Hot Metal Detectors (HMD)Back to list ›

Scanning Hot Metal Detector with Laser Pointer
Rota-Sonde DC4000L

  • Two sensitivity ranges : 400 °C and 230 °C
  • Laser pointer for easy alignment
  • Remote control of the sensitivity
  • Self-monitoring


Scanning hot metal detector with 2 sensitivity ranges and laser pointer.


  • Easy alignment of the sensor with integrated laser pointer
  • Assured detection regardless of the transverse position of the product
  • Precise detection thanks to the narrow lateral field
  • Reliable detection even in the presence of steam or dust thanks to the small analysing beam
  • Photosensitive cell that best suits application in rolling mills, despite scale and steam
  • Very low maintenance, virtually nil in some cases


The Rota-Sonde DC4000-L is a scanning hot metal detector for continuous caster and rolling mill applications, offering two sensitivity ranges and two self-monitoring functions.
The "high sensitivity" range enables detection of steel product at a temperature as low as 230 °C.
In this way, the Rota-Sonde DC4000-L is convenient for all hot metal detection applications in the Steel Industry and its self-monitoring facility optimises preventive maintenance.

Examples of applications

The Rota-Sonde DC4000-L is perfectly suitable for all detection applications of low-temperature rolled product or low emissivity materials such as hafnium.
It is also convenient for applications where a change in the process or material leads to major variations in the temperature of the product or its emissivity, as after quenching, or for special steels, etc...


If the apparent temperature of the material is uncertain during the design stage, the choice of the sensitivity range of the Rota-Sonde DC4000-L can be left to the time when it is commissioned.



The Rota-Sonde DC4000-L is a scanning sensor, which is sensitive to the infrared radiation emitted by hot products.
It is a self-contained detector including :

  • An optoelectronic case with a protecting hood of the viewing port and a connector.
  • A cooling plate with an adjustable mounting stand.

Because of its design and particularly its cast aluminium case, the Rota-Sonde DC4000-L is specially adapted for the harsh environment of the Steel Industry (shocks, vibrations, heat, vapour and dust).

Operating principle

• 1. Scanning system

The detection field is scanned by a rotating polygonal mirror which reflects the infrared radiation from the product to the photocell.


Because of the exclusive optical scanning principle, the Rota-Sonde DC4000-L offers the following advantages :

  • Easy alignment and reliable detection, regardless of the transverse position of the product, thanks to the large vertical field angle.
  • Accurate detection because of the narrow lateral field.
  • Reliable detection due to the small analysing beam.

All these features give accurate and reliable detection, whatever the dimensions and the temperature of the product, or its distance and its position in the scanned field.

• 2. Photosensitive cell

The Rota-Sonde DC4000-L is fitted with a special photosensitive cell, the best compound for detection of metal, even at a temperature as low as 230 °C (455 °F).



The Rota-Sonde DC4000-L is enclosed in a sealed cast aluminium case.
A hood to protect the window glass is fitted with an air-jet facility to blow a vertical air curtain in front of this glass; the protective hood can be hinged down to clean the window.
The case is mounted on a cooling plate including a stainless steel pipe and fixed to a mounting stand, adjustable in two axes.
The water and air purging connections are on the support plate.
In this way it is possible to remove the sensor without first disconnecting the water and air supplies and without need of optical re-alignment.



  • Sensitive photocell with a better detectivity factor at low temperatures and in the presence of water vapour.en-dc4000-l-009-800x600
  • Two sensitivity ranges with remote selection.
  • Laser pointer for easy alignment.
  • Case mounting connector and mating connector fitted with high temperature cable.
  • Plug-in circuit.
  • Control panel behind a hinged cover and including :
    • Two sensitivity setting potentiometers (one for each range).
    • A TEST button to control a built-in lamp for simulation of the presence of hot product in the field and to switch on the laser pointer.
    • A three-colour LED :
      Green      :     product absent
      Red          :     product present
      Orange   :     cell signal saturated
      Off           :     alarm


Self monitoring functions

In order to optimise preventive maintenance and to improve reliability, the Rota-Sonde DC4000-L offers self monitoring functions including :

  • Monitoring of the excessive internal temperature (limit of 55 °C / 130 °F) indicating a fault in the cooling system.
  • Monitoring of the photocell signal to indicate dirt on the window or incorrect sensitivity setting.
  • Alarm indicating power supply or scanning defect.

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