Optoelectronic level monitoring

Optoelectronic level monitoring

In numerous applications for level monitoring of liquid media, the use of float switches is prohibited. Typical applications are contaminated media and turbulence in the medium, which can block the float. In these cases, optoelectronic level sensors are often used.


Optoelectronic level monitoring has the following advantages:

  •  No mechanically moving parts

  •  PNP transistor output

  •  High accuracy (± 0.5mm)

  •  Compact design

  •  Very good price-performance ratio

Schmidt Mess- und Regeltechnik offers you a comprehensive portfolio for these applications:

 OG 01OG 02OG 04OG 05OG 051OG 052
Applicationsstandardstandardrefrigeration techiniquehigh
Ex areascommercial vehicles and marine engines
Special featurescompact designswitch length up to 3000mmprismatic glass melted into the steel housingup to 170°C, optional higherwith Atex approvalvibration and temperature shock resistant
Pressure max.10 bar25 bar40 bar, optional higher25 bar25 bar25 bar
Medium temperature max.100°C100°C-40°C ... +100°C170°C, optional higher135°C130°C, optional higher
Approvals    Atex, IECGerman Lloyd


For standard applications OG 01 and OG 02

Optoelectronic level sensor OG 01 for standard applicationsWe use devices OG 01 and OG 02 for standard optoelectronic applications (liquids such as oils, water, distilled water, aqueous media, for foam detection).
Optoelectronic level sensor OG 52

Applies to both devices:

  • Temperature max. 100°C

  • Accuracy ±0.5mm

  • No moving parts

  • Function independent of position

  • Responsiveness adjustable

  • High compressive strength (OG01: up to max 10 bar, OG02: up to max 25 bar, optional higher)

OG 02 is also available with freely selectable switch lengths from 65 mm to 3,000 mm. This enables an optimal adaptation to the application-specific requirements.


For refrigeration technique OG 04

Optoelectronic level sensor OG 04 for refrigeration techniqueThis sensor can be used with various refrigerants. The prismatic glass is melted into the steel housing, there are no seals. Therefore, no attack by the refrigerant is possible.


Further features:

  • High pressure resistance, up to 40 bar, optionally up to 100 bar

  • Can be used down to -40 °C

  • Responsiveness adjustable


For high temperatures OG 05

Optoelectronic level sensor OG 05, for high temperaturesThe OG 05 was developed for particularly high media temperatures. It can be used in a range from -40 to 170 °C. On request, we also supply special versions for the range above 170 °C.
For these applications, the OG 05 is equipped with a stainless steel housing.



For Ex areas OG 051

Optoelectronic level sensor OG 051 for Ex areas

New at Schmidt Mess- und Regeltechnik: The optoelectronic level sensor OG 051 is designed as an explosion-proof version for zones 0 and 1 (ATEX approval according to protection type II1 / 2G Ex ia IIC T4Ga / Gb) for medium temperatures up to 135 ° C.

The parts of the housing that come into contact with the medium are made of stainless steel. The prism material is borosilicate glass. The device can be supplied with numerous fastening threads (G ⅜“, G ½“, NPT ½ “, M18x1,5 M12x1, M12x1,75, M14x1,5, M14x1,75).


Current switching output:
Supply -7.5 … 30 V DC
Low: >4mA up to <10mA; High: >12mA up to 18mA
Errors: <4mA, >20mA


For commercial vehicles and marine engines OG 052

Optoelectronic level sensor OG 052  for commercial vehicles and marine enginesSpecial features:
The optical level switch type OG 052 is characterized by its extremely good mechanical and electronic stability as well as the high temperature shock resistance, reliability and its exact switching accuracy even at high temperatures.
Due to the compact design, installation is possible even in confined spaces.
The OG 052 was certified by Gemanischer Lloyd for shipbuilding applications.

Further festures

  • Robust design, made of stainless steel

  • Vibration and temperature shock resistant

  • Media temperature max. 130 °C, pressure 25 bar

  • Approval: German Lloyd

The OG 052 was developed for extreme operating conditions and is often used for oil detection in commercial vehicles, machine tools, construction machines, agricultural machinery, rail vehicles, compressors, pumps, hydraulic units and motors.