Quantum Scale System
How the Percentage Tare Value is Calculated
Percentage Tare value is the value expressed as a percentage (e.g. 5.6%, 2.3%, etc.), that represents the proportion of tare material in comparison with the gross weight of a commodity. For example, if the percentage tare value for a specific individually wrapped confection is 14%, it means that for a gross weight of 100 grams, the total weight of individual wrappers is 14 grams.
The percentage tare value (Proportional Tare) is the figure that should be used to calculate the proper tare to be used when weighing individually wrapped confections (IWC).
Here is an example illustrating how it is calculated. In order to determine the net weight of candies, a fixed tare (weight of the cellophane bag and the twist tie) must first be deducted from the total gross weight.
Then, the weight of the individual wrappers must also be deducted. This weight is proportional to the number of candies in the bag. To determine this weight, two methods can be used: 1) candies are unwrapped and the individual wrappers are weighed, or 2) it is calculated using the percentage tare value (%T) and the gross weight.
The first method, which is a destructive method, should be used by the IWC manufacturers or importers to calculate the percentage tare value applicable to their products. This percentage tare value should then be provided to retailers so that they can use the second method which is non- destructive.
Method to be used by the manufacturer or importer for determining Percentage tare value (%T):
1)Ensure the scale is indicating zero (0).
2)Select a minimum sample of 25 candies.
3)Unwrap the candies, place the unwrapped candies aside for further weighing, and weigh the wrappers. The total weight of the wrappers must be at least ten times greater than the increment size (e.g. at least 20 grams if the scale has 2 gram increments). If not, unwrap more candies and add wrappers on the scale until the target weight is reached.
4)Record the total weight of the wrappers. This is the tare weight (TW).
5)Leave all the wrappers on the scale platter and add all the candies that were unwrapped. Weigh all wrappers and candies together and record this as the gross weight (GW).
6)Calculate the percentage tare value. %T = TW x 100%
GW
where:
%T = Percentage Tare Value TW = Tare Weight
GW = Gross Weight
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