RASI 300C Flue Gas Analyser

The RASI 300C is a compact hand held flue gas and combustion analyser featuring long-life high CO cell and fine draught, ideal for heating engineers working on OIL and GAS appliance and for those servicing and installing BIOMASS boilers.


  • CO (H2 compensated) cell 0-20000 ppm
  • long Life O2 cell
  • Optional NOx measurement
  • Suitable for any type of commercial installations
  • 0.001 mbar fine draught resolution
  • Ideal for BIOMASS boilers
  • Touch screen colour display
  • Standard Bluetooth for communication with mobile app
  • 5 years warranty
  • 4000 data memory


The RASI 300C is a flue gas analysers for heating engineers working on commercial and domestic appliances. It is suitable for making reliable flue gas analysis and combustion adjustment on Gas, Oil and Biomass commercial boilers.

The RASI300C offers many standard features such us memory,blue tooth communication, internal memory, customer data base management which can only be found in much more expensive and industrial grade gas analysers.

We can comfortably say, that the RASI300C is the best price/feature flue gas analyser available in the UK market today.

Sensors and probe
The RASI300C flue gas analyser is equipped as standard with O2 and CO (0-10000 ppm) H2 compensated sensors, temperature and differential pressure measurements and a standard 300 mm triple hose flue gas probe for simultaneous flue gas, draught and temperature measurement measurements.

NOx measurement
The RASI300C is “NOx ready” and can be installed with a 3rd sensor for measuring NO and display NOx measurements. Thanks to our new digital platform, the NO cell can be installed at any time with-out returning the analyser to us.

Fine Draught using same flue gas probe
The RASI300 flue gas analyser is equipped as standard with an high accuracy pressure sensor to provide fine draught measurement with 0.001 mbar resolution. If you are working on BIOMASS BOILERS this is a very important measurement that need to be taken in order to commission or service the system.More importantly, the draught measurement is taken and displayed simultaneously with the gas analysis using the same gas sampling probe. There is no need to change probe.

Plug and Play pre-calibrated field replaceable sensors
rasi300 flue gas analyser plug and play sensorsThe RASI300C flue gas analyser employ our new MMS sensors digital platform, which allow for on site “easy swap” of the measurement sensors with-out sending the analyser to us. The sensor change do not require any calibration because the calibration value are held in the cell electronic. This important feature dramatically reduce the downtime of the analyser in case of sensor failure.

Super easy and quick to use thanks to the simplified touch screen display
web-rasi300–taks-menuThank you to the new smart automatic zeroing of the sensors, the analyser takes only 30-45 second to be ready to use once it has been switched on.

Once the analyser is switched on, the task menu provide the user with the standard and advanced measurement functions with-out the need to scroll between sub-menus. You can also pre-set your preferred configuration that can be recalled every time you need to use it. With a simple touch you can select from:

Gas measurement, let-by test, tightness test, CO ambient , Differential temperature, pressure and so on

High resolution graphical touch screen colour display
Rasi300- let-by and tightness testThe super bright touch screen display presents the data both in numerical and graphical format. Data are very easy to read also in very poor light conditions.

The simplified touch screen display makes the RSI300C flue gas analyser extremely easy to be used.

Powerful data memory, customer management and SD card
The RASI300C flue gas analyser offers many advanced features that can only be found in more expensive gas analysers:

  • Up to 4000 data set on internal memory
  • Export the saved data to SD card in csv format for direct read on a PC
  • View saved data on the RASI300C display
  • Customer management: view or create a customer list, save data under a specific customer and upload your customer list trough the SD card.


O2 measurement 
Range 0 to 25 %
Accuracy ± 0.2 % Vol
Resolution ± 0.1 % Vol
CO measurement with H2 Compensation
Range 0 to 20000 ppm
Accuracy ± 10 ppm or ± 5 % of reading up to 4000 ppm
± 10% of reading from 1000 to 20000 ppm
Resolution 1 ppm
CO2 % ( calculated from O2) 
Range 0 to CO2% Max
Accuracy ± 0.3 % Vol
Resolution 0.1 %
NO measurement (option) 
Range 0 to 5000 ppm
Accuracy ± 5 ppm or ± 5 % of reading up to 1000 ppm
± 10% of reading from 1000 to 5000 ppm
Resolution 1 ppm
Flue gas temperature measurement 
Range – 50 to 1200 °C
Accuracy ± 2 °C
Resolution 0.1 °C
Air Temperature measurement 
Range – 50 to 100 °C
Accuracy ± 1 °C
Resolution 0.1 °C
Flue Gas Draught measurement 
Range ± 50 mbar
Accuracy ± 0.02 mbar
Resolution ± 0.001 mbar
Pressure measurement 
Range – 300 to 300 mbar
Accuracy ± 0.02 mbar
Resolution ± 0.001 mbar
CO/CO2 Ratio Calculation 
Range 0 to 99999
Resolution 0.0001
Efficiency (Net, gross, Condensing) calculations 
Range 0 to 120% ETA
Resolution 0.1 %
Air Ratio Calculation 
Range 1 to 9.99
Resolution 0.01
Excess Air Calculation 
Range 0 to 99.9 %
Resolution 0.1%
Heat losses Calculation 
Range 0 to 9.99 %
Resolution 0.1%
Conversions calculation 
emissions calculation ppm/o2% refer, mg/m3, mg/m3 with O2 reference
Pres-set fuels Nat Gas, Heavy Oil Light Oil, LPG, Propane, Butane, Kerosene,Coal, Diesel,Petrol,Coke, Anthracite, Wood@0%, Wood@10%, Wood@20%, Wood@30%, Wood@40%, Wood@50%, Pellets
Digital & Software
Communications micro USB, IRDA and Bluetooth as standard
Data logging 4000 Data log on internal memory  & SD card
Mobile APP ( Free) MRU4U working on IOS & Android
Software (Optional) WIN4U emissions software
Gas Sampling probe 250×8 mm  gas sampling probe with integrated temperature and draught measurement
Display 4 lines touchscreen graphic colour display
Weight 390 g
Dimensions 82x169x44 mm
IP protection IP 40
Power/main Li-ION rechargeable batteries, 2250 mA/h , USB charging AC 100-240 VAC, 46-63Hz, USB lead and wall charger supplied
Operating/Storage temperature 5 to 45 °C/ -20 to 50 °C
Warranty 5  years warranty when serviced annually by EIUK
Approvals Conform to BS 7967 , TUV SUD tested to BS EN 50279-1&2


  • Installation, commissioning and servicing of domestic and commercial Gas, Oil and Biomass boilers
  • Flue Gas measurement
  • Precise draught measurement
  • Efficiencies Calculations
  • Let-by & tightness test
  • CO ambient test
  • Differential temperatures


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RASI 300C Flue Gas Analyser