Liquid Level Sensor - ATEX

Product series: HBLT-Flex

HBLT-flex is a sensor for measurement of liquid level in gas applicable in HC, HFC, HFO & CO2. HBLT-flex is a capacitive sensor suited for industrial systems. The sensor has an output signal of 4-20 mA, which is proportional with 0 and 100%.
HBLT-flex can be adjusted in length to fit the current application. The sensor element consists of a 4 mm steel wire with aluminum pipe elements and plastic washers. The sensor can be supplied up to 2 m length and can be shortened to fit the application. The sensor must be installed in a pipe with a diameter between 25 and 32 mm (1”-1 ¼”) to get sufficient sensitivity. HBLT-flex can be used in connection with the HBLT-C1 controller for controlling pumps. It is designed to control liquid levels in both low pressure and high pressure systems.

It emits a 4-20 mA signal, which is proportional to the sensor's set range of measurement. The sensor is designed in stainless steel and can be used in corrosive environments. The sensor 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 sensor is a 2-wire design with analog output with 4 mA (empti tank) and 20 mA (full tank). The analog output shall be connected to the Ex-barrier. The Ex-barrier is not sccope of supply.  

The sensor can be set-up for liquid type in the HB-Tool which can be downloaded from our web-page. See HB-Tool. 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: -40...+70°C.
  • Max pressure: 150 bar
  • ATEX / IECEx: Ex ia  IIC T1…T6 Ga (Ta = -40°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. 



  • Process plants
  • Storage tanks

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 HBLC sensor is designed for many kinds of liquidsbased on the dielectric constant. The liquid type is selected in the HB-Tool. 

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:

Sensor type                Liquid type                                                                                                   Dielectric constant

HBLC-CO2                CO2(R744), Butane (R600), Isobutane (R600A), Propane (R290)             1.5-2.0
HBLC-OIL                  PAO oil, Mineral oil, POE oil, PAG oil                                                          2.0-4.0
HBLC-HFC                R507, R410a, R407c, R404a, R22, R32, R134a, R1234yf, R1234ze         4.0-10.0
HBLT-A2                    NH3, Water, R717, R718, Alchohol                                                             10.0-80.0



Connection diagram

Diagram sensor


The sensor can be programmed to either emit a linear signal, which is identical to the tank level, or to regulate a valve for the purpose of obtaining the same level in the tank (float valve).



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 (AO)
Mechanical specifications
Material liquid partsAISI 304 / PTFE
Material electronic partsNylon 6 (PA)
Environmental conditions
Max pressure150 bar
Protection degreeIP65
VibrationsIEC 68-2-6 (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

LengthThread typeATEX/IECEx approvalOrdering code
300 mm 3/4" NPTZone 1HBLT-FLEX-3-2-Z1
300 mm 3/4" BSPPZone 1HBLT-FLEX-3-6-Z1
600 mm 3/4" NPTZone 1HBLT-FLEX-6-2-Z1
600 mm 3/4" BSPPZone 1HBLT-FLEX-6-6-Z1
800 mm 3/4" NPTZone 1HBLT-FLEX-8-2-Z1
800 mm 3/4" BSPPZone 1HBLT-FLEX-8-6-Z1
900 mm 3/4" NPTZone 1HBLT-FLEX-9-2-Z1
900 mm 3/4" BSPPZone 1HBLT-FLEX-9-6-Z1
1200 mm 3/4" NPTZone 1HBLT-FLEX-12-2-Z1
1200 mm 3/4" BSPPZone 1HBLT-FLEX-12-6-Z1
1400 mm 3/4" NPTZone 1HBLT-FLEX-14-2-Z1
1400 mm 3/4" BSPPZone 1HBLT-FLEX-14-6-Z1
1600 mm 3/4" BSPPZone 1HBLT-FLEX-16-6-Z1
1600 mm 3/4" BSPPZone 1HBLT-FLEX-16-6-Z1
1800 mm 3/4" BSPPZone 1HBLT-FLEX-18-6-Z1
1800 mm 3/4" BSPPZone 1HBLT-FLEX-18-6-Z1
2000 mm 3/4" BSPPZone 1HBLT-FLEX-20-6-Z1
2000 mm 3/4" BSPPZone 1HBLT-FLEX-20-6-Z1
300 mm 3/4" NPTZone 0HBLT-FLEX-3-2-Z0
300 mm 3/4" BSPPZone 0HBLT-FLEX-3-6-Z0
600 mm 3/4" NPTZone 0HBLT-FLEX-6-2-Z0
600 mm 3/4" BSPPZone 0HBLT-FLEX-6-6-Z0
800 mm 3/4" NPTZone 0HBLT-FLEX-8-2-Z0
800 mm 3/4" BSPPZone 0HBLT-FLEX-8-6-Z0
900 mm 3/4" NPTZone 0HBLT-FLEX-9-2-Z0
900 mm 3/4" BSPPZone 0HBLT-FLEX-9-6-Z0
1200 mm 3/4" NPTZone 0HBLT-FLEX-12-2-Z0
1200 mm 3/4" BSPPZone 0HBLT-FLEX-12-6-Z0
1400 mm 3/4" NPTZone 0HBLT-FLEX-14-2-Z0
1400 mm 3/4" BSPPZone 0HBLT-FLEX-14-6-Z0
1600 mm 3/4" BSPPZone 0HBLT-FLEX-16-6-Z0
1600 mm 3/4" BSPPZone 0HBLT-FLEX-16-6-Z0
1800 mm 3/4" BSPPZone 0HBLT-FLEX-18-6-Z0
1800 mm 3/4" BSPPZone 0HBLT-FLEX-18-6-Z0
2000 mm 3/4" BSPPZone 0HBLT-FLEX-20-6-Z0
2000 mm 3/4" BSPPZone 0HBLT-FLEX-20-6-Z0


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