Weighing Scale Terminology- Part 5


Gross Weight – The total weight of the object being weighed including its vehicle, packaging, or container. Gross weight is typically required for calculating the shipping or transportation charge.

Net Weight – The weight of an object being weighed, discounting the weight of its vehicle, packaging, or container. Net weight is useful for calculating the charge, tax, or payment required for items.

Tare Weight – The weight of an empty vehicle, package, or container. Tare weight is sometimes written on the outside of railcars or shipping and packing containers for quick determination of the net weight during weighing operations.

Average Piece Weight (also APW) – On counting scales, this is determined by dividing the weight by the number of samples on the platform. Counting scales work on the assumption that the parts being counted are all of uniform weight.

Tare Mechanism – A mechanism (including a tare bar) designed for determining or balancing out the weight of packing material, containers, vehicles, or other materials that are not intended to be included in net weight determinations. Most electronic scales have a tare button or feature which is used to reset the display value to zero when a container is placed on its load-receiving element. If the vehicle or container is then filled, the displayed weight will be that of the contents alone (see Net Weight). If the vehicle or container and its contents are removed from the scale, a negative weight value is typically displayed equal in absolute value to the Tare Weight.

Zero-Setting Mechanism – Means provided to attain a zero balance indication with no load on the load-receiving element. Three types used in scales are:

  • Automatic Zero-Tracking Mechanism (also Auto Zero) – Automatic means provided to maintain the zero balance indication within certain limits, without intervention of an operator. Environmental conditions as well as internal noise on the circuit can cause the scale’s display to drift. The auto zero feature helps to eliminate these unwanted changes in display output and insures that the scale is properly zeroed before each weighing. However, the auto zero feature can be a problem when trying to weigh very small amounts that within the auto-zero range. For instance, if a scale has an auto-zero range of 0.2g and you place less than 0.2g on the scale, the display will not change.

  • Manual Zero-Setting Mechanism – Nonautomatic means provided to attain a zero balance indication by the direct operation of a control.

  • Semiautomatic Zero-Setting Mechanism – Automatic means provided to attain a zero balance indication requiring a single initiation by an operator.

Span – The distance between adjoining sections of a scale.