Control Engineering’s Process Control Newsletter for April 2002

By Dave Harrold April 1, 2002

In this issue:

The clock is ticking!
Do we need this law?
Do you know the answers?
Design for Six Sigma example
How does your PID loop rate?
Paperless recorder with extended security
Conferences, seminars, exhibitions, webcasts
April in Control Engineering

The clock is ticking!

For those with an interest in FDA 21 CFR Part 11, ‘Electronic Records and Electronic Signatures,’ I wanted you to know the FDA is soliciting comments on ’00D-1542 Draft-Guidance Document Electronic Signatures: Time Stamps.’

This document reflects the FDA’s current thinking regarding the time stamp requirements of 21 CFR Part 11, but don’t wait too long; the FDA allows 90 days for comments, and the clock started ticking on March 20, 2002.

View the draft guidance document at

Back to top

Do we need this law?

Last October, U.S. Senators James Jeffords (I-VT), Hillary Clinton (D-NY), Barbara Boxer (D-CA), and Jon Corzine (D-NJ) introduced Senate Bill 1602, ‘Chemical Safety Act of 2001.’ The bill was read twice on the floor and referred to the Committee on Environmental and Public Works (EPW), which is headed by Senator Jeffords.

According to Senator Jeffords, this bill is the results of a letter sent to President Bush by the American Chemistry Council requesting the federal government immediately begin a comprehensive assessment of security at chemical plants. Having worked in and around chemical plants the past 35 years I’m unsure if this is good legislation or not. On the other hand, this proposed legislation would have far less affect on me than on many readers of this newsletter. Therefore, I’m simply reporting what’s occurring and letting you decide what to do with the information.

You may read Senate bill 1602 at ; enter S1602 into the search engine.

You may access the EPW committee’s web site, and its member list, at

You may locate your senators via

You may reach The American Chemistry Council site at

Back to top

Do you know the answers?

‘Learning is not attained by chance, it must be sought with ardor and attended to with diligence.’ -Abigail Adams

A couple of months ago I began introducing a few basic instrumentation and control questions in this newsletter. From the feedback, several find them useful, so I’m going to continue.

This month’s questions focus on pH measurement and were obtained from a web site designed to provide study resources to high school chemistry students.

Convert each hydrogen ion concentration into a pH. Also, identify each as acidic or basic pH.

1. 0.0015

And the answer is:

pH = -log 0.0015pH = -(-2.82)pH = 2.82Acidic

2. 1.0

And the answer is:

pH = -log 1.0pH = -(0)pH = 0.00Acidic

Yes, a pH of zero is possible, it’s just uncommon. In fact, watch out for this trick test question. ‘What’s the pH when [H+]= 2.0 M?’ The answer is 0.30, it’s just very unlikely to occur.

3. 0.00010

And the answer is:

pH = -log 0.00010pH = 4.00Acidic

Learn more about pH and other chemical measurements at ChemTeam (excerpted materials above are Copyright O 1997 by John L. Park), available at

Back to top

Design for Six-Sigma example

Regular readers of this newsletter already understand I’m an advocate of reducing variability and continuous improvement.

I recently found what I consider a well done, yet simple presentation about applying the design aspects of the Design for Six Sigma process to achieve Six-Sigma performance. The example demonstrates the application of robust design concepts, Monte Carlo simulation, tolerance design, and a means of making early predictions (using certain assumptions) of the defect rates of a subsystem in order to limit the number of physical prototypes that need to be built.

You can view this simple, but informative presentation at

Back to top

How does your PID loop rate?

ExperTune (Hubertus, Wis.) recently introduced Control Loop Performance Evaluation. This is a tool ExperTune spokespersons say will let you explore and analyze loop performance tradeoffs, such as robustness and valve wear.

Information is presented graphically with bars comparing current control loop performance and robustness to ‘what-if’ scenarios. Process variable filters are considered in the analysis and the higher the bars in the performance and robustness area, the better.

