Test weights, calibration chains and material tests provide different evidence about a belt weigher’s performance. The right method depends on the installation, available reference equipment and what the site needs to establish. A useful calibration report identifies the method and conditions instead of treating every check as proof of accuracy in production.
Accurate Industries assesses the complete belt weigher, weightometer or conveyor belt scale before recommending the testing scope. For an overview of the work, see what happens during a calibration visit.
What does each calibration method check?
| Method | Reference used | What to keep in mind |
|---|---|---|
| Static test weights or built-in test weights | A known mass applied through the specified loading arrangement. | Checks response to that applied load. It does not reproduce every effect of conveyed material. |
| Roller calibration chain | A known linear loading applied over the required weighing length. | Loads the moving belt, but does not reproduce every material distribution or conveyor condition. |
| Material test | The same defined material quantity measured by the belt weigher and a suitable independent reference. | Checks totalised mass for the tested conditions. Reference quality, test boundaries and material handling matter. |
How do static test weights and billets work?
Test weights apply a known load at the frame’s specified test points. Some are fitted manually; others are stored on the installation and engaged through a built-in mechanism. “Billet” is a term used for certain test-weight arrangements, rather than a description of every calibration device.
The expected indication depends on how the weight acts on that particular scale. Check the manufacturer’s definitions of test load, effective weighing length, lever ratio and any inclination correction. Some frames use levers and others load the cells more directly; do not assume one formula or lever ratio applies to all designs.
Use the applicable reference value and loading arrangement. The mass stamped on a weight is useful identification, but its present condition and calibration record determine whether it remains suitable for the intended check. See care of test weights, chains and billets.
How does a roller calibration chain work?
A roller test chain is normally restrained over the weighing area while its rollers turn on the moving belt. It is not loose chain travelling around the conveyor. Its linear mass, coverage and installation must suit the system. The Siemens roller-chain manual illustrates this arrangement; use the instructions for the actual chain and scale.
The distributed test load can be useful where it suits the conveyor and required test range. It is not automatically a better choice than weights, and a satisfactory chain result does not establish performance with every product or belt-loading pattern.
Need a chain for a planned test? Accurate Industries offers calibration chain hire for belt weighers and weightometers. Send your conveyor details, site location and preferred dates so we can confirm suitability, availability and the hire arrangements. We can also quote a calibration visit if you need assistance with the work.
What makes a material test meaningful?
The comparison must account for the same material quantity on both instruments. Agree the collection or delivery arrangement, reference weighing, container or vehicle tare, test boundaries and treatment of any losses or retained material. Record the operating flow range and repeat the comparison as required by the test plan.
A reference instrument needs to be suitable for the mass and required confidence. A certificate or a large display alone does not establish that the particular comparison is adequate. Resolution, condition, uncertainty and handling can affect the conclusion.
A well-planned material test provides evidence about the complete system under the tested conditions. It is not an unlimited guarantee across all speeds, loads or future operating conditions. Manufacturer guidance also distinguishes routine test references from a material-based performance comparison: see Siemens guidance on belt-scale calibration and verification.
Is a static belt cut equivalent to a material test?
No. A static belt cut weighs material from a measured length of stopped belt to investigate belt loading. Sample selection, stopping effects and the relationship to the displayed reading limit the comparison. It does not test accumulated tonnes through a full running batch. See what a belt cut can and cannot establish.
When should each method be considered?
- Routine maintenance: use a suitable, repeatable reference method for the installation and compare results with its established service history.
- Commissioning or significant changes: agree how the required installed performance will be demonstrated, including a material comparison where needed.
- Unexplained totals or stock discrepancies: assess the comparison records and plan an independent material test if appropriate; do not assume the integrator needs a span change.
- Unstable mechanics or a poor weighing location: address those limitations. A material test can reveal their effect, but does not fix them.
- Between-service checks: follow the equipment’s approved checking procedure and record trends. A quick check should not imply more confidence than it provides.
Store-in-place weights or manual plates: what should a buyer consider?
Compare access, handling, calibration frequency, mechanism maintenance and the installed cost. Built-in weights can reduce repeated manual handling where the design and access suit the site, but their engagement and clearance still need inspection. Manually fitted weights need suitable lifting and positioning arrangements.
Neither option removes the need for a safe system of work. Discuss the planned test method while selecting the weigh frame and conveyor layout, rather than leaving calibration access until after installation.
What does an electronic or R-Cal check prove?
The answer depends on the design and where the test signal or shunt is applied. An internal simulator, shunt-calibration circuit and external test device may exercise different parts of the measurement path. Do not assume every electronic check tests the field cable, load cells or speed input.
It can be useful for checking the part of the circuit it actually covers, but it does not apply a real mechanical load. It cannot establish that the complete installation transfers material load correctly. Use the instrument manual to understand the check’s coverage and expected result.
What happens if the methods disagree?
Review the references and test conditions before changing settings. Check zero stability, speed measurement, load transfer, alignment and repeatability. A difference can come from the scale, the reference or the comparison itself.
Accurate Industries records the findings and explains the practical next step. Where a reliable repair is possible, we repair; where condition or performance justifies an upgrade, we explain that option. See repair versus upgrade.
Frequently asked questions
Are test weights enough on their own?
They may suit the agreed routine check, particularly when linked to an established performance baseline. Whether more testing is needed depends on what must be demonstrated and whether the installation has changed.
How often is a material test needed?
There is no universal interval. Consider the measurement’s importance, operating history, equipment changes and applicable requirements.
Are these tests legal-for-trade verification?
A maintenance check is not automatically trade verification. If the result is used for trade, establish the separate scope before booking. The National Measurement Institute provides the relevant Australian information.
Discuss the right calibration method or call 1300 101 666. Send the scale model, site conditions and the question you need the test to answer.
Need a manual for your equipment?
Talk to us about manuals for your equipment. Send the make, model, serial number and software version (a photo of the label is fine) and we’ll help you find the right document.