More than sensors+automation

JUMO NESOS R04 LS – Float Switch in Curved Version (408304)


  • Point level measurement via floats and reed contact
  • High switching voltage (up to 230 V AC/DC) and high switching current (up to 1.5 A)
  • Different electrical and process connections available
  • Mounting through the tank wall and lock nut
  • Large temperature range for mediums from -52 to +240 °C
  • Guide tube length up to 200 cm
  • High protection type up to IP68
  • Available with optional Pt100, Pt1000, or temperature switch
  • Approvals for explosion-proof areas (intrinsically safe and pressure resistant enclosure)
  • Up to 5 switching outputs are user-definable as normally open contact, normally closed contact, changeover contact, or bistable contact

Customer benefits

  • Proven, maintenance-free measuring principle – the switching operation takes place without contact or auxiliary energy and is therefore wear-free
  • Customer-specific solutions possible – many materials and forms are available for the float; in-house manufacturing of the float with a high production depth
  • Flexible measurement – point level can be determined independently from the container geometry due to the measuring principle
  • Unaffected by media properties such as foam formation, conductivity (permittivity (ε)), pressure, vacuum, steam, and condensation
  • Constant, reliable switching point repeat accuracy over the course of the operating life
  • Quick error check when servicing
  • High degree of chemical resistance due to availability of different materials
  • Cost-effective installation and mounting
  • Maintenance-free
  • Price-performance ratio optimized through the use of standard components and processes


  • Point level measurement of liquids in storage tanks and containers
  • Water and wastewater treatment
  • Food and beverage
  • Chemical
  • Petrochemical
  • Gas and oil
  • Mechanical and plant engineering
  • Energy technology


The point level measurement is carried out according to Archimedes' principle for liquids. The float moves along the guide tube as the level rises or falls. The magnet in the float actuates the reed contact(s) installed in the guide tube with its magnetic field. The switching status of the reed contact can be evaluated and processed through downstream electronic components, relays, or contactors. Depending on the variant ordered, various electrical connections, process connections, guide tube lengths, floats, and number of and positions of contacts as well as their function (SPST-NO, N/O contact/SPST-NC, N/C contact/SPDT-CO, changeover contact/bistable contacts) are available. With the optional temperature sensor or temperature switch, both the point level measurement and the temperature can be acquired via just one measuring point. Variants for monitoring the reed contact temperature are also available.

The switching function always refers to increasing level. The installation is carried out through the tank wall and is fixed via a lock nut.

The float switch is typically used to switch alarms, pumps, signal lamps, valves, and horns via a contact protection relay.
When connecting to intrinsically safe electrical circuits, the intrinsically safe version of the product [Ex i] fulfils the requirements for explosion group II of categories 1/2 G and 1/2 D, as well as 2 G and 2 D. It is therefore suitable for use in the potentially explosive area of zone 0, 1, and 2 for gas (G) and zone 21 and 22 for dust (D). Here, a certified, intrinsically safe isolation amplifier in [Ex ia] must be used.

When connecting to electrical circuits that are not intrinsically safe, the version of the product with flameproof enclosure [Ex d] fulfils the requirements for explosion group II of category 1/2 G and 2 D. It is therefore suitable for use in the potentially explosive area of zone 0, 1, and 2 for gas (G) and zone 21 and 22 for dust (D).
A separate certificate from TÜV SÜD is available for Pressure Equipment Directive 2014/68/EU.

Further technical information is available in the Documentation section.

Prohlášení o shodě / white paper