Field Calibrators & Field Management - Control Global

Field Calibrators

& Field Device

Management

eHANDBOOK

TABLE OF CONTENTSValidation in lieu of calibration 4

Adding simple checks between full verifications can raise reliability.

Calibrator communications 6

Verifying field devices involves specific demands that wireless could meet, if we let it.

Be strategic about CBM 8

Five mistakes to avoid when implementing condition-based maintenance.

Instrument specification 10

Look to the past to avoid the problems we’re seeing from trends in current practices.

AD INDEXACROMAG • www.acromag.com/sc 3

eHANDBOOK: Field Calibrators & Field Device Management 2

www.ControlGlobal.com

Visit www.Acromag.com/scTO LEARN MORE

New Dual-Channel ProgrammableTransmitters & Signal Splitters

■ Dual channel saves you money

■ Front facing terminal blocks saves you time

■ High performance increases accuracy

Acromag.com

877-295-7066

Linkedin.com/company/acromag

MADE IN USA

ISO9001AS9100

IECEx

Remote I/O solutions that you can depend on.

https://www.acromag.com/sc

“Sometimes just OK is not OK,” says

the narrator of the cellular provid-

er’s TV commercial. The scenes

are humorous, as the befuddled customers

are confronted by lackadaisical service pro-

viders, whether a surgeon, auto repairman

or tattooist. In our discipline, we hope our

service providers have higher aspirations for

excellence. But for our ultimate end users and

the enterprise—who rely on our discipline to

provide interlocks that ensure the process

is safely parked when limits are exceeded, a

clear and unhindered view of complex and

processes to operators, and measurements

with the consistency and repeatability to sup-

port long-term forecasts for productivity and

reliability—are we exceeding “just OK?”

We read of and sometimes experience

instances where “just OK” failed. This might

mean the “squeaky wheel gets the grease” for

a spell, but it rarely results in a reconnoitering

of processes and priorities. As they read of

calamities that befall their peers and com-

petitors, corporate board members wooing

investors want assurance that their cash-pro-

ducing but complex and scary assets aren’t

going to make any headlines. Despite this,

adding positions like “instrument reliability

specialist” may be a dream, and even if we’re

authorized to create such positions, the com-

petition for competent I&C talent is intense.

How does one ensure the integrity of the I&C

system? Is there a preventive or proactive

maintenance scheme to perform and doc-

ument calibrations on a routine basis? Do

you scramble during infrequent process out-

ages to exercise instruments and interlocks,

and document any faults that would not

Validation in lieu of calibrationAdding simple checks between full verifications can improve safety and raise reliability.

By john Rezabek, Contributing Editor



otherwise have been revealed? Are HAZOP

revalidations and other process hazard anal-

yses constantly identifying instances where

measurements are part of a vital “layer of pro-

tection?” Run-to-failure may be “just OK” for

fewer and fewer devices and systems.

If we’re challenged to physically validate a

measurement through calibration, i.e., apply-

ing a known, traceable standard to a device

and verifying all indications agree within toler-

ances, perhaps we can employ other features

or assumptions. For decades, designers of

safety interlocks have favored analog trans-

mitters in lieu of switches, i.e. low level in a

knock-out drum. Many such measurements

are now triplicated for fault tolerance as well

as reliability—two out of three must vote to

invoke an interlock or trip.

The old switch only needed to be accurate at

one point—the trip setting. Its downfall was

that any fault less self-revealing (such as, if the

switch was stuck), you wouldn’t know if you

didn’t test it. Now, when triplicated analog

transmitters are employed, it might suffice to

simply verify the trip point alone as opposed

to doing a five-point calibration. How import-

ant is it to know a level or a pressure within

the 1% tolerance you might enforce for cus-

tody transfer? If the trip point isn’t within

a hair’s breadth of the safe operating limit

(and why should it be), then that margin

might better dictate severity and frequency

for testing.

We have an array of flowmeters that

defy validation without using an external

meter-proving loop. One option might be to

perform a validation based on other mea-

surements. For a reboiler steam flow, an

energy balance around the tower can vali-

date it against other tower conditions, and

adequately surmise whether a flowmeter

is reading adequately. Simple relationships

between valve percent-open and flow can

identify candidates for further scrutiny—if a

flow is substantially less at the same operat-

ing point as a month ago, the procedure can

trigger an investigation or a more meticu-

lous calibration.

If we must tackle this challenge—achieving a

level of excellence that meets the expecta-

tions of our end users, without much infusion

of resources—we can explore opportunities to

exploit features of present-day systems and

measurement devices. We can exceed “just

OK” by creating some diagnostics to validate

key measurements, and examine them rou-

tinely. If you document your routine, it may be

enough to check the box for validating numer-

ous measurements, without exhaustive and

labor-intensive calibrations.

