Voices: Rezabek

Tinker with Defaults to Get Value From Smart Devices

Empower Your Staff So They Can Show Thoughtful, Proactive Use of Intelligent Devices, says Writer John Rezabek

By John Rezabek

When our technician saw an alert, an instrument alarm of sorts that would typically show up in his AMS Device Manager alarm summary, he ignored it. It was a "travel accumulator” alert. Like an odometer for a valve, it expresses the totalization of valve travel. Like the one in your car, it’s not the best indicator of "service needed soon.” Typical automobile oil change guidance goes something like "8,000 miles unless your driving includes dusty, hilly, stop-and-go, etc. Then change every 3,000 miles.” We’re left confused about when to change the oil, and so it is with valves.

The right thing to do for our automobile might be to have our oil analyzed every 2,500 miles or so, and characterize its viscosity, contamination, oxidation, water, etc., to see how far along it really was from "like new” to "totally spent.” Maybe you can skip an oil change, or maybe it should have been changed at 1,000 miles. Like cars, valves vary greatly in the severity of their service, but the cost and complexity of maintenance, as well as the high cost of neglect, are orders of magnitude higher than a stop at the corner Quik Lube. Preemptive valve maintenance — the equivalent of the guy who changes his car’s full-synthetic oil every 2,500 miles — is difficult, dangerous and burdensome on operations and maintenance schedulers. Breakdown maintenance can have dire consequences for plant availability. Ideally, we want our smart positioners’ alerts to wake us up at the ideal time — long enough before a failure to plan and schedule a repair. Many times, this is well within the realm of possibility, but probably not with factory default alert settings.

Analyzing a setting or alert at any level of travel accumulation is a bit of a conundrum. Do we have any basis for determining at what "mileage” we want the "needs maintenance soon” lamp to light up? What does 1 million percent of travel represent?

Every fieldbus valve positioner I’ve seen and most of their HART brethren have some setting for a travel accumulation diagnostic, and if you don’t bother to change it or turn it off, it will come on at the default setting. All the Metso ND9000 positioners I’ve looked at have a default of 250,000 (percent, one would assume) and also have the same setpoint for actuator travel. So I get both at about the same time, assuming no slippage between actuator and valve stem. Does this mean the actuator needs service at the same time as the valve?

 Probably not. It’s not Metso’s fault. End users need to decide whether 1) we enable a given alert, 2) where exactly we want to set the alert and, oh yeah. 3) what priority do we give it? It would be nice to determine specific actions we want technicians to take. And when an alert comes in, and I decide I don’t care (yet), how do I reset it or raise it to a new threshold?

A Fisher valve (www.emersonprocess.com) positioner’s travel accumulation alert is set at 1 million. I don’t believe the folks in Marshalltown are implying that their valve will go four times as long as one from Neles. It’s just a different arbitrary default. HART and fieldbus positioners and fieldbus "placeholders” in DCS engineering tools all ship with a similar set of defaults for scores of diagnostic settings. There are 10 tabs of settings for a Fisher DVC6200, including alerts for supply pressure (high and low) and temperature (high and low), drive signal, travel and maybe 20 others. The default settings could leave the impression that most of them are set so they’ll never bother you.

If users want to get value from their smart devices, they’ll have to start tinkering with these defaults. Turn off the vague ones like travel accumulation. Enable and tighten up settings like supply pressure, travel deviation or stiction that have a chance of alerting us to a potential breakdown. Most important, train and empower your people, so they can demonstrate how thoughtful, proactive use of intelligent devices can have a real impact on reliability. That won’t come "by default.”

More from this voice

Title

Selling Diagnostics to Management, Part 2

Dear Plant Manager, We See a Chance to Get Distinctive and Strategic Value From Intelligent Devices; Give Us a Chance to Prove We Can Do It

05/07/2012

Siemens–Not Just for Profibus Anymore

In PCS 7 We May Have the First SIL-Capable Logic Solver With Native Support for Foundation Fieldbus

06/06/2011

Simplifying Fieldbus Device Calibration

Creative End Users Have Been Exploring the Use of 802.11 Wireless to Display their DCS Interface on a Wireless Laptop or Notebook PC

08/12/2009

Smart Pipe--One Bus to Rule Them All

What Revolutionary Technology Is Coming Along That Will Kill Fieldbus?

06/05/2012

Surprise! Field-Based Control Beats DCS

It Is Evident That Device-Based Control Exceeds DCS-Based Control in Reliability and Performance

03/04/2010

The Island of Misfit Instruments

The Island of Misfit Instruments Could Become a Great Place for Learning and Help Shape the Future When the Aging Systems Will Be Replaced

10/05/2010

They'll Make a Better Software Fool

Because We're Working With Hazardous Processes, We Have to Think Through the Consequences of Every Errant Mouse Click

10/11/2013

Tinker with Defaults to Get Value From Smart Devices

Empower Your Staff So They Can Show Thoughtful, Proactive Use of Intelligent Devices, says Writer John Rezabek

07/24/2014

Tolerate less redundancy

Today, with Foundation fieldbus, the old redundancy paradigm no longer applies. Chances are, though, it isn’t free. So where should you apply it to achieve the fault tolerance you need?

12/05/2006

Training Wheels for Fieldbus

Even in Lean Times, There Are Ways to Get a Fieldbus Testbed If You Think Creatively

02/06/2009

Trunk Testing Tribulation

It's Challenging to Power Down Segments While the Plant is Down, Let Alone While a Process Is Up. Powering Down Is Not an Attractive Option

12/04/2012

Using Fieldbus in your HMI

Digitally Integrated Field Device Information Is Useful to Your Operator

10/06/2008

Using Your Best People

Getting to Know Those Working Around You. How Did They Become an "Instrument" Person?

03/02/2012

Want Open Standards? Work at It

End Users Have to Insist Their Favorite Suppliers Support Open, Interoperable Solutions, or We'll Remain Saddled With the Closed, Proprietary Ones

12/30/2011

We Get It - Wireless Works

Can Anyone Remember an Instrument Technology That Was Marketed With Such Persistence and Zeal?

11/01/2010

When to Use Control in the Field

Exploiting Control in the Field Is Never an All-or-Nothing Proposition

11/02/2012

Which Bus--If Any--for On-Off Valves?

Profibus PA and Foundation Fieldbus Give the End User Flexibility to Integrate On-Off Valves Wherever the Process Places Them

08/31/2011

Why Industrial Couplers Aren't Commodities?

Maybe We Should Ask If Couplers Can Be Procured on the Basis of Cost Only

02/26/2013

Will Wireless Replace Fieldbus?

Hardwired Instruments Are Going to Be Around Until a Generation of Plant Operators Retires

09/05/2008

Wired or Wireless - Just DO It

Why Let Another Week Slip by with All Your Smart Devices Asleep on the Couch? Just Do It

07/13/2010