Vapor Quality Sensor in Strainer Housing

Category: HBX-CR-ST / HBX-DX-ST

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.

Vapor Quality Sensor in Strainer Housing
With a vapor quality sensor integrated into a standard strainer house you are ensured safe functionality and easy installation of the sensor. The butt weld connection makes it easy to weld with same size of piping. Please be aware that the flow direction of the vapor quality sensor is opposite of the flow direction when used as a strainer. If installed with wrong flow direction functionality will NOT be correct.

Besides the benefit of easy installation this solution makes it easy to dismantle the lid with the sensor conductor and clean it if necessary.

The sensor integrated into standard strainer housing is available in both carbon steel DN20 to DN300 and stainless steel DN20 to DN65. Ask for availability if size outside of this range is requested.

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


Flooded system:

HBX ST flooded applikationstegning

Optimum efficiency at all loads is obtain by measuring the Vapor Quality in the outlet of the evaporator and use the signal to change the height of the driving head as shown, lower level will minimize the liquid amount  in the evaporator and secure balanced and dynamic evaporation  during part load and thus optimum heat transfer.

The HBX-OVC-ST Vapor Quality control signal (cable out, 4-20mA) is connected to DI 3 (pin 3) on the HBSLC liquid level sensor and used to change the desired set value for the liquid level in the recirculation vessel/separator.


DX System:

Aptegning DX web 1000px



Technical data:


Connection Diagram





 Danfoss Strainer DN20 DN65 profiltegninger WEB


Tabel Dimensioner DN20 DN65





Danfoss Strainer DN65 DN200 profiltegninger WEB

 Tabel Dimensioner DN80 DN200

Danfoss Strainer DN250 DN300 profiltegning WEB

Tabel Dimensioner DN250 DN300

Strainer small

In the sizes DN20-DN40 the strainer is extended with a 100 mm tube.

Power supply
Voltage24 V AC/DC 
Current consumptionMax 250 mA
Electronic connectionM12, 5 pins
Analog signal4-20 mA
ControlBuild in controller for valve (optional)
Environmental conditions
RefrigerantsApplicable to HC, HFC/HFO, NH3, CO2
Temperature range–60°C/+150°C (–76°F/+302°F).
Max. Working pressure52 barg (754 psig).
Degree of protectionIP65
Vibrations IEC 68-2-6 (4g) 
Mechanical specifications
Welding connectionButt weld
Material liquid partsAISI 304 / PEEK Carbon Steel
Material - electronic partsGF BLK, Nylon 6 (PA)
SizeSee drawing and table
WeightSee ordering codes
TypeFront house
EMC testEN 61000-2
5 m cabel with. M12 plugHBxC-M12/5 
Cabel specificationsPUR -5 x 0,34mm2 
LED indicationLED (green, yellow og red)
ConfigurationWith HB Tool
Valve control (Modulating valve)
Signal to valve4-20 mA
Valve regulationPI-regulation
Valve control (PWM)
Signal to valve24V AC/DC
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
* Total consumption is sensor consumption plus output and it depends on ambient temperature.

Ordering code

Pipe diameterStainless steelCarbon steelOrdering code
DN 20 (3/4”)AvailableAvailableHBX-ST*
DN 25 (1”)AvailableAvailableHBX-ST*
DN 32 (1 1/4”)AvailableAvailableHBX-ST*
DN 40 (1 1/2”)AvailableAvailableHBX-ST*
DN 50 (2”)AvailableAvailableHBX-ST*
DN 65 (2 1/2”)AvailableAvailableHBX-ST*
DN 80 (3”)On requestAvailableHBX-ST*
DN 100 (4”)On requestAvailableHBX-ST*
DN 125 (5”)On requestAvailableHBX-ST*
DN 150 (6”)On requestAvailableHBX-ST*
DN 200 (8”)Not availableAvailableHBX-ST*
DN 250 (10”)Not availableAvailableHBX-ST*
DN 300 (12”)Not availableAvailableHBX-ST*
* 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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