TARE DETERMINATION Ben Aitken Trading Standards Officer Trading Standards MBIE New Zealand Kevin Gudmundsson Legal Metrology Advisor Trading Standards MBIE New Zealand OIML Recommendation R87 ID: 552392
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Slide1
OIML RECOMMENDATION R87
TARE DETERMINATION
Ben Aitken
Trading Standards OfficerTrading Standards MBIENew Zealand
Kevin Gudmundsson
Legal Metrology Advisor
Trading Standards
MBIE
New ZealandSlide2
OIML Recommendation R87
Tare Procedures
Annex B OIML R87 (Informative)Slide3
Tare Procedures
R87 procedures permit the use of:
Unused dry tare
Used dry tare
Tare weight = term for weight of the packing materialSlide4
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.Slide5
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).Slide6
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.Slide7
Tare Procedures
Tare weight includes the weight of
all
of the packing materialSlide8
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).Slide9
Tare Procedures
Average Tare Weight – ATW
Table B.1 Tare Slide10
Tare ProceduresSlide11
Tare Procedures
Determine the unused dry tare or the used dry tare
.
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.Slide12
Tare Procedures
Determine the individual weight of each of the 10 packing material
Record the Nominal Quantity of the goods as labelled by the packer
Using
Table 2 (R87)
determine the amount of error allowed (
T
)Slide13
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 50
9
-
50 to 100
-
4.5
100 to 200
4.5
-
200 to 300
-
9
300 to 500
3
-
500 to 1000
-
15
100 to 10 000
1.5
-
10 000 to 15 000
-
150
15 000 to 50 000
1
-
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.
Slide14
Tare Procedures
Determine the average tare weight (ATW) and the standard deviation (
s
)
Table B.1 Tare
If
Then
The ATW is ≤ 10 % of the nominal quantity of product
Use the ATW to determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity and
s < 0.25 x T
Use a total of 25 packages to compute the ATW and determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity
and s > 0.25 x T
An ATW cannot be used. It is necessary to determine and to consider every individual tare weight.
Determine the actual quantity of product in each pre-package according to A.2 step 7Slide15
Tare Procedures
Example Tare Procedure –
ExerciseSlide16
Tare ProceduresSlide17
Tare Procedures
Nominal Weight = 500g
10% of Nominal Weight = 50 g
ATW = 4 g
4 is ≤ 10% 500 g
Use Average Tare Weight
Tare Sample
Tare Weight (g)
1
3
2
4
3
4
4
3
5
4
6
5
7
4
8
4
9
5
10
4
ATW
4
Standard Deviation (s)
0.66Slide18
Tare Procedures
Table B.1 Tare
If
Then
The ATW is ≤ 10 % of the nominal quantity of product
Use the ATW to determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity and
s < 0.25 x T
Use a total of 25 packages to compute the ATW and determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity
and s > 0.25 x T
An ATW cannot be used. It is necessary to determine and to consider every individual tare weight.
Determine the actual quantity of product in each pre-package according to A.2 step 7Slide19
Tare Procedures
Scenario 2
We calculate the ATW of our 10 packing material’s and it is >10% of the nominal quantity
Slide20
Tare ProceduresSlide21
Tare Procedures
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 To determine standard deviation of 10 packing material weights, andTo determine T (from Table 2 of R87)Slide22
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 50
9
-
50 to 100
-
4.5
100 to 200
4.5
-
200 to 300
-
9
300 to 500
3
-
500 to 1000
-
15
100 to 10 000
1.5
-
10 000 to 15 000
-
150
15 000 to 50 000
1
-
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.
Slide23
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 g0.25 x T = 2.025s = 0.737In this instances < 2.025Slide24
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
0.25x
T
= (
0.25 x 8.1 = 2.025)
Use ATW of 25 packages
Tare sample
Tare weight (g)
1
45
2
46
3
44
4
45
5
45
6
46
7
45
8
44
9
46
10
45
Mean
45.1
s
0.738Slide25
Tare Procedures
Table B.1 Tare
If
Then
The ATW is ≤ 10 % of the nominal quantity of product
Use the ATW to determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity and
s < 0.25 x T
Use a total of 25 packages to compute the ATW and determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity
and s > 0.25 x T
An ATW cannot be used. It is necessary to determine and to consider every individual tare weight.
Determine the actual quantity of product in each pre-package according to A.2 step 7Slide26
Tare Procedures
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.
Slide27
Tare ProceduresSlide28
Tare Procedures
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
TSlide29
Tare ProceduresSlide30
Tare Procedures
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.
Slide31
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 sample
Tare 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
Mean
34.85
s
0.215Slide32
Tare Procedures
Table B.1 Tare
If
Then
The ATW is ≤ 10 % of the nominal quantity of product
Use the ATW to determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity and
s < 0.25 x T
Use a total of 25 packages to compute the ATW and determine the actual quantity of product in the pre-packages according to A.2 step 7.
The ATW is > 10 % of the nominal quantity
and s > 0.25 x T
An ATW cannot be used. It is necessary to determine and to consider every individual tare weight.
Determine the actual quantity of product in each pre-package according to A.2 step 7Slide33
Tare Procedures
Non Average Tare Weight
Non-destructive Testing
Destructive TestingSlide34
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 unavoidableSlide35
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 Slide36
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 filledConsider using adhesive labels and recording the tare on the package itself Slide37
Tare Procedures
Non Average Tare Weight
Place each pre-weighed packing material on the production line at randomly generated time intervalsThis method generally involves additional personnel
It is advisable to include additional samples on the production line just in case some are missed Slide38
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.Slide39
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 goodsSlide40
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 Slide41
Tare Procedures
Thank you for your attention
Any Questions?Slide42
Calculating Error
Calculate error for rice exercise
Gross – ATW =
Actual
Quantity
Actual
Quantity
–
Q
n
= ErrorSlide43
Calculating Error
Gross – ATW = Actual Net QuantityActual Net Quantity – Qn
= Error
No.
Gross
ATW
Net
Qn
Error
1
505
4
501
500
+1
2
505
4
501
500
+1
3
505
4
501
500
+1
4
504
4
500
500
0
5
505
4
501
500
+1
6
501
4
497
500
-3Slide44