Can CST design and produce a 0.1% Belt Weigher?

Many industries have a need for the highly accurate weighing of bulk materials to a 0.1% standard. When very high tonnages as high as 5,000 to 10,000 tonnes per hour of valuable bulk materials are involved, conventional static methods of weighing become impractical. Truck weigh bridges and even automatic bin scales are some of the available static weighing technologies available however, these are high cost, high maintenance methods. There is a real need for a reliable 0.1% in motion belt weighing system. CST has a strong focus on and commitment to precision belt weighing and is capable of providing 0.1% belt weighing equipment to meet this challenge.

CST, together with our Canadian Agent, TD Micronic of Surrey, British Columbia have supplied a 0.1% belt weighing system to Vancouver Wharves and this equipment is now approved by Measurement Canada as a 0.1% weighing system. The approval number is AM-5612.

Vanncouver Wharves is a British Columbia Rail (BCR) owned facility which exports copper and copper-gold concentrate via ship among other products and they needed a 0.1% belt weighing system to monitor the export of this valuable material. The belt weigher was required to replace an aging automatic bin scale system. Under Canadian law, only ‘cheap materials’ can be legally weighed over a 0.5% weighing system, expensive materials must be weighed over a 0.1% certified system. Since the Copper-Gold concentrate has a value in the order of $1000 or more per tonne it is deemed an expensive material and hence the need for a 0.1% system. Of course the need for a 0.1% system could be justified for any large transaction since 0.1% is still $1,000 per $1,000,000. Even for low cost materials, a million dollars worth of dirt still costs one million dollars!

The equipment is installed on a 1050mm wide belt sloped at 8 degrees from the horizontal running at 2.8m/s and carrying a maximum of 1200 tph of copper-gold concentrate. Under Canadian Weights and measures law, the equipment had to be tested with three by 200 tonne test loads at a flow rate between 70% and 100% of full scale and the maximum allowable error had to be less than 0.07%, or in practical terms, less than 140kg and at the densties involved this is less than 100 litres of material. The most difficult problem in the testing was the management of the material. When, finally, all the material which had been pre-weighed was accounted for, the equipment easily passed the tests even though it had not ben adjusted for over 12 months.


The requirements of weights and measures authorities around the world vary quite a lot. In Australia we closely follow the European Union which produce documents through the OIML (Organisation International Metrology Legale) based in France. The OIML has produced recommendations R50 and R51 which are the basis of belt weighing in Europe and also by adoption, in Australia. In the USA, the NIST (National Institute of Standards and Technology) produce Handbook 44 which has grown up independently but which is becoming more and more influenced by OIML R50, they also approved wei. The USA has also approved in motion weighing instruments for trade use via their National Type Evaluation System (NTEP). In Canada, the regulations have also been developed independently however they are more similar to the US NTEP system than to OIML.

The interesting difference between the OIML and the other standards is that OIML requires test loads over a range of flow rates while MC and NTEP only require testing at full scale. As a result, the MC test which requires three test loads at or near full scale flow at 0.1% accuracy and the NTEP 0.25% test which also requires three test loads at or near 100% flow are not as rigorous as the OIML 0.25% tests which require that the accuracy be met at 100%, 50% and 20% of full scale flow. The 0.25% test at 20% of full scale is the same as requiring 0.05% of full scale accuracy from the system. CST have many belt weighers trade certified to 0.25% (OIML Class 0.5) in Australia.

CST along with our Canadian agent, TD Micronic are committed to the design and manufacture of 0.1% belt scale systems. We are prepared to supply OIML Class 0.2% systems in fact which will meet the 0.1% accuracy requirement right down to 20% of full scale flow rate. CST are working toward the acceptance of Class 0.2 belt scale system by OIML and we are already confident that we can design and build such systems. We achieve reliable 0.1% systems by designing each of the elements, the weigh frame, the idler sets, the loadcells systems, the electronics systems and the tachometer systems to high precision standards. In addition to this we, together with our Canadian Agents, TD Micronic, have developed some unique systems to keep the equipment running at the required level of precision. For example, our tachometer system is not only available as a dual redundant system but can be made self-checking so that it will adjust its meters per pulse calibration to take out the effects of tachometer pulley wear or buildup. Together with TD Micronic, CST are committed to producing the most accurate belt weighers in the world.

How accurate can my Belt Scale be?

Accuracy in belting weighing is one of the most commonly misunderstood areas and can be likened to fuel economy statements from vehicle manufactures. Fuel economy tests for vehicles tend to be either simulations or tests in closed circuit environments that are generally overoptimistic in the real world. It is the same for, and is often very misleading, when belt scale manufactures quote accuracy for their products, with the implication that this accuracy can be universally achieved,whatever the site conditions.