In the valve duty cycle section, valve travel and reversals are compared for current and new controller settings. Valve travel is indicated as the total distance the valve moves in a normally operating control loop with noise. Since the controller’s goal is to obtain a desired level of performance with the least amount of valve travel (wear and tear), the lower the bars, the better. The number of times the valve changes direction (valve reversal) is also graphically indicated. The less often the valve changes direction, the less maintenance required. So again, the lower the bar the better.

More information is available from ExperTune .

Back to top

Paperless recorder with extended security

During my walk up and down the aisles of National Manufacturing Week in Chicago, I spent some hands-on time with Honeywell’s (Fort Washington, Pa.) paperless recorder with the extended security system (ESS) option installed. ESS permits administrative application of multiple user and privileges, requires user name and password to login, includes data encryption to prevent after the fact data manipulation, provides who, what, and when audit trail, and automatically logs out users following keypad inactivity. Honeywell is another of the paperless recorder manufacturers to make available installation and operational qualification (IQ/OQ) protocol documentation for the Minitrend and Multitrend Plus recorders, thus aiding customers achieve FDA 21 CFR Part 11 compliance.

More information is available at

See other Control Engineering coverage of the Industrial Automation Show at National Manufacturing Week at /nmw/nmw2002/default.asp

Back to top

Conferences, seminars, and exhibitions

Learn from experts in fieldbus technology in a Control Engineering Technology Webcast. Visit /webcast/archives/fieldbus.htm for this free, sponsored webcast: ‘FOUNDATION Fieldbus: An Open, Integrated Architecture for Information Integration.’

Control Engineering’s website includes registration for eight topical e-mailed newsletters, access to exclusive coverage from Control Engineering Europe , site search, Online Control Engineering Buyer’s Guide , and Automation Integrator Guide Online , with advanced search functions. Go to /

Control Engineering’ s website includes links to upcoming conferences, trade shows, and exhibitions:

Apr 15-20, Hannover Fair, Hannover Germany

Apr 15-17, Interphex, New York, N.Y.

May 21-23, Sensors Spring Expo, San Jose, Calif.

Jun 3-6, Embedded Systems, Rosemount, Ill.

Jun 4-5, ISPE Washington Conference, Arlington, Va.

Jun 25-27, Integrated Manufacturing Solutions Conference, Cleveland, O.

Sep 8-12, Wonderware Showcase, Orlando, Fla.

Sep 24-26, Sensors Fall Expo, Boston, Mass.

Oct 8-11, Center for Chemical Process Safety Conference, Jacksonville, Fla.

Oct 21-24, ISA Expo, Chicago, Ill.

Nov 3-8, AIChE Annual Meeting, Indianapolis, Ind.

Nov 4-5, ISPE Annual Meeting, Orlando, Fla.

Nov 18-24, Embedded Systems, Boston, Mass.

Nov 19-23, BIAS, Milan, Italy

Nov 20-21, AB Automation Fair, Anaheim, Calif.

Back to top

April in Control Engineering

Cover stories: Integrator registration Automation system integrators have to deal with an increasing complexity of hardware, software, and standards, often connecting new with existing systems. The Control System Integrator Association has created a registration program to certify integrators based on a number of key parameters.

Electronic records and regulatory compliance In 1997 the U.S. government released regulations for electronic record keeping and use of electronic signatures. Until about mid-2000, the regulation remained dormant, but now companies are being cited and fined for non-compliance with these regulations. This article examines the FDA 21 CFR Part 11 regulation and describes a method to use compliance activities to improve the bottom line.

New developments in discrete sensors Functionality and programmability of photoelectric sensors have increased. Trends in proximity sensors, network-ready provisions, and embedded intelligence are discussed, along with practical application advice.

Safety networks Hazardous locations and safety-critical situations need industrial network technologies as well. How are industrial networks and their connected devices continuing to adapt to these end-user needs?

Show: Sensors Expo A number of new sensor-related technologies important to industrial applications will be introduced at the May 21-23, San Jose, Calif., Sensors Expo show.

Product Focus: Transmitters Original research from Control Engineering/Cahners Research examines trends and user issues related to transmitters. Recent product descriptions from leading suppliers will be included, along with survey results.

Back to Basics: Valve calibration Here’s a simple explanation of how to calibrate control valves on a bench so they work well when process dynamics are applied.

Back to top