Fluke 753 [3/5] How is calibration performed

3 Fluke Corporation Calibration and documentation for process manufacturing: Costs, benefits and feasibility

How is calibration performed?

Calibration is typically performed either where

the device is located (called in situ calibration,

from the Latin for “in position”) or in an instru-

ment shop.

• In situ calibration typically tests only the

performance of a device’s transmitter and elec-

tronics (unless there is some way of valving

• In-shop calibrations are both more thorough

and more time consuming. Additional paper-

work must be submitted, downtime scheduled,

and then the device must be removed, trans-

ported, calibrated and then reinstalled.

Permitting and paperwork

Administrative tasks, from getting permits to

documenting and filing results, can add to the

cost and time required to perform even an in-

situ calibration. As Ian Verhappen, of Industrial

work to one long route of multiple calibrations, in

place of performing one-off calibrations.

Why is documenting calibration

problematic?

Traditionally, documenting a calibration has

meant using a log book to hand-write the date

and time, the pre-calibration readings, the post-

calibration readings, and any other observations

the technicians made. Surprisingly, many plants

continue to document calibration work by hand.

The data in hand-written records is often simply

illegible or insufficient. “Documentation/tran-

scription errors are likely more significant than

the field costs (of calibration) themselves,” says

Verhappen. “How many times do you get illegible

information on a work order, and how often is the

data entered actually useful with statements like

‘Completed’ or better yet ‘recalibrated’ without

saying recalibrated from what to what, or ‘fault

found and repaired’ or simply ‘repaired’ without

Many facilities store field data in more than one

database. Calibration data entered in the opera-

tions database may not be cross-entered into or

accessible by the maintenance database.

Several methods are being used to reduce the

time and cost of calibration and documentation,

including:

• Installing more digital instruments and valves

• Using interconnected asset management soft-

ware to help manage documentation

graduated large numbers of skilled workers will-

ing to work in manufacturing as operators and

technicians. They performed the majority of pro-

cess calibrations, using the traditional pen-and-

paper methods referenced above.

Starting in the 1960s, however, young people

became less interested in manufacturing work,

and those employers began having difficulties fill-

ing positions.

The 1980s brought budget cuts and layoffs.

doing rounds. It is more common to have many

less, and calibration rounds often become an

afterthought,” a plant engineer commented at a

recent section meeting of the International Society

of Automation.

While those reductions in team size would

seem to be balance out the decreased workforce

supply, another problem has since developed.

Smaller teams have less time for mentoring and

on-the-job-training, to the point where equip-

knowledge walks out the front gate,” says the

Chief Instrumentation and Controls Engineer of

a large Midwestern refinery, “and sometimes it