Continuous weighing of granular material as it is carried along a conveyor belt can offer economic advantages to management in process control, stock control and in accounting, but only if accuracies can be guaranteed to fall within a specific tolerance, typically better than ±1/2% full scale deflection. Apart from neglect of belt weigher manufactures' recommended operating procedures, the more obvious sources of inaccuracy in commercial installations are:
- Poor calibration techniques.
- Poor installation.
- Misalignment of idler-sets on the weigh scale and of threshold idler-sets, so that the effective weigh-length varies according to the load on the belt.
- Poor belt tracking or lateral variation of belt position on idler-sets.
- Poor installation and positioning of belt speed sensors so that the measurement does not the actual weigher length.