies.com

Failure of Tank Overfill High Level System

What happens when your high level indicator fails without warning?  Everyone knows the answer and we have talked about it before.  The unknown failure of a high level sensor that is used for overfill protection can result in an overfilled condition that means lost material, clean-up, damage to equipment and even catastrophic events.  People can and have died.  This is preventable!

Level detection devices meeting SIL2 are commonly available for liquid level applications.  However, not for powders and bulk solids.  While loss of life may not be as high a risk with powders and solids, it remains a costly occurence to overfill a silo, even with plastic pellets.