TS–011 General sealing requirements for weighing and measuring instruments

This policy specifies the sealing requirements applicable to weighing and measuring instruments that have been issued with a Certificate of Approval.

Reference documents


Instruments must be sealed in accordance with the requirements as specified in the Certificate of Approval or subsequent notifications issued by Trading Standards. This includes but is not limited to the following areas:

  • Head-work calibration points
  • Counter scale calibration points
  • The connection points between the junction box, load-cells and the indicator shall be secured by sealing to prevent the changing of the components without the breaking of seals (unless the cables from the junction box or load-cells are hard wired into the indicator housing).
  • Where Interface Ports (e.g. RS 232 Ports) are present on an indicator or weighing/measuring equipment and there is a possibility to manipulate data or weighing/measuring performance/characteristics then such interface ports shall be secured and sealed.
  • Head-work event counter functions where a calibration is performed, then the event counter number post calibration shall be recorded on a self-destructible adhesive label and attached to the equipment in an easily visible position.
  • All points where components may be dismantled or adjusted affecting any metrological characteristic of the equipment.
  • Any test points such as air eliminator test valves, etc.

The most appropriate means of sealing* depending on the situation may be used, this may include; sealing wire with lead seals, plastic seals or self-destructible labels. All seals must show the AP Identifiers, consisting of the letters “AP” and an “identification number”.

* Prior approval from Trading Standards is required before using any alternative method of sealing, other than that which is prescribed in the Certificate of Approval or detailed in the Quality Management System for the accredited organisation.

Trade Measurement — Technical Policy

Policy number: TS - 011
Effective date: July 2016
Version date: October 2016
Version number: 2
Policy name: General sealing requirements for weighing and measuring instruments
Reviewed by: Davis White, Legal Metrology Advisor and Senior Trading Standards Officer
Approved by: Phil Sorrell, Team Leader Compliance and Inspection