Application> Counting of glass bottles


In the glass bottle production, speed, ambient conditions and often also installation situations are crucial. The detection and counting of bottles of different dimensions and at several manufacturing stages can guarantee a continuous monitoring of the material flow.

After revamping in a German glass factory it was no longer possible to use a retro-reflective light barrier, as the space for the mirror mounting was suddenly missing. During a test on site, a Proxitron engineer mounted a Hot Metal Detector for the detection of hot bottles. It is a compact device that does not require any counterpart, as for example a mirror. Approx. 200,000 bottles of 0.75 l are produced on a single manufacturing line every day. The temperature switch was set on a response temperature of 350 °C. The infrared sensor switches when an object with equal or higher temperature passes in front of it. The connected PLC converts the signal and evaluates it as a bottle.

The infrared sensor showed in practice no restriction in the detection of hot glass objects: neither colour or shape nor production speed could affect counting negatively. Crucial for the success of this application is emissivity of the hot material.

Combined with its accessories, as for example the swivel stand HM 2 for stable mounting, the tube OL 19 for the  field of view limitation and lense protection against dirt - as well as a protection hose for the cable-,  the sensor features reliable, maintenance-free operation, which had not been attained before with retro-reflective barriers.

At a glance

  • Maintenance free
  • High temperature resistant
  • Detection of radiation of hot objects even at great distances
  • Self adjusting with Auto-Teach or step switch for response temperature

Technical data OKA

  • Output: PNP normally open
  • PNP normally closed
  • Supply voltage: 10 - 55 V DC
  • Continuous current: 0 - 400 mA
  • Ambient temperature: -20 up to 75 °C
  • Response temperature: 250 °C up to 900 °C
  • Protection class: IP 67
  • Connection: plug M12


  • Swivel stand HM2
  • Tube OL 19
  • Pilot light for adjustment DAK 308 + OL 26
  • Cable in individual lenghts (e.g. 15 m)
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