OWL EYE® Volume Flow
What is volume flow measurement on a conveyor belt?＋
Volume flow measurement is the continuous capture of the material stream on a moving conveyor belt — as volume per time (m³/h) instead of weighed mass. A 2D-LiDAR sensor above the belt scans the bulk material's cross-section profile line by line; from profile and belt speed the system computes the volume flow in real time, to ±1 % accuracy. Mass flow is derived via material-calibrated bulk density.
The difference from a belt scale: no moving parts, no wear, no recalibration after a belt change — plus belt load, height profile and mistracking detection that a scale never delivers. Multi-echo signal processing separates airborne dust from the material profile. Details: OWL EYE® VOLUME FLOW — conveyor volume flow measurement; the head-to-head comparison: LiDAR vs belt scale.
How do you measure the volume flow on a conveyor belt — belt scale, radiometric gauge, radar or LiDAR?＋
The material flow on a conveyor belt is measured either by mass or by volume. A belt scale weighs the material through idlers on load cells: 0.5–1 % mass accuracy when calibrated, with mechanical wear and periodic recalibration. A radiometric (nuclear) gauge infers belt load from the attenuation of a radioactive source: non-contact, but with licensing, shielding and source-disposal costs. Microwave or radar sensors give a point load signal without a cross-section profile. Volumetric LiDAR scans the material cross-section line by line and, with belt speed, computes the volume flow (m³/h) and — with density — the mass flow (t/h): ±1 %, non-contact, no wear, load profile included.
In practice the belt scale remains the reference for custody-transfer weight; for process control, retrofits without rebuilding the belt and multi-belt monitoring, OWL EYE® VOLUME FLOW is the non-contact conveyor volume flow measurement. All seven methods on the belt compared: conveyor belt volume flow measurement: 7 methods compared; for stockpiles and bunkers: six ways to measure bulk volume.
What is volumetric conveyor belt measurement?＋
Volumetric conveyor belt measurement is the contactless capture of the cross-section of material moving on a conveyor belt — converted in real time into volume flow (m³/h) and, with material density, into mass flow (t/h). Unlike a belt scale, which weighs the load through the belt frame, a volumetric system measures the actual geometric profile of the bulk material above the belt.
OWL EYE® VOLUME FLOW performs volumetric conveyor belt measurement with a single 2D-LiDAR sensor mounted 0.5 to 1.5 m above the belt. The sensor scans line by line, crosswise to the belt direction. Each scan becomes a profile cross-section; integrated over belt speed, it delivers continuous, wear-free volume and mass-flow data — accurate to ±1 %, available 24/7 via dashboard, REST API and OPC UA.
Typical use cases: replacing or supplementing belt scales on abrasive or wet materials, monitoring throughput on long conveyor lines, feeding live mass-flow data into SCADA / SAP / MES systems, and detecting off-centre loading or belt-edge spillage before it becomes a problem.
What is an optical belt scale — and how accurate is it compared with a mechanical belt scale?＋
An optical belt scale measures the material flow on a conveyor without contact: a laser or LiDAR sensor above the belt captures the cross-section of the belt load; cross-section and belt speed give the volume flow in m³/h, and the calibrated bulk density turns it into mass flow in t/h. It does not weigh — it computes from geometry — so there are no load cells, no wear and no intervention in the belt line during installation.
A mechanical (gravimetric) belt scale, by contrast, weighs with load cells under the belt: it is certifiable and remains the reference for custody transfer (below 0.25 %), but drifts by a typical 2–3 % between calibrations. OWL EYE® VOLUME FLOW is a LiDAR-based optical belt scale with ±1 % volume accuracy and no drift, which also delivers the load profile, off-centre loading and edge spillage. Head-to-head: belt scale vs. volumetric measurement.
How do you calculate mass flow in t/h from the measured conveyor volume flow?＋
Mass flow (t/h) = volume flow (m³/h) × bulk density (t/m³). The LiDAR cross-section multiplied by belt speed gives the volume flow; bulk density is the material-specific factor. Example: a belt carrying 250 m³/h of crushed limestone at 1.5 t/m³ moves 375 t/h.
