If your belt weigher, weightometer, or conveyor belt scale is showing a flow rate while the belt is empty, the cause may be mechanical interference, a speed signal problem, a load-sensing fault, wiring, electronics, or calibration.
This guide covers safe first checks that can help describe the problem.
- Confirm that the belt and upstream feed are genuinely empty.
- Record the displayed rate, belt speed, fault messages, and recent work.
- Look for visible build-up, spillage, obstructions, or anything contacting the weighing equipment.
- Treat speed, load cell, wiring, and integrator faults as technician work.
- If the reading persists or you are unsure what you are seeing, contact Accurate Industries for advice and assessment.
Why can an empty belt show a flow rate?
A belt weigher uses load-sensing components to measure the material carried on the belt. If an external force affects the weighing system, the equipment may interpret that force as material.
Possible causes include:
- build-up, carryback, or spillage around the weigh frame or idlers;
- a rock or other material lodged against the weighing equipment;
- a roller, frame, or belt problem;
- a cable, hose, or conduit contacting the weighing equipment;
- a speed sensor that is damaged, misaligned, intermittent, has worn bearings, or incorrectly configured;
- load cell, junction box, or cabling faults;
- an integrator or configuration problem; or
- a zero, span, or calibration issue.
The cause usually cannot be confirmed from the displayed rate alone.
Safety before any physical inspection
Work on or near a conveyor, or inside an electrical enclosure, needs isolation under your site’s procedures and trained, authorised people. If that’s not you, stop and call us on 1300 101 666.
Five safe first checks
1. Confirm that the belt is empty
Check that upstream equipment has stopped feeding and that material has cleared the conveyor. A belt may look empty at the weighing area while material is still moving through the system.
Once the belt is confirmed empty, note whether the displayed rate changes as the remaining material clears.
2. Record what the integrator is showing
Before changing anything, record or photograph:
- the displayed flow rate;
- the belt speed reading;
- any error codes or fault messages;
- the total shown, if relevant; and
- the time and operating conditions.
Also note whether the rate is steady, drifting, jumping, or changing with belt speed.
Do not reset settings or change calibration values just to make the display return to zero. That may remove useful diagnostic information or hide the underlying problem.
3. Consider recent work or changes
Think about what happened before the problem appeared. Relevant changes may include:
- recent installation or commissioning;
- belt replacement, belt splicing, or retensioning;
- roller, idler, load cell, or sensor work;
- conveyor relocation;
- cleaning or washdown;
- electrical work or power interruption; or
- changes to the integrator, PLC, SCADA, or communications.
Record the timing of the change. This information can help a technician narrow the diagnosis.
4. Look for visible interference
From a safe position, look for visible signs of:
- material build-up or carryback;
- spillage around the weighing area;
- rocks, tools, rags, cable ties, or other objects contacting the equipment;
- damaged or displaced guarding;
- a cable, hose, or conduit pulled tight or visibly resting where it should not; and
- damage, movement, or unusual positioning of the weighing structure.
Do not reach into the structure or attempt to remove anything unless the conveyor has been isolated and you are authorised to carry out the work.
5. Decide whether the problem needs a technician
Contact Accurate Industries if:
- the rate does not return to zero after the belt is confirmed empty and visible interference has been addressed safely;
- the belt speed is zero, unstable, or inconsistent with the actual belt movement;
- an error code or fault message is displayed;
- the weighing equipment, frame, idlers, rollers, or structure looks damaged or out of position;
- wiring, load cells, junction boxes, sensors, or electrical equipment may be involved;
- the problem started after belt, roller, installation, or electrical work; or
- you are not sure what you are looking at.
What should a technician inspect?
If the problem persists, a technician may inspect the complete weighing system and surrounding conveyor, including:
- the weigh frame and mounting points;
- load-sensing components and connections;
- weigh, approach, and retreat idlers;
- rollers, shafts, and frames;
- belt tracking, belt condition, and belt tension;
- the speed sensor, its bearings, and its mounting, where fitted;
- cabling, junction boxes, terminations, and earthing;
- the integrator, display, communications, and relevant settings;
- material build-up, carryback, spillage, and obstructions; and
- the surrounding structure, vibration, access, and guarding.
The inspection helps separate a mechanical or housekeeping issue from a speed signal, load-sensing, wiring, electronics, configuration, or calibration issue.
What happens after the fault is identified?
The appropriate action depends on the cause. It may include cleaning, alignment, component adjustment, repair, replacement parts, electrical diagnosis, sensor work, recalibration, or a more detailed site assessment.
Accurate Industries can explain whether the issue can be resolved during the visit or whether it requires additional parts, lifting equipment, shutdown access, structural work, or a separate repair or commissioning visit.
Calibration should not be used to conceal a mechanical or electrical fault. If a problem affects the reliability of the measurement, it should be recorded and addressed as part of the recommended solution.
Does cleaning mean the belt weigher does not need calibration?
Not necessarily. If visible interference is safely removed and the empty-belt reading improves, that may explain the symptom. However, the equipment may still need a zero check or further assessment, depending on what caused the interference and whether the weighing system was disturbed.
Accurate Industries can confirm whether calibration, verification, or additional testing is appropriate for the equipment and application.
How does this relate to belt weigher calibration?
An empty-belt reading is one of the conditions considered during belt weigher service and calibration. What happens during a belt weigher calibration visit explains the process in full.
Accurate Industries can inspect the equipment, identify possible causes, complete appropriate service work, and carry out calibration checks where required.
Reports can record the as-found condition, findings, work completed, readings, recommendations, and as-left results. For customers using the service, AIMM, the Accurate Industries Maintenance Manager can retain equipment history, service reports, calibration information, and upcoming requirements against the relevant asset.
Frequently asked questions
Is it normal for a belt weigher to show a small rate on an empty belt?
A small variation near zero may occur depending on the equipment and operating conditions. A clear, steady, or increasing rate on a genuinely empty belt needs investigation, particularly if it is affecting the reported flow rate.
Do I need to recalibrate after cleaning the weighing area?
It depends on what caused the reading and what work was completed. Cleaning may remove an external interference issue, but a zero check or further calibration may still be appropriate. Follow your site procedure and ask a qualified technician when unsure.
Can I inspect the speed sensor myself?
Only if you are trained and authorised to access the conveyor and the work can be completed under the site’s isolation and safety procedures. Sensor arrangements vary, so do not assume that every belt weigher uses the same type of sensor or inspection method.
Does this guide apply to weigh feeders and tramp metal detectors?
This guide is about belt weighers, weightometers, and conveyor belt scales. Other equipment can have different designs, controls, and fault conditions. Contact Accurate Industries and describe the equipment and symptom before attempting physical checks.
What information should I provide when calling for help?
Have the following information ready where available:
- site and equipment location;
- belt weigher make, model, and asset number;
- displayed rate and belt speed;
- error codes or fault messages;
- recent belt, roller, installation, or electrical work;
- what you have safely observed or checked; and
- photographs of the display or visible condition, where permitted by your site.
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.