Save time and money with field calibrators

 By Wayne Labs, Contributing Editor

ccurate instrumentation ensures accurate measurements that keep processes under control, prevent waste, and may protect human life as well. Field calibrators—also known as handheld calibrators—let engineers and technicians apply secondary calibration standards to devices and instrumentation without having to lug around heavy equipment. Today’s field calibrators work hand-in-hand with software, logging essential data when technicians use them on site. The software receives the original device data from the calibrator and provides it to the handheld calibrator when it’s time for the technician to make additional site visits.

Measuring and Calibrating Current Loops
Electrical engineer John Gale is responsible for the development, design, programming and engineering of industrial control, data acquisition, and continuous emissions monitoring systems for ACS, Inc. (www.acs-acs.com, Bellingham, Wash.), a company that designs and manufactures incineration and scrubber systems. Some of ACS’ systems have 24 current-loop inputs and 12 current-loop outputs that must be calibrated at commissioning and during routine maintenance and calibration intervals. To verify the accuracy of the equipment under calibration, Gale typically had to go through each loop several times.

ADVERTISEMENT GOES BOTH WAYS   Fluke's 789 Process Meter is both a digitial multimeter and a loop calibrator. It has a 24-V loop supply reducing the need for taking a separate power supply when doing offline transmitter testing.

Using Fluke’s (www.fluke.com, Everett, Wash.) ProcessMeter (Figure 1) which combines the functions of a traditional multimeter with a current loop calibrator, Gale reduced the time needed to calibrate the systems. In addition, on site visits he was able to eliminate one piece of equipment as well as extra batteries and test leads. With more than 30-years experience in the electronic/electrical industry, Gale has used several manufacturers’ meters and finds the ProcessMeter to be rugged, accurate, reliable, and with its large display, easy to read.

Smart Manometer Calibrator
BC Group International (www.bcgroupintl.com, St. Louis) is a leading provider of test and measurement equipment for the worldwide technical services marketplace. It is a one-stop-shop, offering sales of test equipment and tools, plus calibration and repair services for most types of test equipment. Over the last five years, BC Group has sold several hundred Meriam (www.meriam.com, Cleveland) Smart Manometer calibrators to a wide variety of instrumentation and control customers in a variety of industries including refining, chemicals, manufacturing, pharmaceuticals, food, and medical.

According to Mike Clotfelter, BC Group vice president, Business Development, what makes the Smart Manometer calibrator desirable is the display that provides engineering units in mm Hg, mBar, and psi—along with eight other engineering units. The accuracy specification is 0.05% full scale, approximately 72 psi on the Model 350DN2000 (Figure 2).

ACCURACY FOR OEMs
Meriam's Smart Manometer calibrator can be used for applications where very high accuracy is needed for gauge pressure of 20, 200, and 2000 psi.

“Until BC Group found the Smart Manometer,” says Clotfelter, “we had to offer two different manometers to obtain the range, engineering units, and accuracy required for servicing our applications.” According to Clotfelter, customers find the device to be very reliable and report that it stays within published specs year-after-year without calibration.
The calibrator handles clean, dry, non-corrosive gases; measures differential pressures of 20, 200 and 2,000 in. wc; checks gauge pressures of 20, 200 and 2,000 psi; and works in temperatures from -4–122° F. Pressure connections are 1/8-in. NPT. The device also handles absolute and vacuum pressures, and is NIST certified.

Documenting Acquired Data
The Industrial Company (TIC, www.tic-inc.com), through nine regional operations, provides industrial construction services to a diverse client base across the U.S. Headquartered in Steamboat Springs, Colo., the company typically uses its own engineering and construction people for the commissioning and startup of control system instrumentation.

According to Jim Mitchem, technology manager, checking out the hundreds of newly-arrived instruments and calibrating them prior to installation is largely a manual job, and recording these activities is often a problem. If the documents become illegible or lost, or the data itself is not secure, the calibration has to be redone, resulting in lost time and significant cost overruns. In addition, extra personnel are often needed to collect, review, edit and organize turnover documentation to determine that the calibration has been done correctly, and that all documentation is complete and accurate before presentation to the owner. The extra work can lead to missed project milestones and delayed completion dates.

At the Front Range power project (Fountain, Colo.) more than 1,200 field devices in a 480-MW power station had to be calibrated and documented prior to turning the plant over to the owner. Engineers at TIC had been evaluating calibration management systems for years, looking for an effective way of documenting the data obtained through the use of field calibrators. Although not looking for a predictive maintenance system, Mitchem noted that Emerson Process Management’s (www.assetweb.com, Asset Optimization Division, Eden Prairie, Minn.) AMS Suite: Intelligent Device Manager (Figure 3) filled the bill because it provides device data and calibration parameters for all commonly used field instruments.

ASSISTANT SNAPS TO

Emerson Process Management's Calibration Assistant snap-on application works with AMS Device Manager and common hand-held calibrators such as Fluke's Model 744.

The AMS Device Manager also stores the data required for calibration of any given instrument. Because the technician is not required to enter the information through the field calibrator’s keypad, downloading this data for a handheld Fluke 744 or other similar calibrator is quick and accurate. Each instrument is calibrated on the bench using established procedures, and the results are uploaded to the database. The data transfer is fast, easy to do, and free from hand-written errors.

Calibration results for each instrument are automatically archived, providing the basis for documentation. If the calibration history of any field device is needed, it is easily available on a PC or laptop for review or print out. In the future, technicians can download the data to the field calibrator to check up on devices that may be causing problems.

TIC estimates that it has realized $50,000 in cost avoidance using the software in conjunction with handheld calibrators during instrument calibration. Technicians had to spend only half the time necessary to accomplish the calibration for this new facility, and the software has made it possible to get 100% acceptance of calibration documents on all 1,200 field instruments. According to Mitchem, TIC decided to use the AMS Device Manager for instrument calibration on three more large construction projects because of the favorable results it had at the Front Range power project.

Save Time, Effort, Dollars
Handheld field calibrators make it easy for technicians to visit instrumentation sites without the need to carry heavy equipment. Whether they’re used to calibrate instruments that measure temperature, pressure, or other process variables, these portable devices save time and money. When engineers couple calibrators with the right software, they find that keeping track of a large number of field instruments is much easier, eliminating all sorts of manual recording of information.