More than 25 years experience in the in motion weighing industry has convinced us this is not true. For example, if we take a consistently .25% accurate belt weigher from an environment (actual site or test lab) and install this on a new site it will be "lucky" if the belt scale was able to repeat the same results from the previous environment. The reality is that every site is different and there are many factors that will change from site to site, such as forces from the conveyor, temperatures, gravity etc.

At CST we firmly believe that every scale solution needs to be engineered and custom made to suite the requirements of each application. Once the engineering is completed we will be able to produce a belt weigher with a guaranteed accuracy.

If you want solid information to give you assurance that your belt weigher can meet your accuracy requirements, there are some important questions you need to ask:

  • If you are wanting to purchase a belt weigher - Ask the manufacturer to provide the engineering proof for your belt scale solution. If you need help CST can undertake an engineering assessment of your application. We will need you to provide information such as complete our inquiry form and provide a General Arrangement drawing of the conveyor and photographs where possible. We can guide you through this process.
  • If you already have a belt scale installed - Ask the manufacturer to prove their accuracy claim by running real world tests by using a controlled testing instrument such as a weighbridge.
How accurate can my Belt Weigher be?

Accuracy in belting weighing is one of the most commonly misunderstood areas and can be likened to fuel economy statements from vehicle manufactures. Fuel economy tests for vehicles tend to be either simulations or tests in closed circuit environments that are generally overoptimistic in the real world. It is the same for, and is often very misleading, when belt scale manufactures quote accuracy for their products, with the implication that this accuracy can be universally achieved,whatever the site conditions.

More than 25 years experience in the in motion weighing industry has convinced us this is not true. For example, if we take a consistently .25% accurate belt weigher from an environment (actual site or test lab) and install this on a new site it will be "lucky" if the belt scale was able to repeat the same results from the previous environment. The reality is that every site is different and there are many factors that will change from site to site, such as forces from the conveyor, temperatures, gravity etc.

At CST we firmly believe that every scale solution needs to be engineered and custom made to suite the requirements of each application. Once the engineering is completed we will be able to produce a belt weigher with a guaranteed accuracy.

If you want solid information to give you assurance that your belt weigher can meet your accuracy requirements, there are some important questions you need to ask:

  • If you are wanting to purchase a belt weigher - Ask the manufacturer to provide the engineering proof for your belt scale solution. If you need help CST can undertake an engineering assessment of your application. We will need you to provide information such as complete our inquiry form and provide a General Arrangement drawing of the conveyor and photographs where possible. We can guide you through this process.
  • If you already have a belt scale installed - Ask the manufacturer to prove their accuracy claim by running real world tests by using a controlled testing instrument such as a weighbridge.
How accurate is my Belt Weigher, really?

CST can analyse your installation, taking into account conveyor layout, belt tensions, weigh frame type, tachometer and calibration systems to give you an assessment of the likely range of systematic and random errors which you are likely to encounter.

How can I get on site support for my Belt Weigher, regardless of brand?
  • We have the biggest service team. Globally, CST is the largest niche belt weighing solution provider.
  • Over the last 25+ years of operations we have attracted and trained highly competent staff and built significant expertise in maintaining both our own and competitor's equipment.
  • We have offices in three Australian states, as well as international agents, and are available nationally and internationally to service, install, commission, troubleshoot and provide consultancy engineering advice for all your weighing needs and problems.
  • Given the lack of support generally available in the field by other weigher manufacturers, it is quite common for us to commission/install and support our competitors' products.

Should you need some help with your weighing needs contact your nearest CST office or one of our international agents. We will be happy to work out what equipment you have and how we can best help you support it.

How can I know that my Belt Weigher is in good condition?

CST can provide a service to check the condition of your existing belt weigher to make sure that all of the elements of the system, the idler rolls, alignment, weigh frame, loadcells, cabling, junction boxes, tachometer, electronics (integrator) and PLC connection are in good working order and can provide an independent check of system calibration.

How can I prepare a budget for a Belt Weigher replacement?

CST can provide pricing for equipment, depending upon accuracy requirement, and provide installation estimates as well as estimates for commissioning and calibration. If information is available please complete our inquiry form and provide also, via e-mail, a General Arrangement drawing of the conveyor and photographs.

I have a Belt Weigher which has not been in service for some years, how can I have it re-commissioned?

The fact that a belt weigher has not been in service for a while does not mean that it is not still a good quality unit which can give good service in the future. CST's rugged weigh frames have an indefinite life and are an integral part of our quality weighing system. Weigh frames can be upgraded with new idler rolls, loadcells, tachometer systems and electronics if necessary.

It is possible to upgrade other makes of weighers as well, depending on their condition and performance history..

Contact your nearest CST service office to start the process.

I have a breakdown, What options are open to me?

