UKWF Technical Articles

1.1 Regulated Purpose

If a non-automatic weighing instrument is used for one of the following  purposes it will then need to be initially verified or re-qualified where necessary before it can be used, equally, if it is not used for one of the regulated purposes it will not need to be initially verified or re-qualified. If the customer would like the accuracy of an instrument that is not used for a regulated purpose to be determined this should be done in line with the UKWF Calibration Code of Practice

(a)        Determination of mass for commercial transactions;

This is the application that we will most often see in our day to day work and will include the

traditional buying and selling by weight between consumers and traders and business to business transactions; it will include such things as jewelers, scrap metal merchants, and post office scales amongst a wide range of other possible transactions It would also include the situation of a client using an instrument to check the quantity of a product from a supplier. If, in the event of a discrepancy between the customers weights and the supplier’s weights, if it is the customers scale that is used to determine the final weight, that scale will need to be initially verified

(b)       Determination of mass for the calculation of a toll, tariff, tax, bonus, penalty, remuneration, indemnity or similar type of payment

This would include any weighing equipment that is used to determine a fee such as the scale that may be used to weigh lorries on to ferries or waste going to landfill. It could also include such things as instruments used to determine the wages for workers picking fruit

(c)        Determination of mass for the application of laws or regulations or for an expert opinion given in court proceedings;

This would include any weighing equipment used for law enforcement such as a road traffic weighbridge.  Other interesting examples that fall under this category would be scales that are used in coroner’s enquiries, and scales covered by safety legislation where a weight declaration is required. An example of this would be the SOLAS (Safety of Life at Sea) Requirements. This is an International Treaty to which the UK is party which creates a legal obligation for the weight of all goods that are intended to be shipborne cargo to have the weight declared by the shipper before they are loaded. Similarly, The Air Operations Regulations requires the weight of passengers and baggage to be determined before flying from a heliport. Any scales in use for these purposes, will be covered by this requirement.

(d)       Determination of mass in the practice of medicine for weighing patients for the purposes of monitoring, diagnosis and medical treatment

This covers a wide range of instruments that can be found in all aspects of medicine. The weighing does not need to be completed by a medical practitioner. These instruments will also be covered by the Medical Devices Regulations 2017/745. They will invariably be found in hospitals but also doctor’s surgeries and use in the community by such people as midwives and health visitors

(e)        Determination of mass for making up medicines on prescription in a pharmacy and determination of mass in analyses carried out in medical and pharmaceutical laboratories;

This relates to the use of weighing instruments in the making of medicines.

(f)        Determination of price on the basis of mass for the purposes of direct sales to the public and the making up of pre-packages;

The important point of this clause is that instruments used for the making up of pre-packages are controlled. These will be non-automatic weighing instruments that are used by packers for making up or checking of packages for the Packaged Goods Regulations[1]

What is the difference between a NAWI and an AWI?

The general difference between the two is that a NAWI requires the intervention of an operator during the weighing process, for example to deposit on or remove from the load receptor the load to be measured and also to obtain the result.

However, it is not always easy from the above brief definition to determine which requirements the instrument has to meet. In these situations, the following interpretation (taken from section 3.1.9 of WELMEC Guide 2, 2015 of the definition of a NAWI or an AWI should be used only when doubt exists in applying the definitions contained in EC Directive 2014/31/EC and the relevant OIML recommendations.

“An instrument capable of performing consecutive weighing cycles without any intervention of an operator is always regarded to be an AWI. If an instrument needs the intervention of an operator, it is regarded to be an NAWI only in the case where the operator is required to determine or verify the weighing result.

Determining the weighing result includes any intelligent action of the operator that affects the result, such as deciding when an indication is stable or adjusting the weight of the weighed product.

Verifying the weighing result means making a decision regarding the acceptance of each weighing result on observing the indication. The weighing process allows the operator to take an action which influences the weighing result in the case where the weighing result is not acceptable.

Note: the necessity to give an instruction to start the weighing process or to release a load is not relevant in deciding the category of instrument.”

Automatic Weighing Instruments

For automatic weighing instruments the definitions in the Weights and Measures Act 1985 still applies.

Section 7 of the Act says:

7. “Meaning of ‘use for trade’

(1)        In this Act ‘use for trade’ means, subject to subsection (3) below, use in Great Britain in connection with, or with a view to, a transaction falling within sub-section (2) below where –

(a)        the transaction is by reference to quantity or is a transaction for the purposes of which there is made or implied a statement of the quantity of goods to which the transaction relates, and

(b)        the use is for the purpose of the determination or statement of that quantity.

(2)        A transaction falls within this subsection if it is a transaction for –

(a)        the transferring or rendering of money or money’s worth in

consideration of money or money’s worth, or

          (b)        the making of a payment in respect of any toll or duty.

(3)        Use for trade does not include use in a case where –

(a)          the determination or statement is a determination or statement of the quantity of goods required for dispatch to a destination outside Great Britain and any designated country, and
(b)          the transaction is not a sale by retail, and
(c)          no transfer or rendering of money or money’s worth is involved other than the passing of the title to the goods and the consideration for them.”

Any automatic weighing instruments that are used in applications that fall under the definition of use for trade as set out in Section 7 need to have a type examination certificate and be verified before they can be used for trade. The one exception to this is automatic checkweighers which do not need to be approved.

[1] The Weights and Measures (Packaged Goods) Regulations 2006- Regulation 9

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