With OWL EYE® VOLUME FLOW the bulk density is calibrated per material at commissioning — against a reference weighing (existing belt scale, weighbridge or sample weighing) — and stored as a material profile; moisture or grain-size changes get their own profile. The result is live volume and mass flow in m³/h and t/h at ±1 % volume accuracy, via dashboard, REST or OPC UA into your control system or ERP. The volume is always the primary measurement; the tonnage is only as good as the calibrated density. Basics: conveyor volume flow measurement; when the belt scale still stays: belt scale vs. volumetric measurement.
Which conveyor types and material flows are supported?＋
OWL EYE® VOLUME FLOW works on standard troughed and flat belts, regardless of band width or material — typical installations cover 600 mm to 2200 mm wide belts running at 0.5 to 6 m/s. Bulk densities from light wood chips (~200 kg/m³) to dense iron ore (~4000 kg/m³) are calibrated material-by-material on commissioning.
The 2D-LiDAR cross-scan does not touch the belt or the material, so abrasive, sticky, hot or wet bulk materials are no problem. Inclined and reversible belts are supported.
When is volumetric LiDAR the right choice over a traditional belt scale?＋
Choose volumetric LiDAR (OWL EYE® VOLUME FLOW) over a belt scale when one or more of these apply:
- Abrasive, sticky, hot or wet materials — a belt scale wears out fast or de-calibrates; a contactless LiDAR sensor mounted above the belt never touches the load and has no mechanical wear parts.
- Retrofit on an existing conveyor — installing a belt scale means working in the belt line: a weighing frame takes the place of existing idler stations, the belt has to stand still for it, and alignment and calibration with test weights follow. A LiDAR sensor goes on a small gantry above the belt in hours, no belt stop required after the brief mounting.
- You need profile data, not just total mass — LiDAR sees off-centre loading, belt-edge spillage, profile-height anomalies and can flag predictive-maintenance triggers. A belt scale reports only the integrated mass.
- Multiple belts at one site — one LiDAR per belt is significantly cheaper than rebuilding multiple belt frames, and all data flows into one OWL EYE® dashboard with one set of APIs.
- Material density varies — LiDAR measures geometry first; mass is derived per material calibration. A belt scale measures mass but cannot tell you the volume, which is what matters for stockpile-input reconciliation.
Stick with a belt scale when you have a single, well-calibrated, high-throughput belt with a uniform material and you need fiscal-grade weight accuracy (custody transfer at <0.25 %). For nearly every other industrial conveyor scenario, volumetric LiDAR is faster to install, cheaper to maintain, and gives you data the scale cannot.
Many of our customers run both: belt scale for periodic re-calibration of the LiDAR mass output, LiDAR for continuous monitoring and the extra geometric data the scale cannot provide.
Is there an alternative to a belt scale — and how accurate is belt weighing compared with LiDAR?＋
The alternative is the optical belt scale — volumetric conveyor measurement by LiDAR. A 2D-LiDAR sensor above the belt scans the material cross-section line by line; with belt speed this gives the volume flow (m³/h) and, via calibrated bulk density, the mass flow (t/h) — plus the load profile a scale never sees. No contact, no load cells, no wear, no intervention in the belt line.
On accuracy: belt weighing reaches 0.5–1 % of mass on a well-calibrated belt and 0.25 % on certified custody-transfer scales — but it drifts with material build-up, idler wear and belt tension and needs periodic recalibration. LiDAR measures ±1 % by volume after a one-off reference calibration and does not drift; its mass figure follows density stability (±1–2 % for homogeneous bulk, ±3–5 % for variable mixes). For fiscal invoicing the belt scale remains the reference; for process control, retrofits and multi-belt sites OWL EYE® VOLUME FLOW is the alternative — full comparison: belt scale alternative.
What accuracy can OWL EYE® VOLUME FLOW achieve?＋
Volume accuracy is typically ±1% on a calibrated belt. Mass output (tonnes per hour) follows from volume × material density, so mass accuracy depends on how stable the bulk density is — for homogeneous materials (sugar, salt, sand) typically ±1-2%, for variable materials (mixed scrap, recyclate) ±3-5%.
We perform a one-off density calibration on commissioning and the system continuously cross-checks against weighbridge data if you have one — drift below 0.2%/year in normal operation.
How do you measure bulk material on a conveyor belt?＋
Bulk material on a conveyor belt is measured by mounting a 2D-LiDAR across the belt and capturing thousands of cross-section lines per second. From each cross-section — profile shape, height, width — and the known belt speed, the system computes volumetric flow in m³/h. With a calibrated material density, the mass flow in t/h falls out in the same step. The method is contactless, has no mechanical wear and requires no work in the belt line.
