Truck Scale Accuracy

Relying on Legal Tolerances Can Cost You Money

Weighing accuracy is easy to take for granted. You know that your truck scale is certified by a regulatory agency, so you assume that it weighs accurately. What you might not know is that accuracy levels that are acceptable to regulators could be costing you an unacceptable amount of money.

If you buy or sell truckloads of material by weight, your scale’s accuracy is important to your business. A truck scale used for this type of application is the equivalent of a cash register. It determines how much money the buyer is charged for a truckload of material. With every weighing error, you could be losing money.

Perfect weighing accuracy is hard to attain. The goal is usually to get as close to that target as possible. To ensure a reasonable level of accuracy, weights-and-measures authorities set maximum allowable errors for scales used in legal-for-trade applications. These scales are tested regularly to verify that they are within tolerance.

Testing is done with certified test weights. Any variation between a scale’s weight reading and the test weight placed on the scale is considered to be an error. If the error is greater than regulations allow, the scale must be adjusted to bring it within tolerance.

Legal tolerance

Can you feel confident that a certified truck scale is weighing accurately? When weights-and-measures authorities set a legal tolerance, they are saying that a certain amount of error is allowed. In their eyes, a scale with the maximum allowable error is just as acceptable as a scale that weighs with perfect accuracy. If you want to maximize profits, your target should be the highest accuracy possible; not just the legal tolerance.

The accuracy of your scale can make a big difference. For a single truckload, the maximum allowable error might not seem like much (see Figure 1). For a business that weighs a large number of trucks, the errors add up quickly.

Suppose the typical truck weighed on your scale transports 28 tons of material and has a gross weight of 40 tons. The weight reading could be 88 pounds (40 kilograms) below the actual weight and still be within the legal tolerance. If you weigh 100 trucks per day with this amount of error, you would be giving away a full truckload of material every seven days.

Preventing losses

How can you prevent these losses? You might try recalibrating the scale frequently to keep it close to the target weighing accuracy. Those constant service calls would require a considerable amount of time and money.

A better solution is to invest in digital technology that makes it easy to attain and maintain a high level of weighing accuracy. The POWERCELL® PDX® load cell uses a unique digital weighing technology that outperforms conventional analog technologies. Studies of field data from hundreds of truck scales demonstrate the ability of POWERCELL® PDX® load cells to hold a much tighter accuracy level than other load cells.

With POWERCELL® PDX® technology, it takes less time to certify a scale and the results are more accurate. Shift adjusting a truck scale equipped with analog load cells can be especially time-consuming. Because repeated adjustments are needed to fine-tune the scale, service technicians can spend a day or more trying to get close to their target accuracy. Shift adjusting a truck scale equipped with POWERCELL® PDX® load cells is an automated procedure performed by the scale terminal in a small fraction of that time.

A newly certified scale will not necessarily maintain its accuracy until the next scheduled recertification. Environmental forces such as temperature routinely affect weighing accuracy. As the temperature rises and falls, the weight signal produced by an analog load cell changes. In climates with extreme temperature changes, weighing errors can be significant.

Each POWERCELL® PDX® load cell is equipped with a microprocessor that tracks environmental conditions and adjusts the load cell output to compensate for changes. The truck scale maintains weighing accuracy by providing built-in compensation for temperature change, zero change, hysteresis, linearity, creep, and vibration.

Verified performance

The POWERCELL® PDX® load cell has a unique predictive diagnostics system that constantly monitors the performance of the entire load cell network. This system verifies network health and identifies any components that might need attention. Compare that with analog systems, which often hide problems for months.

A truck scale equipped with POWERCELL® PDX® load cells is easier to calibrate to a higher degree of accuracy, maintains accuracy longer, and alerts you if proactive service is needed. There is no better way to protect your profits against weighing errors.

How Costly Are Weighing Errors?

Don’t take your scale’s accuracy for granted. A scale that is not accurate can give away expensive material with every truck it weighs. You could be losing significant amounts of money without knowing it.

See for yourself

Learn more about weighing accuracy and how it affects your business’s profits. View the online webinar: Understanding Truck Scale Accuracy. Then find out how much money weighing errors can cost your business. Use the free allowable-error calculator to estimate the potential losses.