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Understanding Long-Term Truck Scale Performance
Long-Term Accuracy Performance by Load Cell Technology
Like all calibrated measuring devices, truck scale accuracy will drift over time. Common factors that affect scale accuracy drift over time are: • High frequency dynamic mechanical loading: ≥80,000 lb trucks, 100+ times per day • Material buildup under the scale • Temperature changes
The following statistics were gathered from 50,000+ in-field service tests which used 20,000 to 25,000 lb test loads. The projected error on a fully loaded truck is nearly linear to the long-term tested error. Below are the statistical results by load cell technology type:
• Electrical degradation due to moisture • Sensor (load cell) technology type
Long-term service statistics show that truck scales drift between the typical semi-annual preventive maintenance and re-calibration. For example, in-use accuracy tests find 25% of the most common type of truck scales with legacy strain-gauge analog load cell technology are weighing outside of legal-for-trade tolerances. This is based on 10,000+ as-found accuracy tests. A large statistical sample of as-found accuracy data gives the customer an accurate assessment of the expected long-term accuracy performance of a truck scale. The following charts use this data to highlight the superior and consistent accuracy of POWERCELL based technology as compared to Analog.
Analog Load Cells
POWERCELL Sensors Hydraulic Load Cells
Nr. of test records
12,984
28,799
662
Nr. outside legal tolerance
28 %
8 %
13 %
2 Std. Deviations (95%)
+/- 472 lb
+/- 172 lb
+/- 550 lb
As found Tolerance for Analog Truck Scales
25% outside of legal tolerance
Operational Cost of Scale Inaccuracy
Proper maintenance and calibration testing is critical to ensuring the truck scale is performing accurately and legally. The potential operational costs of scale inaccuracy can be significant in terms of lost material, measuring operational efficiency, and customer confidence. Below are examples of potential costs of missing material with just a small-scale error.
Operational Cost of Scale Inaccuracy: 100 fully loaded trucks per day on a scale weighing 100 lb, under per load
As found tolerance (kg) From 12,980 Service Records
Price per ton Price per lb ($ / lb)
1 Day Loss 1 Week Loss 1 Month Loss 1 Year Loss
Bulk Material
As found Tolerance for POWERCELL Truck Scales 7% outside of legal tolerance
Crushed stone fill $ 20.00 / t
$ 0.01
$ 100
$ 500
$ 2.200 $ 26.400
Cement
$ 60.00 / t
$ 0.030 $ 300
$ 1.500
$ 6.600 $ 79.200
Waste (MSW)
$ 50.00 / t
$ 0.025
$ 500
$ 2.500 $ 11.000 $ 132.000
Baled Cardboard $ 70.00 / t
$ 0.0350 $ 700
$ 3.500 $ 15.400 $ 184.00
Estimating the potential cost of scale inaccuracy for your operation is an important element of quantifying the total cost of ownership and return on investment for a truck scale capital asset. In summary, the impact of scale accuracy is extremely important for businesses. Sites processing high volumes of trucks or goods of considerable value should be particularly aware of their scales’ accuracy.
As found tolerance (kg) From 28,800 Service Records
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