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5 things you need to know about weigh bridge accuracy

Factors including equipment mechanics, environment and vehicle affect weighing accuracy

Weight measurement firm AccuWeigh has offered advice on effective handling of weighbridges.
Weighbridges are an important tool to help transport operators and drivers ensure they are compliant with mass regulations to avoid damage to their vehicles and incurring penalties, the company says.
In Australia and New Zealand, weighbridges used for trade purposes are subjected to regular performance checks.
Earlier this year, VicRoads modified many of the self-serving weighbridges along some of the key rural freight corridors including Western Highway, Murray Valley Highway and Sturt Highway to feature external digital displays.
VicRoads says it encourages drivers to “proactively” check the weight of the vehicle and the load because it can be difficult to estimate the combined weight when carrying an unfamiliar load.
However, the accuracy of the weighbridge installation is as important as an operator’s need to follow the process.
Here, AccuWeigh outlines some of the key factors that affect the accuracy of weight measurement.
It highlights the fact that weight and mass information helps businesses across many operational aspects such as resourcing, invoicing and cost control.
According to AccuWeigh, these are the five most important factors to consider when considering investing in a weighbridge or understanding more about your existing installation:
Since all weighbridges operate with load cells, the quality of the equipment is as important as regular checks and recalibration to prevent mechanical variation errors and to ensure precision measurements and testing repeatability.
Temperature changes alter the sensitivity of the load cells and this can affect outputs.
If your weighbridge is to be installed in an area where there are significant variations in temperature, you should discuss how you can mitigate the effects of this with your weighbridge supplier.
Other environmental factors that can affect weighbridge accuracy include high and cross winds, humidity, vibration, a build-up of dirt, moisture and corrosion.
If the weighbridge uses stored data on empty vehicles to calculate the payload, then the readings will be affected by variables such as the fuel level of the truck, spare tyres, accessories (for example chains and tool boxes), the length of the truck and the weight of the driver.
Accuracy can also be compromised if the weighing system is subjected to a sudden, heavy load, such as when a load is dropped onto it or if the platform is knocked or disturbed.  Recalibration may then be necessary.
Human error
It can arise through supply of incorrect information by the driver of the vehicle or input by the bridge operator.
System errors
These can occur if there is interference with the electronic signal transmission (which can be caused by radio frequency interference, electromechanical interference, moisture and temperature) or if there are problems with the actual instrumentation and control devices.
“For optimum accuracy, it is imperative to take into consideration all factors that can affect the weighing system,” AccuWeigh suggests.
“The effect of these variables can be minimised by choosing a well-designed and high quality weighing system that is suited to your specific application and then ensuring that it is operated and maintained to the highest standards.”

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