USE IN "APPROVED" APPLICATIONS

The term "approved" applies whenever the weighing application is intended to be used for "legal-for-trade" weighing - that is, money will change hands according to the weight result. Such applications are bound by the legal metrology regulations of the relevant governments around the World, but most countries will comply with either the relevant EN's (Euro Norms) or the relevant OIML (Organisation Internationale de Metrologie Legale) recommendations.

• The LDU 68.1, LDU 69.1 LDU 78.1 and LDM88.1 has been approved as a component for use in weighing systems according to OIML recommendation R76. This approval will allow the use in approved weighing systems throughout Europe, and in many other countries of the World

To achieve approval on a particular application, it will be necessary to satisfy the relevant Governmental Trading Standards Authority that the requirements of the various rules and regulations have been satisfied. This task is greatly simplified if the key components of the weighing system, namely the load cells and the weighing indicator or digitiser, are already approved as "components".

Usually, a discussion with the Weighing Equipment Approvals Officers at the relevant National Weights & Measures Office will then reveal the extent of any pattern testing that may be necessary to ensure compliance.

Restrictions upon usage when in "Approved" applications

A number of performance restrictions must come into force. These restrictions are the number of display divisions, which become limited to 5000 divisions, and the sensitivity per display division, which becomes 0.7uV per division.

Once installed in the application, an "approved" application will require "stamping" by an Officer of the relevant Governmental Trading Standards Department. This certifies the equipment or system as being in accordance to the relevant regulations and within calibration limits.

The Traceable Access Code (TAC)

The user software must then provide a guard against improper access of the calibration commands (see the "Calibration Commands" section). The LDU 78.1 digitiser features the "Traceable Access Code" or TAC method of controlling the access to the calibration commands group. This means that a code is maintained within the device, and is incremented whenever any change to any of the calibration commands is saved.

When performing the "stamping" test, the Trading Standards Officer will make a note of the TAC, and advise the user that any change to this code which occurs prior to the regular re-inspection by the Trading Standards Office, will result in legal prosecution of the user.

The user software is required as a condition of approval, to make the TAC available to the weight display indicator or console, on demand.