Your best option is to contact your nearest CST office. Before doing this, take the time to have information available that will assist the person trying to solve your problem. CST will be trying to isolate the source of the problem so information such as alarm signals, whether or not the weigher is seeing speed pulses, any snippet of information about site conditions etc. will accelerate the time required to get the weigher going again.

Often this will require having a site electrician or process technician examining the weigher for basic diagnostics. Incidence of recent welding or lightning strikes etc. are helpful if a load cell fails. Also important is milliVolt readings from the load cell output.

I have a persistent performance problem, what are my options?

CST take persistent performance problems very seriously and will give your problem the highest priority and attention required to give you the support you need, and solve your problem.

Performance problems with CST equipment are documented and addressed as part of our ISO 9001:2000 quality system. We call these problems 'Opportunities for Improvement' (OFI) and the investigation is closely monitored, with our whole service and engineering team available to contribute to the solution.

This investigative process can also be applied to weighers made by other manufacturers.

Problems that are difficult to trace are often caused by a complex interaction of various site factors. In some cases CST may offer to undertake a special project with the site to fully investigate the problem and come up with a satisfactory solution.

I want to increase the competence of my Belt Weigher team, what options are open to me?

CST offer a range of training options which can prepare your staff for routine belt weigher maintenance:

  1. CST offers training schools on site including class room and practical work.
  2. CST offers training courses at strategic locations around Australia.
  3. If you are overseas, please advise your needs so we can plan training that suits your situation.

Please contact one of our Service Team for further information.

Should I purchase maintenance service with my order?
  • It is not compulsory but highly recommended. CST has more trained service technicians than any other belt scale manufacturer. We pride ourselves in our ability to get the best results.
  • You can determine what level of regular service you require, from a calibration check to a mechanical alignment with an accompanying CRF (Calibration Report Form).
  • With an increasingly mobile workforce, and intense competition for skilled, experienced workers, maintaining 'in house' knowledge and experience on site is becoming a real challenge. Our experienced, knowledgeable service team can solve that problem for you.
  • CST belt weighers are not just any old weigher. Our regular service and maintenance right from the start will ensure your site workers learn from our team, rather than learning bad habits, or applying common site practices like adjusting which other makes can require.
  • Maintenance Agreement customers are given first priority when there is an emergency call out.
  • We will work with you to determine the type and frequency of maintenance required, to minimise your costs and maximise your weigher's performance.
What delivery times can I expect when I place an order?

Delivery time varies with factory production, whether we need to supply rollers, and the time it takes to get information from the clients for design and then time taken for approval. Our stated delivery has been 8-12 weeks from order in our proposals for belt weighers.

Due to the complexity we double this estimate for Weighfeeders.

Lead time summary:

Custom design: 2 weeks

Belt Scale fabrication: 6-8 weeks following design approval

Weigh Quality Idler supply: 8 weeks following design approval

Weighfeeders: Lead time on application.

Delivery from our Sydney, Peakhurst factory is usually about 6-8 weeks following client approval of our design, dependent on factory load. This is dependent on design approval by the customer, for which we allow 2 weeks. However, because of customer circumstances, this has, on many occasions, taken from one to two months.

Our lead time for rolls can be up to 8 weeks from receipt of idler information.

What do I need to do to use a Belt Weigher for trade purposes?

The three essential components of a trade certification system are:

1. An approved belt weighing system. Most countries have a Weights and Measures authority which will certify belt weighers to certain accuracy standards.

2. A suitable reference scale or 'Control Instrument' to weigh the live test loads.

CST can provide a suitable Control Instrument in the form of a Portable Weighbridge which can be sent to your site. (LINK)The test circuit can be worked out on site and may require some modifications to conveyors or chutes.


3. A suitable test circuit to carry the material from the control instrument to the weigh frame or vice versa.

CST can advise whether the belt scale you have is of the trade certifiable type and can assist with modifying, overhauling or replacing your belt weigher to bring it up to standard.

What information does CST need to accept an order?

To place an order, CST requires a minimum of TPH, belt width, belt speed, idler spacing, belt width and expected or desirable accuracy. Details of idlers are needed also.

Beyond this, we would also like to know details of the application such as material, bulk density, length of conveyor, angle of inclination, screw of Gravity take-up, angle of wrap & postcode for delivery. Also of interest is where one proposes to locate the weigher on the conveyor and any special special requirements such stainless enclosures, NMI, special paint, specific speed sensor (e.g. spiral cage pulley), DIP etc.

It is best to know about these upfront and without them, we cannot offer an engineered and tailor-made solution.

What kind of Belt Weigher do I need for process control?

Typically a single idler belt weigher is selected for process control. However, at CST we recommend dual idler belt weighers as a minimum due to the increased accuracy and reliability for a very small incremental cost.