For a reboiler steam flow, an energy balance around the tower can validate it against other tower conditions, and

adequately surmise whether a flowmeter is reading adequately.



With the increasing use of wired

and wireless digital communi-

cations, technicians and field

engineers are communicating with and per-

forming maintenance on field devices from

practically anywhere—and often not at the

transmitter face with screwdriver in hand to

“tweak the pots” unless necessary to force

a signal or isolate the device, as they would

when calibrating. Many practitioners believe

that because a digital transmitter is factory

calibrated for a wide signal range, and they

can configure the device anywhere within the

range, that calibration and configuration are

the same, which is certainly not the case.

Configuration refers to setting transmitter

parameters only, without any signal forcing

other than simulation of inputs, and thus

no traceability to a reference. Because they

don’t need to simulate input signals, sev-

eral configurators on the market are based

on a ruggedized, perhaps intrinsically safe

tablet or smart phone. These devices, in

addition to supporting the field protocol,

typically through a Bluetooth or USB acces-

sory/modem, also often provide WiFi- or

cellular-based Ethernet connectivity to

communicate with the enterprise mainte-

nance system and control system.

Calibration, on the other hand, is com-

paring the device under test against a

traceable reference instrument, and doc-

umenting the comparison. Therefore, to

calibrate a transmitter, the input needs to

be generated at the same time the output

is being measured. If the calibration is

done with a documenting calibrator, it will

automatically document the calibration

Calibrator communicationsVerifying field devices involves specific demands that wireless could meet, if we let it.

By By Ian Verhappen



results. Fortunately, most calibrators with

digital communications at least have the

documenting capability, thus eliminat-

ing transcription errors while providing

time-stamped end-to-end traceability.

Unfortunately, some calibrators have limited

memory, and may only be capable of han-

dling as few as 20 data sets before needing

to be downloaded. On the positive side,

this will encourage technicians to download

their results every day, but the objective of

technology is to make life easier.

Another key consideration for calibrators

is their ability to isolate the input from the

output since, as we know, the simple act of

measuring something affects the measure-

ment. With calibrators, we’re both forcing

or inputting the measurement and measur-

ing the resulting output. In my experience,

running off battery is a great way to remove

one potential common-mode source of

error—the power supply, especially if it’s

an AC source. Mind you, I was using a lap-

top-based tool, so it would not have the

isolation that a properly designed industrial

instrument will, but it proves once again

that cheap and multipurpose are not quite

the same as dedicated and industrial.

The challenge with many calibrators is get-

ting the documenting information in their

memory into the main computer storage

platform. All calibrators communicate

with the calibration module that is, hope-

fully, part of or at least accessible from the

instrument maintenance system. The con-

nection between the calibrator and hosting

computer uses a wide range of technologies

from serial (tough finding computers with

this connection still) to the more common

USB interface, with the few that now support

Bluetooth about the only current wireless

option. There are also still some that require

manually pulling the SD card and installing

it in the calibration company’s standalone

proprietary software, then porting it from

there (sometimes as Excel files, though most

systems support SQL) to the enterprise’s

maintenance software for archiving and,

more important, access by QA and potential

statistical analysis and control.

Calibrators continue to get better, however,

as we can see, there’s still room to improve.

I’m confident we’ll soon see devices with

bidirectional communications directly from

the field to the quality system to support

and prompt technicians on their rounds,

while populating the central database. All

we’ll need then is the infrastructure in the

plant to make it possible; so once again we

have a Catch 22—no capable field devices

without infrastructure, and no infrastructure

because we don’t have enough capable

field devices to justify installing it.

Running off battery is a great way to remove one potential common-mode source of error —the power supply, especially if it’s an AC source.



You’re likely aware of the concept

of condition based maintenance

(CBM): essentially, performing

the optimal amount of maintenance only

when required (and on your own sched-

ule). Much progress has been made on CBM

lately, including many successful program

launches. Yet, these programs are not

without risk. When considering your CBM

strategy, you should be aware of some

potential pitfalls:

Not involving everyone: When start-

ing a CBM system, a vital first step

is to ensure all key stakeholders are

involved, engaged and committed to

the plan. This may seem trivial, but sur-

prisingly, it isn’t always done for CBM

system deployments.

In one case, an engineer led a pilot pro-

gram and installed sensors that fed

predictive software, but the engineer only

gained partial commitment from the main-

tenance staff. The program struggled, and

didn’t gain much traction. This could have

been avoided if the maintenance staff

were more involved on the front end.

