Liquid Level Sensor - Ammonia

Technical data: HBLT-3W-Wire & HBSLT-3W-Wire

HBLT-3W-Wire and HBSLT-3W-Wire are the latest version of capacitive wire sensors for liquid level measurement. The sensor is typically used in industrial refrigeration systems and other industrial applications. They are useable in ammonia, HFC/HFO/CFC, and water but not in oil, hydrocarbons, and CO2. For these liquids with a low dielectric constant the HBLT-FLEX must be used.

The sensor has no dead zone and can be used for lengths from 250 mm to 4 or 6 m. It must be installed in a standpipe or in a pipe built into a vessel with a diameter from DN 25 to DN100 (1” to 4 “).

Both sensors have a 4-20 mA analog output signal, which is proportional to the liquid level. Its output signal is 4 mA for an empty container and 20 mA for a full container.

The HBSLT has a built-in controller and a cable output supplementing the M12 output. This cable is used for direct valve control. Alternatively, HBLT-W-Wire can be used in connection with the HBLT-C1 controller or a PLC for controlling pumps and valves.

The sensor element consists of a 1.5mm insulated stainless steel wire. The wire is provided in 4 or 6 m length and can be shortened on site with diagonal cutters or other pliers. When cut to length the sensor must be setup to the actual length by using the HB tool.

This latest version has a new counterweight where the wire pass through without electrical connection. This construction ensures a linear measurement all the way from the end of the wire below the counterweight to the top.

If the sensor must be used in water or other liquid conducting fluids and high accuracy is needed a special kit is needed. The function of the kit is to close the open end of the wire to eliminate the electrical contact. 


Shop image

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 
  • 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).


HBLT Wire ex

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 pressure100 bar
Protection degreeIP65
VibrationsIEC 60068-2-6 (4g)
EMCEN 61000
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
250-4000 mm 3/4" NPTZone 1HBLT-W3-Wire-2-EX
250-4000 mm 3/4" BSPPZone 1HBLT-W3-Wire-6 -EX
250-6000 mm 3/4" NPTZone 1HBLT-W3-Wire-6-2-EX
250-6000 mm 3/4" BSPPZone 1HBLT-W3-Wire-6-6-EX
Electronic part for HBLT-W3-Wire-EXZone 1HBLT-W3-Wire-EL-EX
1"BSPP -> 3/4"BSPP adapter with alu gasket HBS/ADAP/8/6
Weight for HBLT-W3-Wire HBLT-W3-WIRE-PLUMB