A dual idler scale will have a more stable calibration, will require less down time to maintain and will provide excellent process control information.

When there is insufficient space, by all means use a single idler unit, however, we usually recommend a dual idler system as a minimum. If economy is the most important factor, CST would still recommend a dual idler unit but suggest that Weigh Quality Idler Sets be left out. The result will still be superior to a single idler scale. Contact CST to discuss your needs and to obtain an engineering assessment.

What kind of Belt Weigher do I need for product reconciliation?

When product movements and asset valuation are concerned, there is no substitute for having the best possible accuracy. CST recommend as a minimum a four idler fully suspended weigh frame of the trade certifiable type for all material movement duties. Since belt weigher performance is very application sensitive let CST provide an engineering analysis of your application to advise the right weigh frame for 0.25% or better performance.

What makes a Belt Weigher System?

A belt scale system consists of 3 elements:

  • the weigh frame, which measures instantaneous mass,
  • a tacho which measures belt speed, and
  • the belt weigher electronics which integrates both these inputs to determine flow rate and totalised weight.

The belt weigher system thus integrates conveyor belt loading with conveyor belt travel to calculate the total amount of material that has been carried past the weighing system and which also calculates the flow rate of material (almost) instantaneously. So with a belt scale on your conveyor you can see how much material has travelled this day, or this shift and you can also monitor your plant output in tonnes per hour, or some other convenient unit.

What do we mean when we talk about 'conveyor belt loading' and 'conveyor belt travel'?

To measure 'conveyor belt loading' we insert a weight sensitive frame into the conveyor structure which supports a section of the loaded conveyor. This 'Weigh Frame' weighs a specific length of the loaded conveyor which we call the 'Weigh Length' whose length might be measured in metres and the weigh frame is also calibrated to read weight in real units such as kilograms. As a result, the weigh frame is able to take a measurement of the kilograms per metre belt loading that happens to be the case at this instant on the loaded conveyor.

When we speak about 'conveyor belt travel' we mean how many metres of belt are travelling by. To measure belt travel we use a wheel or pulley in contact with the belt which is called a 'tachometer'. The tachometer has an electro-mechanical system such as metal tags and a proximity sensor which gives a set number of pulses per meter of belt travel. As a result, in any one time or distance interval, we are able to measure both the distance the belt has travelled, probably calibrated in metres, and how much the material on that belt weighed, in kilograms per metre. When multiplied together, these inputs yield just the weight that has passed in the interval. The final steps are to sum this weight to a totaliser (counter) and to calculate a flow rate of the material, in some appropriate units such as tonnes per hour.

It is important to understand the difference between general instrumentation systems, which generally require only a low level of accuracy, say 3%, and belt weighing systems, which can require accuracies up to .1%. An instrument 'indicates' the flow rate of some material of interest, whether it be a liquid in a pipe or solid on a conmveyor. Other instruments indicate temperatures, densities, liquid levels, speeds and so on. Such indications are typically only about 3% accurate and this is usually enough to control a process or alarm something which must be monitored. Belt Weighing systems (Belt Scales) are, however, much more accurate and must be maintained with much more care than a general instrument to achieve the accuracies which are necessary, typically 0.25% or 0.5%. As such, belt scales claim to be 'weighing systems' not general instruments and they do require quite a different mind set in their maintenance and care to achieve their promised accuracies.

How can accurate measurements be made through the belt?

One of the most significant challenges in belt weighing is to make an accurate measurement of material on a conveyor belt, through the conveyor belt. The weigh frame is located in the conveyor and it supports a length of the belt, the 'weigh length', but how can accurate measurements be made through the belt? The weigh frame supports the belt via idler rollers or in some cases via a slider bed. The conveyor belt rests in contact with these rolls and belt tension tends to resist the slight movements downward which the weigh frame must make to record the weight. Thus it can be understood that belt tension as it interacts with weigh frame alignment can have a dramatic effect on weigh frame accuracy. The answer to counteracting the 'lifting' effect of belt tension is to build a weigh frame which is robust enough to not move sgnificantly under the influence of belt load and which is long enough to support enough material to reduce the influence of belt tension errors. When a weigh frame is designed adequately, taking in to account and compensating for a variety of factors which work against accurate weighing of the material passing over the weigh frame, the belt scale is a true weighing system, not merely an 'indicator'.

To allow a belt scale to read accurately it must be calibrated.

To achieve this, a weight and length reference is used to calibrate the weigh frame and a length reference is used to calibrate the tachometer. When the weigh frame is strong enough and of sufficient length (Designed for an Accuracy) it can be calibrated accurately with static mass directly applied to the weigh frame. This static mass is our reference mass which is traceable to a National Weight Standard. The weigh length is measured accurately with a certified tape. As long as the weigh frame is well -aligned, we know have a calibrated weighing system able to accurately measure the linear density of kilograms per metre on the conveyor. To calibrate the tachometer the best way is to measure the total belt length with a certified tape and to also capture the number of tachometer pulses in one complete revolution of the belt. In this way we have a highly accurate independent calibration for the tachometer.