Likewise, integrating the CBM program

with the existing computerized mainte-

nance management system (CMMS) or

other specialized software must be con-

sidered. The closer the two can mesh,

the better. Your staff is probably com-

fortable using the CMMS to schedule and

track maintenance. CBM will enhance this

system, not necessarily replace it. Make

the integration between the two as simple

Be strategic about CBMFive mistakes to avoid when implementing condition-based maintenance.

By Bryan Christiansen, Founder and CEO, Limble CMMS



as possible to ensure that your staff will

use both systems effectively.

Scoping too large: Buzzwords like smart

technology, IoT and Industry 4.0 may elicit a

variety of reactions from industry profession-

als. These reactions can vary from skepticism

to enthusiasm. However enthusiastic the

team is, it’s best to stay grounded in your

approach. A CBM program is perhaps best

viewed as a tool to help your operation. As

with any tool, it can help make things easier,

but it’s only valuable if used properly. Thus, a

broad scope implemented rapidly can quickly

becoming overwhelming and lead to a poten-

tial program failure. To fight this, start with a

pilot to learn and adjust before going all in.

Quantity over quality: An ambitious and

cost-conscious engineer may be tempted

to purchase as many low-cost sensors as

possible and place them everywhere in the

plant. This potentially introduces a new

problem of sensor administration, where

more time and effort are spent in replac-

ing cheap sensors than in using them for

improving maintenance.

Rather than multiplying sensors to gather

extra data, be more strategic in your

approach. Use quality sensors to gather the

most relevant information first. Further sen-

sors can be added as needs are identified.

No sensor management strategy: With the

potential influx of new sensors, you must

consider your sensor management strategy.

For example, how often will you check or

calibrate them? Will they feed data through

PLCs, DCS or a separate network? You will

want to find a balance between adding bur-

densome PM procedures, yet gaining value

from your new data insights.

Using wireless sensors adds more com-

plexities. A battery strategy will need to be

thought through. Consider how you’ll check

your device battery life, and at what thresh-

old you’ll respond. Who will be responsible

for this task? A good CMMS integrated with

your CBM sensors will solve a lot of these

complexities. All these questions should be

answered as part of your CBM deployment.

Security strategy not considered: The

proliferation of wireless technology allows

cost-effective and rapid deployment of

CBM. Particularly in areas with electrical

classification requirements, the cost savings

in avoiding specialized wiring are consider-

able. In the past five years, the possibilities

of electronics in manufacturing have

increased substantially.

Allowing communication between PLCs

and business LANs has great risks. The

possibility of manipulating a machine from

an external network must be eliminated.

A good understanding of proper network

architecture (DMZs, process LAN vs. busi-

ness LAN, etc.) should be a requirement of

your CBM strategy.



Greg: Instruments provide the view into the

process and means of controlling it. If they’re

not telling the truth, we’re in serious trouble. If

you can’t measure it, you can’t control it.

Mike Laspisa offers his insights as to where

we are now and where we should be with

instrumentation specification based on

37-plus years working in the instrumenta-

tion and control (I&C) discipline, including

32 years as a lead I&C engineer or manu-

facturing plant staff I&C engineer. I spent

most the of the 1970s in instrument and

electrical (I&E) design and construction, and

to this day, the performance of instrumen-

tation is foremost in my mind. Mike’s goals

are very similar to mine in terms of wanting

to share our knowledge often learned the

hard way to help automation engineers do

what’s best.

Mike, what were the original intents and

methods for I&C specification from the late

1970s to the late 1980s?

Mike: Field device importance was held

in high regard. Measurement and control

device specification was a science, and

could only be learned on the job. I&C engi-

neers were considered an important asset

by both the company and the client. Instru-

ment engineers specified measurement

devices, and selected and sized control

valves, regulators and safety relief devices

using process data, process and instrument

diagrams (P&IDs), and pipe specs. A control

valve outside sales engineer would review

the engineer’s selection and discuss difficult

applications. Valve sizing calculations were

always done by the engineer doing the

valve specification.

Instrument specificationLook to the past to avoid the problems we’re seeing from trends in current practices.

By Greg Mcmillan



Device selection took into account both

application requirements and device

cost. However, performance was the pri-

mary selection criteria. Process data was

analyzed by the I&C engineer for each

measurement and control application,

including control valve sizing pressure

drop, flow measurement turndown and

multiple case studies, if applicable. Accu-

racy, advanced control strategies, ratio

blending, batch addition resolution and

many other requirements were discussed

with process engineers during joint P&ID

development.

However, mass flow measurement choices

were limited (e.g., load cells, weigh belt, and

volumetric flow with pressure and tempera-

ture compensation by remote electronics or

computational module).

Greg: How would you describe our current

situation?

Mike: Project bottom line focus has led to

cost-effectiveness becoming almost more

important than performance in instru-

mentation and control device selection.

