C.6
USE IN “APPROVED” APPLICATIONS (only as information)
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 78.1 (e.g.) has been approved as a component for use in weighing systems according to OIML
recommendation R76, the highest performance level approved being Class III, 5000 division. The approval
Authority was the Danish Electronics, Light & Acoustics (DELTA), and the approval certificate number was
DK0199-R76-02.02 Revision 1, dated 30.07.2003. 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 digitizer, 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
0.7
m
V 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 DAS 72.1 digitizer 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.
Manual DAS 72.1
Page 55