The calibration of a belt scale can be established by independently calibrating the weigh frame and the tachometer or the complete system can be calibrated with a test load of real material often termed a 'live load'.

Live Load/'Closed Loop' Calibration vs Static Load/'Open Loop' Calibration

The use of a live load for calibration is an absolute test, which tests every aspect of the weighing system; this can be termed a 'closed loop' calibration.

A static weight calibration, however, is part of an 'open loop' calibration. What we mean by that is that when we install, align, commission and calibrate a belt weigher, we are making sure that all the individual parts of the calibration are good. We make sure that we do the 7 Essential steps for successful Static Load Calibration:

  1. The weigh frame is well designed for this application
  2. The weigh frame is located in the right location
  3. The weigh frame is installed straight and level and the idler sets are also square and level and aligned to tolerance
  4. The weigh length has been measured properly
  5. The weigh frame is calibrated correctly with a reference mass
  6. The tachometer is correctly calibrated
  7. The total system is tested and shown to be repeatable and demonstrated to produce the outputs we expect with the test loads we apply.

It is not possible to really know how well the total system works until we 'close the loop' by using live load testing. However, CST have had an excellent experience of 'open loop' calibration because we do notcompromise any one of the 7 steps outlined above. In some cases it may be necessary to perform a live load test to convince the customer that the system really is working well.

This dead weight vs live weight or Open Loop vs Closed Loop calibration question is what can make belt weighing a challenging technology and this is why CST is determined not to compromise any of the steps required to achieve a credible repeatable calibration.

Microprocessor-based Electronics

These days, most instruments and weighing system use microprocessor power to gather data, perform calculations and display and transmit the results. Belt weighers are no exception, and modern belt scales have benefited dramatically from the introduction of modern processor based technology. The role of the electronics set is to accept weigh frame and tachometer data, to provide a means of calibration, to multiply the inputs together, to calculate a flow rate and update a totaliser, or tonnes counter. The electronics set has sometimes been called an integrator, but this is only a part description. In fact, originally integrators were used with all types of flow meters (which produce a tonnes/hour or litres /second etc output) to integrate this flow rate against time to work out the total tonnes, total litres or whatever has passed. Some older analog belt weighers were initially produced as flow meter instruments (little better than an indicator) and they were combined with an integrator to produce a total, and so the name has stuck.

The role of the modern belt weigher electronics set has grown considerably since the early days of belt weighing. Now one of the most important roles of the electronics set is to make calibration and maintenace of the belt weighing systems easier and more accurate.

Zero Setting

One of the most interesting aspects of belt weighing is the way in which the Zero setting is achieved, and this is becoming so much easier with modern microprocessor based electronics systems. As can be appreciated, the weight of the weigh frame itself, the idler sets on the weigh frame and the conveyor belt resting on the idler sets on the weigh frame are not what what we are trying to measure. The zero setting is how we subtract off this ever present but irrelevant weight so that only the weight of actual travelling material is measured.

The problem is, however, that the weight of the conveyor belt itself is not constant, it varies surprisingly and considerably along its length and to have a proper accurate zero setting, it is necessary to take into account the weight of the belt along its entire length and to use the average weight of the belt in the zeroing process. As a result, a zero adjustment for a belt scale requires that the entire belt be circulated at least once so its average weight can be experienced. This can take a little time and makes belt scales more difficult to manage than static scale systems.

Modern electrronics systems make this process automatic, so it is often called 'auto zero' and they can also intitiate the process automatically when the flow rate is near zero and this is called 'zero tracking'. Now, with the increasing capacity of electronics sets it has become practical to actually remember a zero setting for each part of the belt and to zero off the pre-weighed belt weight for each weight calculation along the entire length of the belt. This use of a belt 'zero image' sometimes also called a 'footprint' is an exciting development which in many respects converts a belt scale into a static scale. This is really only possible in this era of computer technology, as you can imagine, rather than remembering just one 'zero constant' a belt scale needs to remember hundreds of zero constants, in fact in our system we have capacity to remember over 2500 zero constants.

So a modern belt weigher electronics is now much more than a simple calculator or integrator or display device, it has become a specialised computer dedicated to getting the most out of the information inputs and dedicated also to making the task of living with a belt scale as easy as possible. Now with the internet available for the connection of smart instruments such as belt scales it is possible to monitor these devices remotely, to gather data about cargo deliveries, process throughputs and material movements, to check for correct operation and to carry out some remote maintenance.

