Vapor Quality Sensor, Inline

Technical data: HBX-CR-IN / HBX-DX-IN 

The Vapor Quality Sensors have a new innovative technology which makes it possible to measure the mix between gas and liquid in a refrigerant from 0% gas to 100 % gas - a measurement no other sensor can provide. It consists of a tube, with metal inserts, where the mix of two phases pass through. The sensor measures the dielectric constant of the fluid, and as two different phases (liquid/gas) has different dielectric constant, the mix between the two, can be calculated. The output of the sensor is the “X” value which has a linear relation to the Volume % of liquid in the gas

The sensor offers very precise measurements and provides instant read-outs of the gas quality, making it useable in most evaporators (plate, pipe, and air evaporators).
The sensor’s microprocessor also functions as a controller, enabling the direct control of a modulating motor valve, thereby bypassing the external controller or the PLC. The controller can be set up with all the parameters that are necessary for regulating a modulating motor valve or a stepper motor valve. The sensor is available with a cable for direct supply to and control of the motor valve, or as a sensor where the signal is sent to the external controller/PLC.

All vapor quality sensors are suitable for controlling both DX, semi flooded and flooded operation.

Leakage detection for ammonia CO2 cascade systems
The vapor quality sensor can detect ammonia carbamate which is formed when CO2 leak into ammonia. The sensor can be used for both leakage detection and control an evaporator at the same time or just serve as leakage detector. The alarm can both be provided as a digital alarm and via the analog output. For shell and tube heat exchangers the HBAC is normally used.

The straight version called Inline is available from 1” to 2” and the sensor accepts flow in both directions. The pressure loss in the sensor is very low due to the straight flow and smooth internal design. Mounting can be both horizontal and vertical position. The sensor is made in stainless steel and can be butt welded (TIG) or brazed into the system.

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Product features

Measures the volumetric concentration of gas in a gas/liquid mixture
Balanced evaporator control to achieve semi-flooded operation with high heat transfer
Able to control an expansion valve directly with simultaneously analog 4-20mA output to a PLC
Can be used to optimize and control both DX systems and overfeed systems
Instant measurement and analog output
Can be used for all common refrigerants


HBX DX Inline web


Connection Diagram




Maal HBX Inline



Power supply
Voltage24 V AC/DC 
Current consumptionMax 250 mA
Electronic connectionM12, 5 pins
Analog output4-20 mA
LED indicationGreen, yellow, and red
Environmental conditions
Ambient temperature-30...+50°C
Refrigerant temperature-60...+80°C
Max. pressure100 bar 
Degree of protectionIP65
Vibrations IEC 68-2-6 (4g) 
Mechanical specifications
Material - mechanical partsAISI 304 / PTFE
Material - electronic partsNylon 6 (PA)
DimensionsSee drawing
EMC testEN 61000-2
Cable specification (power supply)
Cable size5 m - 5 x 0.34 mm2 
Cable glandsPG7 / M8
Cable resistance500 Ohm/Km  
Configuration HB Tool
Tool to be used HBX software
Valve control (Modulating valve)
Signal to valve4-20 mA
Valve regulationPI-regulation
Valve control (PWM)
Signal to valve24V AC/DC
PWM period0-120 s (default 6 s.)
Valve control (Stepper motor)
Stepper motor steps25-5000 steps
Stepper motor speed2-40 m/s
Stepper motor phase current0-750 mA
Stepper motor holding current0-250 mA
Cable specification (valve control)
Length3 m (118”)
Cable size3 x 0.75 mm2
Cable glandsPG7 / M8

Ordering code

Pipe diameterStainless steelOrdering code
DN 25 (1”)AvailableHBX-IN*
DN 40 (1 1/2”)AvailableHBX-IN*
DN 50 (2”)AvailableHBX-IN*
* This list shows the sizes and steel types available. The ordering number is not complete until the desired specifications for the product is filled in in the "Product Specification Form" (see below).
For inquiries and orders please fill in the "Product Specification Form" (find it under the "downloads" tab on this product page) and e-mail it to


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