Belt scales & weigh feeder

The non-contact alternative

We work with you to optimise the measurement of your bulk flow

Place your request for a quotation now and we will be pleased to give you individual advice on your (optical) belt scale application.
Optische Bandwaage Durchflussmessung Massenstrom Volumenstrom berührungslos

Immediate advice: +49 (0) 29 61 – 96 56 86

Kali + Salz AG
Sonntag Baugesellschaft mbH & Co. KG
Wibrek GbR
AGH Steinwerke GmbH

The added value to you


Optical sensors determine the flow rate


Even very short belts, belts with carriers and metallic belts can be measured with high precision


No need for re-calibration in mobile applications


Wireless modem for world-wide data communication


Measures the actual performance and efficiency of your plants


Belt tension does not affect the weighing result


Sensor, electronic unit and interface in one device; fast installation and commissioning

Why is the optical belt scale the right choice for my plant?

With the benefit of our many years of experience we help you to select the optimum measurement system for your application.

Place your request for an offer now and we will be pleased to help you:

+49 (0) 29 61 – 96 56 86

You are probably familiar with the following situation:

Conventional gravimetric belt scales are not suitable for your application or you are seeking an alternative to weight-loaded scales.

You need a precise, maintenance-free flow measurement system for your conveyor belt or would like to calculate the volume stream instead of the mass flow.

The ideal solution:

The optical belt scale offers you non-contact measurement of the product flow (t/h or m³/h) and the volume transported on your conveyor belt.

This measurement system is suitable for belt widths from 600 to 1,800 mm and for practically all types of belts.

Upon request, we will gladly send you a series of information about our products, starting with the access to our data sheets.

How does the optical belt Scale work?

The optical belt Scale records the volume flow on the conveyor belt without contact. The system is equipped with lasers. The number of lasers depends on the belt width.

The laser beams are directed to the surface of the conveyed goods and are reflected back by them. A photo diode detects the reflected laser beams.

The change in the angle of incidence is used to calculate the distance of the conveyed medium from the belt surface and from this the layer height is calculated by triangulation.

The large number of sensors makes it possible to take exact optical measurements of the material profile on the belt. As with a conventional, gravimetric belt scales the speed of the conveyor belt is determined by means of an inductive sensor.

The sensor calculates the actual volume flow from by multiplying the speed of the belt and the cross-section profile detected in high resolution. The calculated volume flow is integrated by the electronic system and is saved as the absolute transported volume.

Different bulk densities can be stored inside the electronics for a variety of products. For this reason, the volume flow (m³/h) for every product can be individually converted into a mass flow.

The collected data are saved in the sensor’s electronics for up to one year. Access is possible via a Bluetooth connection or serial interface.

Bluetooth and a robust mobile phone with specialised software are used to adjust and calibrate the belt scale. In this way, the data can be forwarded and processed by e-mail, Bluetooth or by an USB cable.

For stationary applications there is an analogue output (4 – 20 mA) to transmit the current flow and an impulse output to transmit the absolute volume.

Technical data

Belt widths:
600 to 1,800 mm (larger scales on request)

Dimensions (L x W x H):
663 to 1,815 x 160 x 137 mm

7.1 kg up to 20.7 kg

Power supply:
24 VDC (+/- 20%), 5 A

Operating temperature:
-45°C to +70°C

Measuring points / second:

Measurement accuracy distance measurement:
+/- 0,4 mm

Number of measurement lasers:
13 to 16

Maximum installation height above belt:
Up to 950 mm

Maximum product height on the belt:
Up to 680 mm

Laser class:
IEC 60825-1:2001 class 3b

Pulse power Pmax:
60 mW/laser

Pulse duration /pulse:
400 µs

Laser wavelength λ:
785 nm

Pulse repetition rate:
200 Hz

Data memory:
Up to 1 year

Bluetooth (standard),
Analogue output 4 – 20 mA,
Impulse output,
Serial interface RS-422 (4-conductor)

Frequently asked questions

What levels of accuracy can be obtained with optical belt weighers?
If the device is correctly mounted, the volumetric measurement error is less than 1%. The gravimetric error depends on the accuracy of entry of the product density. Fluctuations in the product density have a direct impact on the measuring accuracy.
What measuring ranges can be covered?
The standard version of the optical belt weigher can measure heights of 400 mm. Maximum performance depends on the belt width and the speed. Performances of more than 1,000 m³/h can be measured without any problem. Minimal resolution is +/- 1 mm for the distance measurement with the lasers.
For what applications are optical belt weighers used?
Balancing material flows, process monitoring, mixing processes, tunnel boring machines. They are frequently used on short or mobile belt conveyors.
What are the requirements for maintenance?
Since there are no moving parts in the device, periodic maintenance is basically not required. In the case of products which produce a lot of dust, the faceplates of the laser and photo diodes should be periodically inspected and cleaned. The scale gives a signal which specific laser should be cleaned or checked.
What are the main components of an optical belt weigher?
The optical belt weigher consists of the sensor head with integral electronics, the holding device and the proximity switch for the measurement of speed. The data are read out by means of a Bluetooth interface on a sturdy „outdoor“ smartphone. The standard setup also includes a compact printer. Alternatively, the data can be transmitted through serial interface, analogue and pulse output.
In which industries are optical belt weighers used?
Optical belt weighers were originally developed for the recycling sector. Mobile crusher and sieving plants are the main locations for use. The measuring principle has also been used in many applications with light cargo, shredded wood, waste and of course, volumetric measurement.
Are modifications in my plant necessary in order to install the system?
As compared to a gravimetric belt weigher, an optical belt weigher can be installed almost without any modification to the feeding mechanisms.
Is calibration of the system necessary?
In every case zero-point calibration is required. In this process, the scale „memorises“ the profile of the empty belt. A control weighing with known volume should be done to achieve the optimal accuracy.

We are delighted to offer personal assistance with your planning
Uncomplicated, individual and practice-oriented