Oil Level Switch - Low Temperature

Technical data: HBSO-LT-Z - Temperature range: -30..+70°C

HBSO is a level switch for detecting common lubricating oils in gas and air. Typically, it is installed in/on the compressor and the oil separator, but it is also suited for installation in other locations where you like to detect oil. The sensor's measurement principle makes it unique for these purposes, since the properties of the measurement principle allows it, among other things, to detect oil without detecting ammonia or water. It is calibrated so that it is unaffected by oil spray and only allows a small amount of foam. The sensor is constructed to resist high pressure and temperatures. For oil temperatures above 60°C (140°F) the HBSO-MT or HBSO-SSR /HT must be used.. The switch must be supplied with 24 V DC through an Ex-barrier, which must be an approved and certifided galvanically isolated interface barrier placed outside the hazardous area. The switch is a 2-wire design with analog output which either will be 4 (no liquid detection) or 20 mA (liquid detection). The digital input shall be connected to the Ex-barrier. The Ex-barrier is not sccope of supply.  

The sensor can be set-up for oil types in the HB-Tool which can be downloaded from our web-page. See HB-Tool. It is as well possible to switch from NO yupe to NC type in the program. Diagnostic is as well a possibility with the tool. The programming must be carried out in an non hazardous area. 

The sensor range include sensors for zone 0 and 1 according to ATEX/IECEx. The sensors can be used in device category 1G and temperature class T1...T6.   

A 5 m cable with M12 plug type IEC61076-2-101 is included.    

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Product features

  • Temperature range -30...+70°C.
  • Max pressure: 150 bar
  • ATEX / IECEx: Ex ia  IIC T1…T6 Ga (Ta = -30°C to +70°C) 
  • Excellent liquid and gas compatibility 
  • Cost effective alternative to ultrasonic & radar sensor technologies 
  • Works with reflective liquids 
  • Will not fail due to vapor 
  • No galvanic corrosion or risk of bacteria 
  • Split design which makes it easy to install and make diagnostic. 
  • Clear LED indication.




  • Process plants
  • Storage tanks
  • Compressors
  • Pumps

Intrinsically Safe design:

Intrinsically Safe (IS) sensors are designed and wired to work on such a low current and voltage that it cannot possibly ignite flammable material. By limiting the energy available within the defined hazardous area, electrical equipment can operate safely even amid hazardous mixtures of gasses.

The measuring principle and the influence of the dielectric constant:

Capacitors are designed with minimum two conductors, where one of them is electric isolated. The dielectric constant are key for operation of capacitors, the capacity size is measured in pF.

Dielectric constant (Relative permittivity) is a unique value on a scale of 1 to 100. The value can be seen as a media’s DNA, because it`s unique and related to the molecular structure and polarization.

The Dielectric Constant is always greater than or equal to 1. The larger the dielectric constant, the more charge can be stored (like a battery).

The dielectric constant changes with temperature and pressure, the sensor comes with automatic temperature compensation calibrated/adapted to the measured media.

Type of switches:

Switch type                Liquid type                                                                                                   Dielectric constant

HBSC                        CO2(R744), Butane (R600), Isobutane (R600A), Propane (R290)             1.5-2.0
HBSO                        PAO oil, Mineral oil, POE oil, PAG oil                                                          2.0-4.0
HBSH                        R507, R410a, R407c, R404a, R22, R32, R134a, R1234yf, R1234ze         4.0-10.0
HBSR                        NH3, Water, R717, R718, Alchohol                                                             10.0-80.0


Connection diagram

Diagram switch 




HBSO ex 2 

HBSOx-xxx/xx-1 (-2, -5 & -6)

HBSO ex 7 



Power supply
Voltage12-28 V DC two wire
Max. current consumption Max 20 mA
Plug connectionsM12, 5 pins - DIN 0627
Signal output 4 / 20 mA (DO - Open/Closed)
Contact functionNO or NC ( Open = 4 mA / Closed = 20 mA)
Mechanical specifications
Material liquid partsAISI 304 / PTFE
Material electronic partsNylon 6 (PA)
Environmental conditions
Max pressure150 bar
Protection degreeIP66
VibrationsIEC 60068-2-6 (4g)
EMCEN 61000
Ex area
IECEx classificationEx ia IIC T1…T6 Ga
Device category1G for Zone 0 & 1
Type of protectionia
Gas resp. gas groupIIC
Temperature classT1….T6
Ambient temperature-40...+50°C/+70°C
When used in Ex-area the installation has to be carried out according to standards in force for the country in question.
The Equipment must be installed via an approved and certified galvanically interface barrier placed outside the hazardous area.

Ordering code

OutputThread typeOrdering code
Temperature Range: -30..+70°C
Spare parts for HBSO
Electronic part for HBSO-NO-LT-EX HBSO-EL-NO-LT-ZO
Electronic part for HBSO-NC-LT-EX HBSO-EL-NC-LT-ZO