{{refimprove, date=August 2010
A beltweigher or belt weigher is a piece of industrial control equipment used to gauge the mass or flow rate of material travelling over a troughed (cupped) conveyor belt of any length which is able to adequately contain the material being weighed. These are also known as belt scales, dynamic scales, conveyor scales, and in-motion weighers. Many such
check weigher
A checkweigher is an automatic or manual machine for checking the weight of packaged commodities.
It is normally found at the offgoing end of a production process and is used to ensure that the weight of a pack of the commodity is within specif ...
s or
feed weighers
Feed or The Feed may refer to:
Animal foodstuffs
* Animal feed, food given to domestic animals in the course of animal husbandry
** Fodder, foodstuffs manufactured for animal consumption
** Forage, foodstuffs that animals gather themselves, su ...
are an active part of the process flow control of the conveyor line.
A belt weigher replaces a short section of the support mechanism of the belt, which might be one or more sets of
idler
The Idler refers to someone idle:
* An idle game
* A slacker, a person who habitually avoids work
* Idler-wheel, a system used to transmit the rotation of the main shaft of a motor to another rotating device
* Idler circuit, a circuit in a paramet ...
rollers, or a short section of channel or plate. This weighed support is mounted on
load cell
A load cell converts a force such as tension, compression, pressure, or torque into an electrical signal that can be measured and standardized. It is a force transducer. As the force applied to the load cell increases, the electrical signal change ...
s, either pivoted, counterbalanced or not, or fully suspended. The mass measured by the load cells is integrated with the belt speed to compute the mass of material moving on the belt, after allowing for the mass of the belt itself. Belt weighers generally include the necessary electronics to perform this calculation, often in the form of a small industrialized
microprocessor
A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...
system.
A belt weigher is normally mounted in a well supported straight section of belt, with no vertical or sideways curvature, and as close to level as is practicable. The weighed support must be aligned vertically and horizontally with the adjacent supports to avoid tensile forces in the belt skewing the measurement.
Due to the belt tension variation, frequent check calibration must be done.
Outputs from belt weighers are typically:
* pulses at predefined increments of mass
* an analogue signal proportional to the flow rate
In addition, some belt weigher controllers will offer features such as driving an output to stop the belt when a predefined mass of material has been measured, or a range of alarms to indicate nil flow, belt slippage and belt stoppage.
Uses include mineral and aggregate extraction, continuous mixing processes, control of
variable rate feeder
A variable rate feeder (often shortened to belt feeder, or simply feeder) is a piece of industrial control equipment used to deliver solid material at a known rate into some process.
Belt feeders vs. belt conveyors
In both form and function, ...