In summary then, what makes a belt scale a system? Although designed to make some relatively simple measurements and using such fundamentally simple input devices as a weigh frame and a tachometer system, a belt scale is a sophisticated microprocessor controllled measuring device which is constantly monitoring many inputs , in motion, in real time. If taken seriously a belt weigher system can produce reliable management data for sustained periods between maintenance and can provide output and analysis directly to a computer in front of the process operator or stakeholder, anywhere in the world.

What makes CST's Belt Weighers the best and most advanced Belt Weigher?

The level of knowledge incorporated in a product is what makes it stand apart from other products and the best or most advanced product in the market. Another way to say this is that the quality of a product is proportional to the extent of knowledge incorporated in it.

CST has a detailed and extensive knowledge of the factors that contribute to, or work against accurate weighing, in situ. Through the application of professional engineering knowledge, these problem factors can be eliminated or minimised. We do our very best to get as much detailed site information as possible from our customers, and prefer to be involved in helping determine where the weigher/weigh feeder is placed on the conveyor. In designing each and every weigher, our professional mechanical design engineers input site information into a complex spreadsheet based on mutliple engineering equations, in order to create a weigh frame that will give the desired accuracy ‘in the field’, under your site’s real world operating conditions.

We aim to have a close and ongoing relationship with our end user customers – we are not selling just a product, as much as a comprehensive service, from design, to installation, and ongoing service and maintenance. We stress this relationship, becasue we know that in this way our customer is getting what they want and need.

In terms of overall plant investment, the cost of weighing equipment is quite low, whatever the quality. However, our extensive experience troubleshooting mysterious problems that have led to a plant shutdown, reinforce very strongly our belief that upfront application of engineering design, to suit each and every weighing application, is the way to go to ensure bankable accuracy, ongoing reliability, low maintenance, and avoidance of shutdowns.

Our equipment though very reliable, is not ‘set and forget’. We make it our business to ensure that our equipment is installed under our supervision and maintained with regular site attendance. This is how CST is aware of the practical needs and problems of the customer and this knowledge combined with our ongoing investment in research and development of our products and our technology at the forefront of the industry.

Knowledge alone, however, is not enough. Accurate weighing requires a philosophy based on strong ethical principles. How can we succeed in a business which is about providing true data without ourselves being committed to truth telling. How can we succeed in a business which is about providing trustworthy and reliable equipment without ourselves also being reliable and trustworthy. The company expresses its character in its products and services. It is only necessary to add to in depth knowledge and solid ethics sufficient hard work and industry to produce excellent products and services. CST has a strong ethic of working hard to reward the trust of our customers with a good product and an overall good experience. We are not infallible, but we are strongly motivated by problems to maintain the relationship of trust with our customers, and at the same time, extend our knowledge through the solutions we find, and hence improve our products.

At a more concrete level, what is the essence of CST’s claim to be the manufacturer of the best and most advanced belt weighing systems? One significant factor is CST’s background in electronic and mechanical engineering. From this professional knowledge base, we have been able to translate the customers performance need into a product which is very strong both electronically and mechanically. CST’s electronics used the full power of the microprocessor when it was first developed in 1984. It was not a microprocessor emulating a solid state design as so many of the competitive instruments were. The original electronics hardware and software design, with only minor changes became our trade certified belt weigher indicator. This meant that effectively, all of the electronics sets we were supplying were designed and were operating to the highest (OIML R50) metrological standards right from the beginning. Further more, our original product had the ability to be completely remotely controlled (via modem before the internet) and incorporated many advanced testing and calibration features which are unique in the industry, even 25 years later.

From a mechanical standpoint, our mechanical engineering knowledge combined with our uncompromising quality approach means that our weigh frames are the strongest and most stable units in the market place. Our earliest customers which we won back at those times have enjoyed our new standard of belt weigher reliability and have stayed with us year after year repeat purchasing our equipment for each new expansion, and installing our product enhancements and improvements along the way as well. As a result of our serious mechanical approach, our weigh frames were trade certifiable (OIML R50) right from the start, we only provided the best equipment, what better method could there be to build a sustainable business and relationships of trust with our customers.

The best and most advanced product is however of no use to the customer unless that is what they need. This the basic secret of our success. We have not produced a product which we think people want and mass produced it, rather, we ask every customer, every time we receive an inquiry, what their precise needs are. As a result we ask many questions about each application and we specifically engineer a solution which fits the need, one which is truly fit for purpose. While CST do have standard designs we have no standard products and we have no standard price list, every application is individually engineered, individually sized and individually priced. We listen to the customers needs and use our knowledge, experience and professional skills to design the best and most advanced belt scale that exactly meets the need. That’s why CST Belt Scales are the Best and Most Advanced Belt Scales in the market.

