Choosing a weighing machine
WHY BUY AN ARPEGE MASTER K scale?
Dear Customer,
With the Internet, the range of scales available has become not only difficult to interpret but very risky with regard to regulatory requirements.
By choosing products from our catalogue, you have the guarantee of a major manufacturer who has the necessary legal approvals and certifications, their own design department and production facilities in Europe and Asia enabling them to remain a leading player as regards performance and quality at a competitive price.
Our company and its network of independent retailers are among the most competent in the business and, besides giving you advice on your own particular situation, provide you the assurance of being in line with current legal requirements with equipment which can be repaired and checked on site on mainland France and the French overseas territories.
By choosing ARPEGE MASTER K, you have the best product available from stock in France at the best price/quality ratio for the uses you will put it to.
Thank you for your confidence
Georges Evesque, Chairman and chief executive
TERMINOLOGY AND PRACTICAL INFORMATION TO HELP YOU IN CHOOSING
BALANCE
The basic mechanism of a set of SCALES comes from the Latin "bis" meaning "twice" and "lanx" meaning "flat".
Modern definition: An instrument used to weigh and by extension any device used for weighing.
THE QUALITIES OF A scaleAs for all measuring instruments, there are three: 1) Reliability, 2) Sensitivity and 3) Accuracy or freedom from bias to which must be added a fourth, 4) Insensitivity to load off-centring.
The European standard governing the characteristics and performances required for scales intended for commercial transactions is EN 45 501.
CHOOSING A WEIGHING MACHINE
Question 1: IS IT FOR A USE GOVERNED BY REGULATIONS? (accuracy class)
Regulated use means that this instrument must be classified for Legal Metrology.
Legal metrology is governed in the European Community (CE) by national directives and regulations which are applied to manufacturers, retailers and users in the form of laws guaranteeing the quality of measuring instruments.
According to European directive UE 90/384/EEC, scales known as "non-automatic weighing instruments" fall under regulated usage for the following uses:
a) The determination of weight for commercial transactions,
b) The determination of weight for the manufacture of medicines and during analyses carried out in medical or pharmaceutical laboratories,
c) The determination of weight for the application of legislation or a regulation,
d) For the weighing of pre-packed goods.
Unregulated use, for this case, weighing manufacturers have invented the term "Not for legal metrology" for applications not included in the regulatory scope.
In this case, the equipment offered may be similar, but the metrological characteristics are not always guaranteed by a standard (EN 45 501), nor by regulations.
For "low cost" equipment, the electronics and load cells are of lesser quality, i.e. their indications vary with temperature and do not keep to the tolerances required by legal metrology.
Legal metrology lays down checks on the weighing instrument at three stages:
1) The design stage with the type examination,
2) The manufacturing stage with the "verification of compliance to type" (or primitive verification) for the instruments shown by the application of the CE mark,
3) The usage stage with the periodic inspection of instruments in service. Inspection is carried out in France by certification bodies approved by the State which affix a validity label to instruments in service.
Question 2: WHAT PRECISION DO I NEED? (accuracy class)
A scaleis characterized by:
Its weighing range, i.e. its maximum capacity: this is the maximum load which can be weighed and its minimum loading, most often 0 kg.
Its accuracy class (3 possibilities)
- Class II or fine precision (high-precision laboratory weighing),
- Class III or average precision (weighing used in commercial transactions),
- Class IIII or ordinary precision (domestic weighing or weighing not requiring great precision),
- Non-Legal metrology class, added by manufacturers and defining only what the manufacturer wants to guarantee.
Each class is defined by:
- Its number of scale divisions,
- The value of its division given by the letter "d".
The division is the difference between 2 consecutive indications for a digital indicator. In other words, it is the lowest value that the instrument is capable of displaying when the weight increases.
The number of divisions is calculated by dividing the maximum capacity of the instrument by its division value.
Let's take the case of an instrument with a maximum capacity of 30 kg and a division (d) of 10g: this instrument has 30000/10 = 3000 divisions.
- Its temperature range: for class II, the range is from +5 to +20°C. For classes III and IIII, the range is -10 to +40°C.
Question 3: WHAT WILL ITS ENVIRONMENT BE?
a) What is the normal ambient temperature?
In legal metrology the rule for standard ambient temperature is: -10°C to +40 °C.
b) How is it washed?
Soft damp cloth (IP40 to IP54) or high pressure washer (IP66 or IP67).
c) What is the moisture content?
The protection class given in the form IP XX (protection index) indicates this:
- IP 40 for equipment used in an office environment,
- IP54 for equipment used in a slightly dusty industrial environment,
- IP65 for equipment used in a damp environment with the risk of water spray,
- IP66 or IP67 for equipment used in the food industry.
d) Are there any food standards?
The quality of the stainless steel used for the plate is important. 316L stainless steel is required for food use if the product is in contact with the scale.
e) What is the power supply?
Is 240V mains supply available or do I have to use rechargeable batteries?
f) What is the ambient lighting: LED display (red diodes) visible in the dark, or LCD (liquid crystal) display requiring good ambient lighting.
Question 4: WHAT DO I DO WITH THE RESULTS OF THE WEIGHING OPERATION?
1) Print it:
The printout on self-sticking ticket or label may carry different information depending on the software and the keyboard of the associated electronic indicator.
2) Transfer it to a computer:
The electronic indicators in general have an RS232 serial link which allows weight data to be exported to a computer. In legal metrology, a "Data Storage Device" or "DSD" or "Alibi memory" is mandatory. This is a device to save regulatory data in order to keep in the memory of the indicator a legal trace of data sent by the indicator to the computer.
3) Use the piece counting function:
Using the average unit weight of a piece, it is possible to determine the number of pieces contained in a batch.