Approved Average Weight Equipment
Average weight has now been in operation since 1980, and introduced to allow volume packers (i.e. 454g bags of sugar x 10000 items per batch) and statistically check the batch by take a small % of packs and make appropriate records to ensure they are compliant with the Under the average weight system the packer or importer is responsible for ensuring that the goods they pack are to the three packers' rules.
The actual contents of all the packages produced shall not be less, on average,than the nominal (marked) quantity.
The proportion of packages which are short of the stated quantity by a defined amount which equates to 2.5% or 1:40 (T1 Table)
No package should be short by more than twice the TNE. (T2)
To put it simple terms, if the batch produced on a day leaves your premisis, and say the mean weight is below the nominal stated in the package, or the number of permissable T1 violations present or there are ANY T2 packages in that batch made available for sale to consumers your filling process is not working and as you are legally liable.
In 2006 UK weights and measures reduced the batch quantity and simplified the regulations making EC average weight available to smaller producers, but most new packers are unaware that it's their companies legal requirements.
Your local trading standards are responsible that your process and sampling methods you are using is sufficiently accurate for your process to be tested, this must take into account variables in processes (standard deviation), tare variables,density etc.