1. OIML RECOMMENDATION R87 TARE DETERMINATION Ben Aitken Trading Standards Officer Trading Standards MBIE New Zealand Kevin Gudmundsson Legal Metrology Advisor Trading Standards MBIE New Zealand

2. OIML Recommendation R87 Tare Procedures Annex B OIML R87 (Informative)

3. Tare Procedures R87 procedures permit the use of: 1.Unused dry tare 2.Used dry tare Tare weight = term for weight of the packing material

4. Tare Procedures Procedures permit the use of: 1. Unused dry tare – the weight of unused packing material of one pre- package. Empty packaging material supplied by the packer.

5. Tare Procedures Procedures permit the use of: 2. Used dry tare – packing material that has been used as part of a pre- package and that has been separated from the product and cleaned using normal household procedures used by consumers of the product – (e.g. the material should not be dried in an oven).

6. Tare Procedures 2. Used Dry Tare – In practise packaging material used for wet products such as chicken and other meats can be difficult to dry. With these products it is often best to wash the packaging material and dry with a cloth then allow it to dry overnight.

7. Tare Procedures Tare weight includes the weight of all of the packing material

8. Tare Procedures Determine the actual quantity of product in the pre- package as follows: Actual Quantity of Product = Weight of the Prepackage –Average weight of the packing material The average weight of the packing material is referred to as the average tare weight (ATW).

9. Tare Procedures Average Tare Weight – ATW Table B.1 Tare

10. Tare Procedures

11. Determine the unused dry tare or the used dry tare. 1.Randomly select an initial sample of 10 packing materials. – These can be taken from an inspection lot (used dry tare) or from a lot of packing materials at the point of pack (unused dry tare). – Note: in practise it is recommended to use unused dry tare if at all possible.

12. Tare Procedures 2.Determine the individual weight of each of the 10 packing material 3.Record the Nominal Quantity of the goods as labelled by the packer 4.Using Table 2 (R87) determine the amount of error allowed (T)

13. Tare Procedures Table 2 (R87) - determine the amount of error allowed (T) Nominal quantity of product (Q n ) in g or ml Tolerable Deficiency (T) a Percent of Q n Tolerable Deficiency (T) a g or ml 0 to 509- 50 to 100-4.5 100 to 2004.5- 200 to 300-9 300 to 5003- 500 to 1000-15 100 to 10 0001.5- 10 000 to 15 000-150 15 000 to 50 0001- a T values are to be rounded up to the next 1/10 of a g or mL for Q n ≤ 1000 g or mL and to the next whole g or mL for Q n > 1000 g or mL.

14. Tare Procedures 5.Determine the average tare weight (ATW) and the standard deviation (s)

15. Tare Procedures Example Tare Procedure – Exercise

16. Tare Procedures

17. Nominal Weight = 500g 10% of Nominal Weight = 50 g ATW = 4 g 4 is ≤ 10% 500 g Use Average Tare Weight Tare SampleTare Weight (g) 1 3 2 4 3 4 4 3 5 4 6 5 7 4 8 4 9 5 10 4 ATW4 Standard Deviation (s)0.66

18. Tare Procedures

19. Scenario 2 We calculate the ATW of our 10 packing material’s and it is >10% of the nominal quantity

20. Tare Procedures

21. Scenario 2 Nominal Quantity (Qn) = 180 g ATW (10 packing materials) = 45.1 g 10% of Qn = 18 g ATW > 10% Qn (45.1 > 18) We now need 1.To determine standard deviation of 10 packing material weights, and 2.To determine T (from Table 2 of R87)

22. Tare Procedures Table 2 - Tolerable deficiencies in actual content for prepackages Nominal quantity of product (Q n ) in g or ml Tolerable Deficiency (T) a Percent of Q n Tolerable Deficiency (T) a g or ml 0 to 509- 50 to 100-4.5 100 to 2004.5- 200 to 300-9 300 to 5003- 500 to 1000-15 100 to 10 0001.5- 10 000 to 15 000-150 15 000 to 50 0001- a T values are to be rounded up to the next 1/10 of a g or mL for Q n ≤ 1000 g or mL and to the next whole g or mL for Q n > 1000 g or mL.