Compared to a belt scale, the practical advantages are clear: no belt stop for installation, no calibration marathon with reference weights, no load-cell re-trim after every belt change. The scan additionally delivers a full loading profile — off-centre loading, belt-edge spillage, belt mistracking and clumping are detected as flagged events long before they cause damage. A belt scale gives one number; a LiDAR belt scan gives throughput and conveyor-diagnostic data from a single sensor.
In the OWL EYE® portfolio this is handled by VOLUME FLOW. Reference customers include K+S (salt belts), Nordzucker (sugar-beet intake) and proFagus (wood chips). The full comparison to traditional belt scales is at Why LiDAR.
What does installation on an existing conveyor look like?＋
The 2D-LiDAR cross-scan unit is mounted on a small bracket above the belt — typically 1.5 to 4 m above the material. Mounting takes a few hours per belt and does not require belt downtime if structural side access exists. Wiring is power + Ethernet to the local control cabinet.
Total commissioning time including material calibration is typically one shift per belt. We deliver the bracket pre-fabricated to your belt geometry — no on-site welding required.
How does the data reach our SCADA / SAP / MES system?＋
Three standard interfaces ship out of the box: REST API (JSON over HTTPS), OPC UA server (industry standard for SCADA / PLC), and SAP IDoc connector for ERP. Volume, mass, throughput per minute / hour / shift, alarms — all available in real time.
The dashboard runs in your browser; the raw data lives on our edge server inside your network. No cloud dependency required, no outbound internet connection needed for the production loop.
How is OWL EYE® belt scanning different from a belt scale?＋
A belt scale integrates mass through load cells in the conveyor frame — one number, the total throughput. OWL EYE® belt scanning is a 2D-LiDAR cross-scan above the belt that captures the full load profile every line: shape, height, distribution, edges.
That difference is decisive. A belt scale tells you how much; a belt scan also tells you how it sits — off-centre loading, profile asymmetry, belt-edge spillage, belt mistracking, chute wear. Volume (m³/h) and density-calibrated mass (t/h) come out as a side benefit of the scan.
So: a belt scale weighs. A belt scan gives you flow data and conveyor diagnostics from one contactless sensor — no intervention in the belt line, no frame rebuild, no recalibration cycle. For nearly every retrofit on an existing conveyor, belt scanning installs faster, wears less and delivers more.
What load-profile anomalies can OWL EYE® detect on a conveyor belt?＋
OWL EYE® captures a full cross-section of the load every scan line, so any deviation from the expected profile becomes a flaggable event. In practice the system detects:
- Off-centre loading — the load centre of mass shifts left or right of the belt centreline, a typical sign of a worn or mis-adjusted chute.
- Profile-height anomalies — sudden spikes, dips or hollows that indicate clumping, bridging upstream, or a feeder problem.
- Belt-edge spillage — material climbing or overflowing the belt edge, captured continuously instead of only after a housekeeping round.
- Belt mistracking — the entire profile drifts laterally over many minutes, the earliest visible sign of idler or roller trouble.
- Asymmetric profile shape — the load profile slopes consistently to one side, a tell of skirt-board leaks or worn chute liners.
Each anomaly is configurable: threshold, persistence, hysteresis. Events route into your CMMS, OPC UA, dashboard or e-mail. The result is a conveyor belt load profile monitoring stream that powers preventative maintenance instead of waiting for failure.
How does a 3D belt scan feed preventative maintenance?＋
A 3D belt scan turns a conveyor into a continuous condition source — and continuous condition data is exactly what a preventative-maintenance programme needs.
OWL EYE® streams three classes of signal into your maintenance system:
- Instant anomaly events — off-centre loading, spillage, profile spikes. Each event is timestamped and routed to your CMMS or OPC UA contact for an interlock or work order.
- Slow-drift trends — gradual lateral profile drift indicates belt mistracking; gradual asymmetry indicates chute or skirt wear. The trend appears days or weeks before a visible failure.
- Throughput-vs-profile baselines — for a given material and feed rate the profile shape is repeatable. Deviations from baseline correlate with chute wear, feeder issues and bunker discharge problems.
Combine those streams with your maintenance plan and conveyor stops shift from reactive to condition-based: the work order is generated before the breakdown, not after. That is preventative maintenance built on data the belt scale, switch and walk-down can never deliver.