Kenya retires the old kilo for more accurate measurement

Kenya Bureau of Standards (Kebs) Director Metrology and Testing Dr Henry Rotich, Kebs acting MD Bernard Nguyo, International Organisation for Standardisation (ISO) president-elect Eddy Njoroge and National Standards Council Chairman Ken Wathome during the World Metrology Day 2019 celebrations last week. PHOTO | DIANA NGILA | NAIROBI MEDIA GROUP  

In Summary

• The kilo will now be defined using a fixed value of the Planck constant and will be maintained using a Kibble Balance.
• The redefinition will ensure it remains reliable, and enable far more accurate mass measurements in the future.

   

By DAILY NATION
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The change might be as insignificant as a strand of an eyelash to most people, but to scientists, it’s monumental.

Last week Kenya joined the world to retire the definition and use of the kilogramme (kg), as we have always known it, and adopted a more accurate unit of measuring mass.

Although in everyday life it will appear that not much has changed, the redefinition of the kilo will ensure it remains stable, and enable more accurate mass measurements in the future.

FIXED VALUE

Going forward, the kilo will now be defined using a fixed value of the Planck constant and will be maintained using a Kibble Balance, a device invented in the UK that measures mass using electromagnetic and quantum techniques.

The redefinition will ensure it remains reliable, and enable far more accurate mass measurements in the future.

On May 20, the World Metrology Day, the world said goodbye to the original kilogramme as the redefinition of the SI unit came into force.

The day is marked annually to celebrate the International System of Units. The date is the anniversary of the signing of the Metre Convention in 1875.

The redefined units are anticipated to bring benefits to citizens, including economic success resulting from the ability to manufacture and trade precisely made and tested products.

Speaking during the Metrology Day, acting Kebs managing director Bernard Nguyo said the changes will not be noticed by the man on the street and industries because there will be no net changes to the derived units.

KILOGRAM

One of the sectors that will benefit from this is health, where the medical board in a recent report said that some cases of medical negligence and malpractices were as a result of machine error. These errors, Kenya Bureau of Standards (Kebs) argued, resulted from use of uncalibrated medical equipment.

Retailers and manufacturers will also not need to replace or calibrate their scales.

“We’re not changing the mass weights used in our daily lives for measurements. We’re neither reducing the kilogramme nor adding it, but rather changing the way it’s realised at the apex. A kilo of unga will still remain one kilo,” Mr Nguyo said.

In November last year, scientists from more than 60 nations converged at the General Conference on Weights and Measures (CGPM) to redefine the kilogram, the base unit of mass in the International System of Units (SI).

METRIC SYSTEM

This change will revamp the base measurements for the metric system. For the first time, the system of measurements used in most countries,

will no longer be defined by specific physical objects.

“The revised SI future proofs our measurement system so that we are ready for all future technological and scientific advances such as 5G networks, quantum technologies, and other innovations that we are yet to imagine,” Richard Brown, Head of Metrology at the National Physical Laboratory, said in a press release.

For more than 100 years Paris, France, has been home to the ‘Le Grand K’, the International Prototype Kilogram (IPK), a block of metal that previously defined the weight of a kilogram.

WEIGHTS

Everything from kitchen scales to gym weights around the world was manufactured to the standard set by the cylinder of platinum iridium, which has been kept in a high-security vault in the French capital since 1889.

Different countries have their own ‘Prototype Kilograms’ that serve as national standards, which were calibrated to the Paris artefact.

In Kenya, the object that defined a kilogramme was kept in an underground bunker at the Kenya Bureau of Standards offices in South C.

The one-kilo metallic knob kept at Kebs is often sent to France for comparison against the global prototypes.

DAMAGE

But this cylinder in Kenya, just like the rest of the world, was found to be susceptible to damage and environmental factors, and is compared to its copies only once every 40 years, making calibration extremely difficult and inaccurate.

Tiny margins of error are acceptable when it comes to measuring a bag of sugar for example, but for sophisticated science more precise measurements are required.

International Organisation for Standardisation incoming president Eddy Njoroge underscored the role of measurements and its applications in the realisation of sustainable economic growth.

“Many ISO documented standards involve appropriate measurement. They thus rely on the ISO and quality infrastructure which provide a fundamental pillar for trade, scientific comparison, innovation and emerging technologies, technical cooperation and a basis for mutual recognition arrangements between governments,” Njoroge said.