FAQ

Self Verification is the process which allows scale manufacturers to self verify their trade approved weighing equipment covered under the NAWI (non automatic weighing instruments) Directive. Companies certfied for SV must be able to demonstrate strict quality control in all aspects of their business. The SV process streamlines the installation and commissioning of weighing equipment. However installed legal for trade scales are always under the control of Trading Standards and officers can check scales at any time, should they wish to do so.

Big is not beautiful when it comes to weighbridge load cells. Compression load cells such as our CPR and CPD are compact, stainless steel, fully sealed and designed to ensure optimum load introduction and accuracy. Their self restoring assemblies ensure the weighbridge deck quickly returns to equilibrium. Their size facilitates installation and ensures the lowest possible deck profile.

By comparison, cumbersome weigh beams are heavy and require gargantuan mounting assemblies. Huge in service cantilever loads put excessive strains on the mounting hardware and surrounding structures. Replacing them is a two man job and they are often difficult to remove due to corrosion. Contrary to popular folklore, they are not more reliable than compression load cells. Failure rates of Bilanciai weighbridge load cells have been shown to be much lower than comparable weigh beams.

And for the saving the planet conscious user, weigh beams consume much more energy during their manufacture and transportation!

The two terms are regularly misquoted.  Accuracy is a complex and often misunderstood term; more often than not confused with readability and repeatability. Weighing system accuracy is a function of a number of criteria including design, operational and environmental factors. Accuracy (or perhaps it would be better defined as inaccuracy) is a measure of the level of confidence that the recorded weight for a particular weighing operation is correct within predetermined tolerances. It is therefore usually quoted in terms of a plus-minus weight figure (e.g. 35.75 kg ± .05 kg). It should be noted that the accuracy tolerance in the case of single range scales is quoted as fixed error tolerance relative to the overall scale capacity (e.g. 1500 kg ± 0.5 kg). Therefore the relative inaccuracy when using such a scale at lower weighing ranges is increased in percentage terms. (e.g. the error is still ± 0.5 kg when weighing 100 kg). Multi-range scales overcome this problem by having a stepped error tolerance across the overall capacity range.

By comparison, repeatability refers to the repeatable nature of weight readings when the same load is placed on a scale two or more times. Although it can be a good measure of performance, the actual weight reading may still be inaccurate unless it correlates with an applied load of known value.

Readability (often called resolution) refers to the displayed weight reading on a scale which, for non weights and measures scales, may be different from the rated accuracy. In other words a 1000 kg scale may have a stated accuracy of ± 0.5 kg, but displays to ±0.1 kg.

.

There are a number of reasons affecting choice. Older type weighbridges were almost always pit design, to accomodate complex lever systems and allow adequate access to service these. Therefore it is often practical and cost effective to use existing pit civil works for upgrades. Note: Weightron specialise in replacing aging pit weighbridges. Special load cell supports and bespoke deck sizes acn readily be installed in existing pits based around the versatility of the Eurodeck's modular construction. Pit weighbridges do not restrict traffic flow on site and are therefore ideal where space is limited.

Pit weighbrdiges can be used as static and dynamic scales provided suitable approach surfaces are provided. Weightron offer a special dynamic axle weighing solution (Thruweigh) using CPD digital load cells.

 It must be remembered that weighbridge pits need adequate, regularly maintained drainage systems (and adequate ventilation if used in hazardous areas.) It goes without saying that accurate weighing requires vehicles to be situated completely on the weighbridge when weighing takes place (eg all wheels on the deck)

Surface weighbridges are typically lower cost to install and if required, can be relocated in a more cost effective way, especially if steel ramps are used. Surface weighbridges are more suited to areas prone to flooding. Safety requirements usually mandate the use of side rails.

Weightron have developed proprietary techniques to install weights and measures approved weighbridges on sloping terrain. Our sloping bridge technology uses special load cell mounting assemblies in conjunction with the weighbridge design to ensure correct load introduction and a stable structure, even under vehicle braking conditions. Weighbridges can be installed to accommodate slopes up to 1 in 20 either from end to end, side to side across the width of the bridge, or a combination of both.

Special anti-slip paint applied to the weighbridge deck prevents vehicles slipping down the bridge in wet or icy conditions.

This can be very confusing and the situation is not helped by terminolgy used!

Mass is a measure of the amount of material in an object, weight is the gravitational force acting on a body (although for trading purposes it is taken to mean the same as mass). Most modern weighing equipment measures weight not mass. 

Mass
Mass is a measure of the amount of material in an object, being directly related to the number and type of atoms present in the object. Mass does not change with a body's position, movement or alteration of its shape unless material is added or removed. The unit of mass in the SI system is the kilogram (abbreviation kg) which is defined to be equal to the mass of the international prototype of the kilogram held at the Bureau International des Poids et Mesures (BIPM) near Paris. Mass can also be defined as the inertial resistance to acceleration.

Weight
In general weighing parlance, weight is taken to mean the same as mass, and is measured in kilograms. Scientifically, however, it is normal to state that the weight of a body is the gravitational force acting on it and hence it should be measured in newtons (abbreviation N), and that this force depends on the local acceleration due to gravity. To add to the confusion, a weight (or weightpiece) is a calibrated mass normally made from a dense metal!

So technically should we really talk about 'massing' ourselves instead of weighing ourselves? Unfortunatley there is no verb 'to mass'.

Therefore, unfortunately, weight has three meanings and care should always be taken to appreciate which one is meant in a particular context.

Weighing on the moon.

It is well known that the gravitational pull on the moon's surface is significantly lower than on earth which is why astronauts appear to be lighter. If in deed a scale calibrated on earth was taken to the moon, astronauts would weigh less. (Unless some type of mass comparator such as an even arm balance were used.)  However, if that same scale were to be calibrated on the moon using calibrated masses, (remember mass does not change) then astronauts would appear to weigh the same as they do on earth (ignoring any buoyancy effects).

Have some fun by seeing what you would weigh on different planets by clicking here at the exploritorium