Strainer Housing - Vapor Quality Sensor

Category: HBX-DX-ST & HBX-CR-ST for DX and Overfeed systems - ATEX/IECEx Certified 

HB products has developed the unique vapor quality sensor, which is the only sensor able to directly measure the liquid content of liquid in the evaporator output. The sensor works both in pump circulated and DX systems and can optimize the efficiency and capacity to a new level.

Evaporator control
The optimal evaporator is not filled with liquid refrigerant like you often have in pump circulated refrigerant systems with circulation ratios above 1.5. The optimal evaporator is not dry like a lot of superheat-controlled evaporators.
By measuring the liquid content in the evaporator output and using this measurement to control the liquid feed.

Most refrigeration systems operate most of the time in part load and especially during part load the efficiency is typically rather poor and can be optimized significantly. Pump circulated systems fills the evaporator with liquid which reduce heat transfer by 50 % and increases the pressure loss which increase energy consumption. For pump circulated systems an energy saving of minimum 20% is typical for optimized systems, and much more on systems without circulation control.

In DX systems a larger part of the evaporator is used for superheating and the superheat is increased which reduce capacity and increase the power consumption dramatically. We have documentation showing an energy saving of 20% during full load and 50% during part load for a DX ammonia system. Link to the documentation.

Strainer house version
With a vapor quality sensor integrated into a standard strainer house you are ensured safe functionality of the sensor and easy installation. The butt-welded 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.

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.

Product selection guide
To find the right part number to purchase please use our selection guide in the shop (link below), product overview under "ordering code" or send our Product Manager Henrik Kudsk a system description and he will guide you to the right part number. Please use the "Product Specification Form" (find it under the "downloads" tab on this product page) and e-mail it to   

Shop image

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
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:
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.



Connection Diagram

Diagram sensor


 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
Voltage12-28 V DC two wire
Max. current consumption Max 20 mA
Plug connectionsM12, 5 pins - DIN 0627
Signal output 4....20 mA (AO)
IECEx classificationEx ia IIC T1…T6 Ga
Device category1G for Zone 0 & 1
Type of protectionia
Gas resp. gas groupIIC
Temperature classT1….T6
Mechanical specifications
Ambient temperature-40...+50°C/+70°C
Max pressure100 bar
Protection degreeIP65
VibrationsIEC 60068-2-6 (4g)
Environmental conditions
Material liquid partsAISI 304 / PTFE
Material electronic partsNylon 6 (PA)
Outsite dimensions210 x 51 x 72 mm
Weight500 g
Ex area
EMCEN 61000

Ordering code

Pipe diameterRefrigerantDesignMaterialATEX/IECEx approvalOrdering code
DN20NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D20-EX
DN25NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D25-EX
DN32NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D32-EX
DN40NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D40-EX
DN50NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D50-EX
DN65NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D65-EX
DN80NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D80-EX
DN100NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D100-EX
DN125NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D125-EX
DN150NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D150-EX
DN200NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D200-EX
DN250NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D250-EX
DN300NH3, HFC, HFO & CFCDXCarbon Zone 0 & 1HBX-CR-ST-D300-EX
DN20NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D20-S-EX
DN25NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D25-S-EX
DN32NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D32-S-EX
DN40NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D40-S-EX
DN50NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D50-S-EX
DN65NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D65-S-EX
DN80NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D80-S-EX
DN100NH3, HFC, HFO & CFCDXStainless Zone 0 & 1HBX-CR-ST-D100-S-EX
DN20CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D20-EX
DN25CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D25-EX
DN32CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D32-EX
DN40CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D40-EX
DN50CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D50-EX
DN65CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D65-EX
DN80CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D80-EX
DN100CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D100-EX
DN125CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D125-EX
DN150CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D150-EX
DN200CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D200-EX
DN250CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D250-EX
DN300CO2, Butane & ProbaneDXCarbon Zone 0 & 1HBX-CR-ST-T-D300-EX
DN20CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D20-S-EX
DN25CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D25-S-EX
DN32CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D32-S-EX
DN40CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D40-S-EX
DN50CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D50-S-EX
DN65CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D65-S-EX
DN80CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D80-S-EX
DN100CO2, Butane & ProbaneDXStainless Zone 0 & 1HBX-CR-ST-T-D100-S-EX