Article Ref: I-004

Weights and Measures Connec�on, Vol. 9 , Issue 2, 2018 Page 1

Worth the Weight: New International Guidelines Published for 

Manufacturing Load Cells

Byline: Jennifer Lauren Lee – Technical Contact: John Barton

Reprinted from: PML Impact, April 16, 2018

The revised OIML recommendation for the evaluation of load cells will affect the scales and balances used to weigh 

everything from people to grocery store bananas, and from blood pressure medications to cross-country shipments of 

goods.

At the heart of every electronic weighing instrument is a device called a load cell, which takes a mechanical force and 

turns it into an electronic signal. Anytime something needs to be weighed involving commerce – whether it’s lunch 

meat at a deli counter, or a truck crossing a bridge with a weight limit, or medicine being formed into pills with exactly 

the right proportions there is a good chance that there’s a load cell inside that scale or balance, making the measurement 

possible.

But before selling their products, companies that manufacture load cells need to ensure that their devices really do 

perform as intended. Most countries have a set of legal requirements that manufacturers must follow. The regulations 

that are adopted by many countries outside the United States1 have, as their basis a standard established by an 

intergovernmental organization called the International Organization of Legal Metrology (OIML).

Recently, a revised Recommendation (OIML documentary standard) for the metrological regulation of load cells –

referred to as R60 – was published by OIML. It’s the first update to the recommendation in 17 years.

John Barton of the National Institute of Standards and Technology (NIST) was the convener of the project group that 

revised the recommendation. This group comprised representatives from 26 of OIML’s member states.

Barton says that much of the revision work was focused on clarifying what is defined as a load cell since there are a 

number of technologies and designs that have been developed to quantify the force of gravity on an object in terms of 

its weight.

“Probably the biggest challenge we had in the revision was to define scope – how to be all-inclusive without 

discriminating against any particular technology,” Barton said. The vast majority of load cells in commercial devices 

use strain gauges, which convert physical stress into a measurable change in an electronic signal. But load cells can 

use other technologies as well, including pneumatic, hydraulic, or piezoelectric. “The project group spent a great deal 

of time defining the various categories of load cells based on their capabilities and, to some extent, the technologies 

used in their design,” Barton said.

Other changes to the recommendation were centered on updating the load cell-testing process, which is typically 

performed by laboratories on behalf of their member state governments. The OIML project group experts amended 

existing test procedures to expedite the process and added new procedures that would improve testers’ ability to 

evaluate how the devices respond to environmental influences, such as when exposed to electromagnetic fields during 

use.

The new revision also draws what Barton and his colleagues hope is a cleaner line between load cells and “complete 

weighing instruments,” which typically incorporate a load cell but are sold as units that include a readout of the weight. 

Complete weighing instruments are addressed under the OIML system in other recommendations, such as R76. 

Ideally, Barton said, manufacturers and testers don’t want a system where it’s unclear which OIML Recommendation 

applies to a device.

1 In the U.S., the regulation of commercial devices is based on a different set of requirements, adopted by the National 

Conference on Weights and Measures (NCWM). However, one of the goals of the NIST Office of Weights and 

Measures is to harmonize the OIML and U.S. standards whenever possible.
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Weights and Measures Connec�on, Vol. 9 , Issue 2, 2018 Page 2

As convener of the project group, Barton’s job included developing meeting agendas, scheduling and chairing those 

meetings, collecting group members’ input, incorporating their changes into subsequent drafts, and sending the revised 

document out for review. After receiving a set of comments, he would work them into a new draft and the cycle would 

start again. From beginning to end, the revision process took seven years. 

“It seemed like every time we had it nailed down, someone would ask a question – ‘What about this or that?’ – and 

we would 

Though consumers probably won’t notice changes to their electronic bathroom scales or the process of weighing their 

grocery store bananas, both domestic and international manufacturers of load cells are likely to be affected by the 

update, as well as the laboratories that test load cells before they are put on the market.