Weighing in on Weighbridges - Things You Should Know

Posted 29th May, 2018

Weighbridges are used in many industries. They are the chosen piece of equipment for monitoring the weights of all manners of materials bought and sold throughout the world. The scrap metal industry is one of the industries that use weighbridges. Due to scrap metal being sold by weight, (kg or tonne) if you go to a scrap yard you are highly likely to come across one. With this in mind, we wanted to talk to some experts in the field of weighbridge installation and servicing. We aimed to find out how you can be sure that when your vehicle filled with valuable scrap metal is being weighed, you will have an understanding of how they work, how accurate they are, what can go wrong with them and what you, the customer should expect from the owner of the weighbridge.

We enlisted the help of Weighbridge Services, a Yorkshire based company with over 30 years’ experience in selling, installing and servicing weighbridges and other industrial-scale weighing equipment. If anyone could help you and us to have a better understanding of weighbridges, it would be them.

Weighbridges are a considerable investment for any scrap metal company, whether large or small. They can start at £8000 for a used/refurbished one. If you are looking for a new weighbridge, a 16m x 3m, with ramps, installation, and testing will start at around £20,000. This is a starting figure and could easily exceed this depending on the individual requirements of the scrap yard.

People delivering scrap metal to scrap yards will use weighbridges without knowing how they work. We asked Liam Buxton of Weighbridge Services to explain how weighbridges function, what can go wrong with them, how often they should be calibrated and a bunch of other questions.

How do weighbridges work?

“A weighbridge works by having a large steel platform (the weighbridge deck) resting on, normally, six load cells (these are the parts that weigh the load). The load cells create a digital number (called points) which it sends to the weight display. A ‘resting’, empty weighbridge has a certain number of points which is converted by the weight display to a ‘0’ (zero) weight on the screen. When the weighbridge is loaded with weight, the load cells send out a higher number of points which weight display converts into a weight on the screen.”

How accurate are weighbridges?

“A standard weighbridge setup weighs in 20kg increments, but we can create bespoke systems that can weigh some ranges from 5-10kg upwards. Trading standards (if buying and selling) have a set range we are required to use for calibrations so as long as you are within that range, you can buy and sell from your weighbridge legally.”

How often should weighbridges be calibrated and serviced?

“There is a general rule of thumb that the Weighbridge should be checked/serviced every six months with an annual calibration, using certified test weights every 12 months. We provide Service Contracts to customers to cover this type of work, including the test weight hire to aid in keeping things 100% correct and working accurately. Although the 12 months calibration is not a legal requirement, most ISO auditors require a certificate every 12 months to allow accreditation to their standards.”

What parts are likely to be repaired or replaced during a service?

“The load cells within the weighbridge need cleaning and greasing to keep them protected from the elements. The weighbridge is tested to make sure the weights are correct, and if not, it is re-calibrated. The weight display and printer are checked for correct operation. There is a central junction box which is also checked and tested to make sure the weight is being sent and received by the weight display correctly.”

Should scrap yards display the calibration certificate or servicing information?

“Yes, the certification is required to be kept with the weighbridge weight display with the date of the last calibration displayed. When using the systems for trade (buying and selling), there should also be a legal trade sticker applied to the weight display and any connected displays. This proves that the weighbridge has been tested to the correct standards. This sticker will also state the maximum and minimum weights that can be applied and the accuracy.”

What could members of the public look out for with regards to checking that the weighbridge is well looked after?

“In addition to seeing that the legal trade sticker is applied, when using the Weighbridge make sure they can see the weight display and that it is resting on ‘0’ (zero) before entering the weighbridge. If there is a weight on display (even creeping ups and down) it means, there is an issue and the weights taken could end up being incorrect.”

Are people within their right to ask for the weighbridge to be tested before driving on it?

“In short, yes. If the weight displayed is thought to be inaccurate, there could be losses of value to either party making it beneficial for the scrap merchant to have the weighbridge tested, outside of the annual tests. Although legally this cannot be forced upon a company, a scrap dealer may test a weighbridge in front of you if they wish. If there are any concerns or complaints, the weighbridge Trading Standards can be called who will deal with the issue directly.”

A big thank you to Liam Buxton of Weighbridge Services for answering our questions and helping us to have a better understanding of how weighbridges work. The people who use weighbridges must have confidence that the owner or operator is maintaining their equipment properly. Maintenance and servicing of such equipment need to be transparent. By people requesting to see maintenance and servicing records, it will inevitably help to discourage unscrupulous trading and to improve the scrap metal industry for everyone.

If you believe someone has broken trading regulations you can make a complaint to Trading Standards via their website HERE .

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