What should I do to keep my Belt Weigher in good condition?

Keeping your weighing equipment in peak condition will ensure that you maintain the designed performance and achieve maximum life from your products.

Faults that are not identified early can have direct impact on weighing performance and lead to much larger consequences. For example, a damaged roller will skew weighing results, and could cause excessive belt wear causing a belt to be replaced sooner than required.

Simple things like, keeping the equipment clean and having trained service technicians working on our products is a good start.

It is recommended that a more formal quarterly and annual maintenance program is in place to ensure that the equipment is kept in good condition.

What Services and CST offer me?

CST offers annual and quarterly maintenance regimes which covers maintenance and replacement of wearing parts, the checking of electrical connections and calibration stability. As part of our standard maintenance CST maintains records which are an important feedback loop for customers to understand the performance of their equipment and can be used to monitor drift and other performance metrics over time.

I want my technicians to maintain our weighing equipment on-site:

CST is prepared to work with service teams on site to ensure that staff involved in the up keep of weighing equipment have the necessary skills/training to cover basis maintenance tasks.

When is it time to change my Belt Weighers?

At CST we design and manufacture with high levels of quality and we have a range of options to protect our products from the harsh environments, extreme temperatures, above ground, underground and corrosive environments. Apart from the consumable components, with the right protection and maintenance the mechanical components can last indefinitely in the field. We are proud to say that there are CST belt weighers installed in the field over 24 years ago that are still in service today.

That said, here are some of the circumstances where we would consider replacing the belt weighers:

  • Accuracy requirements have changed
  • The belt weigher is damaged beyond repair
  • Your existing system is not meeting your requirements

If you are not sure or need some help to determine if a belt weigher is serviceable, our sales and service teams will be able to help assess your equipment and advise whether replacement or refurbishment is the best course.

Where can I get spare parts for my Belt Weigher?

I don't have CST weighing equipment:

CST are able to source spares for most models of belt weigher equipment. If we don't have the actual parts you need we can easily adapt some of our standard parts to get your system going, by using our own tachometer system or electronics sets as replacements for faulty equipment.

I have CST weighing equipment:

Since inception CST have kept records of product manufacturing, shipping, customer and location details. If you have a CST product in the field no matter the age, it is very likely that we can locate detailed product information that can lead the to sourcing or manufacturing of replacement parts/components.

Please contact our Service or Sales team who will do their best to help you find what you are looking for.

Why are all CST's Belt Weighers custom designed and built?

All CST's belt weighers are custom designed and built so that they will meet the customers performance needs in their actual application.

There are some commonly held ideas about belt weighers in the industry, that, for example, a four idler belt scale is a 0.25% accurate device, regardless of the type of material, the belt tension, and a host of other site factors which have a significant effect on weigher accuracy. That this is plainly not true is reflected by the general poor opinion of belt weighing accuracy held by most in the bulk handling industry, who have been taken in by this kind of marketing.

It would be well accepted that most conveyors are different to each other, each has a different length, different lift, different capacity, belt speed, profile and so on. As a result each conveyor has a unique belt tension environment and presents often radically different environments in which a belt scale would be expected to operate.

Belt scales are extremely application specific, that is, it is not possible to consider the accuracy of a belt scale except in the context of the actual conveyor which it is to be built into and the actual duty which it is to experience in that conveyor. This is why CST use their engineering knowledge to design a specific belt scale for each application, so that the performance of the belt scale can be as required by the user rather than hoping that the theoretical accuracy offered by some standard 'off the shelf' equipment manufacturer will be able to replicated on site.

As previously mentioned, it is plainly not true that a four idler belt scale is a 0.25% device and a two idler belt scale is a 0.5% device. In fact, here at CST we promote a different wisdom, we say that you need 'Different Belt Weighers in each Different Conveyor to achieve the same accuracy.

An accuracy of 0.5% is commonly requested for a site which has many belt weighers such as a typical Coal Preparation Plant (CPP). In reality the customer would probably prefer 0.25% however the 0.5% choice is made as a practical cost compromise.

The plant will however have many different conveyors with a variety of lifts, lengths, widths, capacity and so on, each presenting a different belt weighing challenge. Would it not be ideal if every belt weigher on the site would work to the same level of confidence, in other words, if each belt weigher would always produce true results with an error no greater than 0.5% of the actual flow, down to 20% of capacity. CST's design process is not unlike the concept of the Reynolds Number which is used in pipe flow calculations (http://en.wikipedia.org/wiki/Reynolds_number. The reynolds number allows the designer to say 'these flows are alike' even though they are happening under very different conditions. Therefore using our design process, CST is able to design all of the belt scales on a site to achieve the desired accuracy, to the same level of confidence. Of course, in doing this, CST is designing a specific solution in each case and as a result, CST will design different belt scales for each different conveyor to achieve the same performance.