In addition, I&C device vendors are being

asked to select/size field devices more

often based solely on the data provided

on a datasheet. A reduced budget for I&C

specification work is now expected for proj-

ects and by some clients. Unfortunately, I&C

device vendors are using a younger inside

sales force that seems to rely mostly on

software for quotations without the expe-

rience to ask the right questions or quote

needed accessories.

Fast-track engineering has almost become

the standard. This sometimes leads to pre-

paring I&C device specifications without

the necessary information to specify them

completely. Also, process data is usually

provided late, and is furnished incomplete

or in partial installments. I&C engineer value

or project early involvement is questioned

by project management. Process or some-

times even project engineers think they

can make the early decisions on required

I&C devices, or assist the client in P&ID

development.

Relying on vendors to select and/or size

I&C devices has negatively impacted devel-

opment of I&C specifying engineers. This

has this led to I&C engineers not question-

ing process data and issuing incomplete

datasheets. Reduced budgets and fast-

track engineering have also compromised

the datasheet checking process. The focus

now appears to be more on checking tags

against P&IDs rather than application infor-

mation (sizing, materials of construction,

end connections/rating, pipe specs, etc.)

and the completeness of the critical pro-

cess data required to support the sizing and

selection of the device.

On the other hand, there are some bright

technology developments that have made



I&C device applications easier (and more

forgiving), such as mass flowmeters,

smart transmitters with wide rangeability,

multivariable transmitters, radar level trans-

mitters and digital valve positioners.

Greg: I&C engineers should ask process

engineers what accuracy is required. In

my experience, the accuracy they want is

aggressive and was often not achievable

until recently.

Mike, how does this history or commentary

relate to instrument specification work at

engineering, procurement and construction

(EPC) firms?

Mike: When I was reviewing project work

before I retired, I observed a number of

specification deficiencies that included

incomplete or incorrect datasheets. Cal-

ibrated ranges didn’t always take into

account the minimum, normal and maximum

process requirements and sensor rangeabil-

ity. I’ve seen datasheets where the vendor

was to select the device size, model, trim,

etc. from limited or possibly unintentionally

skewed information (e.g., all globe valves

with 5 psi valve drop for sizing, regulators

using pilots where they weren’t required,

etc.) Some specific application requirements

(e.g., magmeters missing ground straps/

rings/ground electrodes; flow primary ele-

ment selection not compatible with process

pipe/duct; analytical probe connection

requirements not considered during spec-

ification; level measurement selection not

compatible or practical for application) were

not specified correctly. Is this a checking

issue, a philosophy issue (i.e., leave it up to

the vendor whenever possible), or a misun-

derstanding of what is required?

The interface with piping designers, includ-

ing in-line installation detail preparation,

is more after-the-fact than timely to the

piping design effort. Packaged system

instrumentation is a shared responsibility,

but process design usually is in the lead.

Historically, I&C does not get involved

with the measurement requirements, only

the hardware preferences, control system

choices, and device signal levels.

Greg: We have to be especially careful to

make sure packaged equipment suppliers

use the latest and best technology consis-

tent with plant standards.

On the other hand, there are some bright technology developments that have made I&C device applications easier

(and more forgiving), such as mass flowmeters, smart transmitters with wide rangeability, multivariable transmitters, radar

level transmitters and digital valve positioners.



Mike: The package instrumentation, control

devices and control system (including the

interface with the plant control system)

must meet the equipment specification

expectations/requirements (e.g., manufac-

turer or equal, type or series, and control

system preference). There have been many

examples where the plant standards or even

preferred vendors were ignored to save

money by accepting OEM devices well after

the specification phase.

Greg: What’s needed for a much better

future in the specification of I&C devices?

Mike: Better use of appropriate instru-

mentation and control device learning

opportunities (courses, exhibitions, free

vendor/manufacturer seminars, lunch-and-

learns, asking a lot of intelligent questions

and mentoring). Provide internal or external

technical resources to discuss device-type

applications during datasheet preparation.

Develop the preferred role of vendors and

I&C engineers in selection and sizing of I&C

devices. Discuss the expectations for instru-

ment process data analysis. Determine the

critical data fields or notes for the different

I&C devices. Datasheet checking must cover

technical content as well as device checks

against P&IDs for tag and service.

In addition, see the “Instrument Data-

sheet Preparation Flowchart” for the

recommended approach to specifying

instrumentation and control devices.

Develop a standard naming convention for

instrument package workbooks, worksheets

and archiving. Discuss vessel connection

responsibilities, requirements and impact

on device specification. EPC firms need

to get I&C engineers more involved in the

packaged equipment system specification

process and bid review. Process engineers

commonly use vendors to create their pack-

age specifications, but they rarely have an

I&C engineer involved in any conversations

or meetings.



Documents

Field Calibrators & Field Management - Control Global