RHF series

Ring heat flux sensors

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The RHF series consists of customer-specific heat flux sensors incorporated in a stainless steel ring. They are used as building blocks in larger measuring systems, for example to study fouling and slagging in combustion processes. Many RHF’s are eventually part of so-called “deposition probes” or “fouling sensors” designed by the customer. It is particularly suitable for trend monitoring that is necessary for this application. A typical sensor contains 4 separate heat flux and 4 temperature sensors, so that fouling behaviour can be studied at different locations on the sensor at different angles relative to the local gas flow.


Sensors of the RHF series are used in scientific as well as operational experiments to study fouling and slagging behaviour. RHF may be employed as a building block, when designing a deposition probe or a fouling sensor. Many RHF sensors are part of multi-purpose probes that also measure local gas temperature and take gas samples (so-called suction probes). RHF’s can be manufactured in many different geometries and dimensions. RHF01 is a version incorporating 4 heat flux / temperature sensors. Usually the RHF is cooled by compressed air or water. Using RHF has the advantage that the sensor is small, so that multiple sensors fit in one tube, providing “directional” information. Also the RHF has a fast response. Hukseflux is specialised in design and manufacturing of slagging and fouling sensors. RHF design is user-specific; geometry and cabling are designed in cooperation with the user for the specific application. We can also build your entire deposition probe.

Click on drawing in Gallery for dimensions of a RHF series example: RHF01 ring heat flux senor consists of four temperature / heat flux sensors (1), in a stainless steel housing (2), with either flat connection for welding- (3) or alternatively threaded connections (4). Metal sheathed wire (5) is usually extended with PTFE wire (7). Dimensions in the drawing are only serving as example. All dimensions are in mm.


RHF is most suitable for relative measurements using one sensor, i.e. monitoring of trends relative to a certain reference point in time or comparing heat flux at one location to the heat flux at another location. The heat flux sensor calibration depends on the way the sensors are built-in and may also depend on the flow rate of the gas or liquid used for cooling. RHF01 is provided with a factory calibration of every sensor which is suitable for relative measurements. If you want to perform accurate absolute measurements with RHF, as opposed to relative measurements, it is necessary to calibrate the RHF incorporated in the final design under operating conditions, possibly as a function of water or air flow. Hukseflux can provide dedicated heaters to perform such calibration.

Suggested use

  • building block for customer-specific sensors
  • deposition sensors
  • fouling sensors
  • heat flux sensors


  • heater for calibration


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