CST have automated the design for each of their products. The conveyor environment data is fed into the design program and the outputs are all the design characteristics of the belt scale and at the same time a pricing calculation is performed. Additionally, at the same time, the description of the product with pricing is produced, is transferred to the written proposal for the customer and becomes the basis of our offer. CST have been at the forefront of computer technology for some time and have been emailing pdf versions of our offers to customers rather than using paper offers for more than 10 years at this time. Due to our Computer Aided Design process, we are able to send fully detailed offers, detailing our custom solution for your specific conveyor in a very timely manner. We look forward to the possibility of providing this service for you. See our belt scale inquiry questionnaire.

Why is it important to have 100% calibration mass weight?

100% Calibration Mass is important because it represents the full span of your weigher. If you calibrate at say 30%, any errors will be doubled when the belt runs at 60% of full load and then trebled when belt runs at 90% of full load.

Why should CST do the installation and commissioning?

All Belt weigher companies have their own cultures. The culture is the sum of the beliefs, practices and accumulated knowledge acquired over time, which is not available outside the company. The culture in CST rests on two main things – applying scientific knowledge, and demanding a high standard of ethics. CST strongly promotes its proprietary knowledge and way of doing things within the company by training and by regular communication between their technical community.

The CST belt weigher is not just the product, it is also the company that comes with the product. CST installation and commissioning gives the customer the following advantages:

  • in depth knowledge of the equipment
  • understanding of the key installation criteria required to guarantee meeting accuracy requirements
    • For example, unless logistically impossible, CST always measures the complete conveyor belt to establish tachometer calibration, except in the case of very long conveyors. This is necessary because any error in the bel tmeasurement will translate directly into an accuracy error e.g. .1% error in belt length measurement will lead directly to a .1% error in accuracy. CST endeavout to measure at least 1 complete belt revolution OR at least 1000 pulses.
    • A real example of the WRONG way to do it: CST has found on site the following bad practice – One company was measuring off 50m of belt, timing it, and then timing the complete belt revolution to obtain the complete belt length. This process was plainly no more than about 0.5% accurate, and yet it was part of a regular belt weigher ‘service’ being paid for by the end user. This process was being carried out on belt weighers which were supposed to be 0.25% accurate.
    • There are many similar stories, such as this one, about the WRONG way to do linearity testing: another maintenance company was doing repeatability testing of our equipment on the basis of observed flow rate rather than the very precise, CST built-in ‘linearity testing’ routines. They were reporting our equipment as about 2% repeatable. When the customer took back this outsourced service and used correct CST procedures, they confirmed that, as per CST performance guarantee, our equipment was 0.1% repeatable. Service that is not done with adequate experience and knowledge, or correct technique, can cost the customer more than just the service fees, due to inaccurate weighing.
  • Strong motivation to ensure peak operation performance, based on confidence in the ability of our weighers to deliver on our performance guarantee.
  • Full backup support from the factory and technical support staff.
  • CST invests considerable time and effort into creating, maintaining the technical expertise ‘in house” to ensure our weighers perform as guaranteed. Maintaining our quality control in the installation and commissioning phase is as pivotal as in the manufacturing phase.
  • When it comes to installation and idler alignment, there is general agreement on the ‘how to’, although CST uses multiple lines to ensure idler placement is true and the weigh frame is square. However, a common problem that occurs when non-CST installation is done, is that mechanical tradespeople simple do not believe the tolerances to which we routinely work, and do not align according to our standards. An important part of our installation procedures is that we align idler sets to a tolerance of 0.3mm. This ensures the minimum negative effect from the twisting of the belt and resultant increased belt tension that misalignment of rollers causes. Unfortunately, it is our experience that unless CST does the work, there is no way to ensure that this standard is achieved.

It is important that the commissioning of the weigher is carried out to the same high standard. There is no substitute for having a CST specialist involved to supervise the work. Properly installed, and commissioned, CST weighers consistently perform true to the accuracy guarantee, requiring only routine maintenance, and consistently giving a performance life of 15 years and more.

Your insurance against sub-standard performance, and unnecessary breakdowns is in using CST expertise on CST weighers, or any make of weigher that you want to perform to optimum capacity.

Why should I order CST weigh quality idlers?
  • CST Weigh Quality Idlers are often specified as site standard because they are made of robust Square Hollow Section for superior rigidity.
  • Secondly, the cam adjustors are much easier to turn and take much less time to adjust for good mechanical alignment and hence, on-going accuracy.
  • CST proprietary Weigh Quality Idlers incorporate a swivel foot which relieves stress on the weigh frame thus allowing equal weight distribution to each load cell.
  • Our idler design also gives good clearance between the end of the frame and the stringers ensuring no jamming with process material.