Vapor Quality Sensors

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 pumped 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.

Sensor variants
We have different versions of the sensors suited for different systems and especially suction pipe sizes. The sensors must be installed at the evaporator outlet to get the fastest response and avoid the risk of liquid built-up between the evaporator and the sensor. It is also very important to install the sensor where it can detect the liquid which typically is at the bottom of a horizontal pipe, but for vertical pipes it can be anywhere. Most of the sensors detect on all sensor walls.

All sensors provides an analog output linear to the gas content in the gas and liquid mix in the evaporator outlet. The measuring signal is instant and has no delay like a temperature sensor used for superheat control.

Direct valve control from the sensor is an option for all models. This feature can reduce the cabling work and save cost, but the control parameters are only available in the sensor and must be modified there.

Compressor protection
This simple version of the sensor is used for detecting liquid in the suction line in front of the compressor. The sensor can deliver an alarm when liquid is detected and a continuous measurement of the liquid content. Both signal can be used to avoid liquid slugging in the compressor which can lead to severe damage.

The interactive table below can help guide you to the different variants.

Product overview


Vapor Quality Brochure
Product Specification Form
Manuals & Guides
Ammonia Brochure
CO2 Brochure