23. Tare Procedures Scenario 2 Nominal Quantity (Qn) = 180 g ATW (10 packing materials) = 45.1 g 10% of Qn = 18 g T = 4.5% of Qn (180*4.5%) T = 8.1 g 0.25 x T = 2.025 s = 0.737 In this instance s < 2.025

24. Tare Procedures Nominal weight (Qn) = 180 g T = 8.1 g 10% of Nominal weight = 18 g Average tare = 45.1 g s = 0.738 ATW > 10% of Nominal weight (45.1 > 18 g) s < 0.25 x T 0.25xT = (0.25 x 8.1 = 2.025) Use ATW of 25 packages Tare sampleTare weight (g) 1 45 2 46 3 44 4 45 5 6 46 7 45 8 44 9 46 10 45 Mean45.1 s0.738

25. Tare Procedures

26. The sample number is increased to 25. Use the original sample of 10 packages and select a further 15. Use the ATW of the 25 packages. Consider whether such action is common sense – e.g. where the weight of the packaging is greater than it’s contents, such as with small tubes of ointment, but the tare weight is very constant, there is nothing to be gained from checking a further 15.

27. Tare Procedures

28. Scenario 3 We calculate the ATW of our 10 packing material’s and it is >10% of the nominal quantity and The standard deviation (s) is greater than 0.25 x T

29. Tare Procedures

30. If the average tare weight of the initial tare sample is greater than10% of the nominal quantity and the standard deviation is greater than 0.25 x T an ATW cannot be used. – In this case it is necessary to determine every individual tare weight.

31. Tare Procedures Nominal weight = 45 kg T = 0.45kg 10% of Nominal weight =4.5kg Average tare = 34.85 kg s = 0.215 ATW > 10% of Nominal weight (34.85 > 4.5 kg) s > 0.25 x T (0.25 x 4.5 = 0.1125 kg) Use individual tare weights Tare sampleTare weight (kg) 1 34.6 2 34.9 3 35.1 4 35.3 5 34.7 6 34.9 7 34.5 8 34.7 9 34.8 10 35.0 Mean34.85 s0.215

32. Tare Procedures

33. Non Average Tare Weight 1.Non-destructive Testing 2.Destructive Testing

34. Tare Procedures Non Average Tare Weight A Legal Metrology Official should always look to avoid destroying the manufacturers product, especially if it is high value. In some instance destructive testing may be unavoidable

35. Tare Procedures Non Average Tare Weight Non-destructive testing Non-destructive testing may be achieved at the packers premises by pre-weighing the packaging material before it is filled

36. Tare Procedures Non Average Tare Weight Pre-weighed packing material must be easily identifiable, consider using colour coding – A sequence of coloured ribbon or elastic bands The unique tare weight of each packing material must be recorded before it is filled – Consider using adhesive labels and recording the tare on the package itself

37. Tare Procedures Non Average Tare Weight Place each pre-weighed packing material on the production line at randomly generated time intervals This method generally involves additional personnel It is advisable to include additional samples on the production line just in case some are missed

38. Tare Procedures Non Average Tare Weight This may be desirable in the case of small necked bottles with dense products in them. Emptying the product from these type bottles, then washing and drying them can be very awkward and time consuming.

39. Tare Procedures Non Average Tare Weight Destructive Testing Pre-packages have to be opened to determine compliance. Often involves handling of the product which may render it unsalable May be the only option for some types of goods – e.g. Frozen food goods

40. Tare Procedures Non Average Tare Weight Destructive Testing Packaging material for the tare test may be obtained by: – Co-operation of the packer or importer – Seizing goods if satisfied on reasonable grounds that an offence has been committed – Arranging to purchase from the packer

41. Tare Procedures Thank you for your attention Any Questions?

42. Calculating Error Calculate error for rice exercise Gross – ATW = Actual Quantity Actual Quantity – Q n = Error

43. Calculating Error Gross – ATW = Actual Net Quantity Actual Net Quantity – Qn = Error No.GrossATWNetQnError 15054501500+1 25054501500+1 35054501500+1 45044500 0 55054501500+1 65014497500-3