Insights

Calibrating Scales & Compliance: Why Accuracy Protects the Value Chain

Details: Published: Thursday, 11 December 2025 17:00

Our scales don’t lie, and we’ll tell you why.

As a buy-back centre owner or waste collector, you know what it means to put your material on the scale. Your day or weeks’ worth of work becomes a number, and that number decides your earnings.

That is why accuracy matters. Mpact Recycling’s scales do not lie. They are calibrated twice a year by South African National Accreditation System (SANAS) accredited technicians, verified under the Legal Metrology Act and maintained to meet the standards required for trade. When people’s livelihoods depend on a reading, there is no space for guesswork. In this blog we unpack what the legislation requires, how scale calibration works and why keeping our scales accurate is one of the most important commitments we make to the value chain.

What does it mean to calibrate a scale

Calibration is the process of checking whether a scale is still accurate. With dust, vibration and heavy use, a scale slowly drifts off its true reading. A technician uses certified test weights to see if the number on the screen matches the real weight. If it doesn’t, they adjust the scale until it is correct again. Without calibration, a scale will drift further and eventually pay people for less or more than they delivered.

There is legislation to support calibrated scales

The South African Legal Metrology Act, Act 9 of 2014, sets the rules for any scale used to buy or sell goods by weight. It exists to protect both sides of the transaction. It prevents businesses from using inaccurate or tampered scales and it gives waste collectors and suppliers the right to demand proof that the readings are legitimate.

In simple terms, the law says that if you are paying or being paid per kilogram, the scale must be accurate, verified and kept that way. Calibrated scales are not just good business. They are a legal requirement designed to protect everyone in the value chain.

Here is how to check whether a buyer has calibrated their scales:

Ask your buyer if their scale has been verified by a SANAS accredited technician.
Only accredited service providers can test and certify a trade scale. Anything else is not recognised under the Legal Metrology Act.
Look for a valid verification certificate.
A compliant scale must display a current verification sticker and have the certificate available on site. Suppliers and waste collectors have the right to ask for it at any time.
Ask how often their scales are calibrated.
Scales lose accuracy through heavy loads, daily use and site conditions. Regular calibration keeps them within the limits required for trade. A responsible buyer should know when their last calibration took place and when the next one is scheduled.

We calibrate our scales twice a year for our suppliers

The scale and the weighbridge are two of the most direct ways we engage and transact with suppliers and waste collectors. Every reading carries weight. That is why we invest the time and money to calibrate our scales twice a year across all branches.

The law sets the minimum standard, but we go further because accuracy protects the people who depend on us. With thousands of suppliers and waste collectors walking through our 14 branches nationwide, accuracy is not optional. You should never have to question the number on the screen.

The scales you’ll find at our branches

Mpact Recycling branches use two main types of trade-approved weighing systems:

Weighbridges.
Large industrial scales built into the ground. Trucks drive on full and then empty, and the difference gives the exact weight of the recyclables.
Platform scales.
Heavy-duty flat scales used for bags, bales and smaller loads. Waste collectors and bakkie brigades use them every day.

Both systems use load cells. These are small metal components that measure weight by detecting tiny amounts of pressure. They are precise, but they are sensitive to dust, vibration, heat, cold, heavy use and even how the material is placed. Over time these small factors cause the reading to drift. That drift does not fix itself. It gets worse. A small error becomes a bigger one, and eventually the scale can be out by a full kilogram or more. Calibration is the only way to reset the system and make sure the scale is telling the truth.

How Mpact Recycling and the industry calibrate their scales

Mpact Recycling uses SANAS-accredited service providers to calibrate and verify both weighbridges and platform scales. The process follows a standard method recognised under the Legal Metrology Act.

Zero check.
The technician ensures the scale reads zero before testing begins.
Certified test weights.
Legally certified calibration weights or test vehicles are applied. These weights have traceable certification.
Testing across load points.
The scale is tested in stages to ensure accuracy from low loads to full capacity.
Repeatability test.
Weights are added and removed several times. The readings must remain consistent.
Adjustments if needed.
' If the scale is outside acceptable limits, the technician adjusts the calibration settings until the readings are correct.
Verification sticker applied.
A dated, official sticker is placed on the scale, supported by a verification certificate.
Calibration report issued.
Each branch receives a full report with results and the next due date.

Calibrated scales protect the circular economy

We calibrate our scales not only because the law requires us to do so but because accuracy protects the people who keep the circular economy moving. A fair reading leads to a fair payment. A fair payment builds trust. And trust strengthens the entire value chain from the waste collector to the mill.

This is why we verify our equipment, recalibrate it and maintain it long before errors appear. It is our responsibility to make sure that every kilogram is accounted for and that every supplier is paid for the full value of their work.

Visit an Mpact Recycling branch and see how we weigh, record and pay with complete transparency.