Gas Analyzer IRSD2/2

Alcohol analyzer for process automation.

Alcohol Fermentation Monitoring and Control

IR-SD2/2 Gas analyzer system for alcohol fermentations

Online detection of ethanol in the fermentation mash in real time without sampling and analysis.

2 SchematischeDarstellungIRSD
Mode of operation

The probe, a tube covered with a silicone diaphragm, is placed in the fermentation mash. Pressure adjusted instrument air is conducted through the probe and enriched with ethanol diffusing through the diaphragm.

For gas analysis an infrared (IR) sensor element is used which is located in the switchboard and connected with the ethanol enriched air stream. Depending on the transmitted signal, the corresponding ethanol concentration in the fermentation mash is calculated. Signal linearization is carried out by use of pre-installed calibration data.

The calculated ethanol concentration and tem­perature of the fermentation mash are indicated on the LCD display of the switchboard and, for the purpose of process control, converted to a standard current signal and two limit relay contacts which can be used as input signal for any process control system or for visualization and/or docu­mentation.

The standard design is made for simultaneous measuring in two parallel operating, independent fermenters (Probe I and Probe II in the drawing above). For specific applications also a single channel version can be provided.


The IR-SD2/2 gas analyzer system is applicable for any type of fermenter and any type of control system. It is easily installed and integrated with existing equipment.

The device consists of a probe which is placed inside the fermenting mash and connected to a switchboard by a flexible tube.

The switchboard is designed for field installation in the vicinity (less than 5 meter) between two fermenters, preferable on a wall to be free of vibrations. Power-supply and instrument air must be available, as well as connections to the PCS for further use of signal.

To mount the probe, a hole must be drilled into the fermenter shell.  It has to be placed in an area of the fermenter where the probe is permanently immersed in well-mixed mash.

A connection with a ball valve is welded into the hole, serving as mounting port for the probe. It can be inserted and also removed via the ball-valve while the fermenter is in operation. The fittings are included in the delivery.

Technical data


Weight of switchboard 10 kg   
Dimensions of switchboard (HxWxD) 400 x 400 x 200 mm
Power supply 230 V / 50 Hz
Instrument air supply (4 bar g) 20 Ndm³/h
Power consumption approx. 50W
Operating Range selectable, standard 0 - 15 vol% ethanol
Accuracy ± 0.2 vol% ethanol
Reproducibility ±0,05 vol% ethanol
Operating temperature range  0 - 45 °C
Output 4 - 20mA (analogue)
2 x relay contact (binary)


Process automation

Monitoring the ethanol formation in the mash is used to observe the progress in batch fermentations for optimization of the process efficiency.


This gas analyzer system was specifically developed by Vogelbusch for bioprocess applications.

It is made from standard industrial components to ensure optimum availability with minimum maintenance. The following design features are part of the scope of supply:

  • Local display of all process variables
  • Heat tracing to control condensation in the gas piping
  • Automatic temperature compensation
  • Detection of foam and liquid entrainment with emergency shut-off
  • Calibrated spare sensor
Sensor calibration

The instrument is delivered with pre-installed temperature compensation and the calibration function for alcohol/water mixtures in a range of 0 to 15 vol%, optional 0 to 5 vol%.

Recalibration to compensate raw material effects can easily be done by client on site.

In the event of sensor replacement, pre-calibrated sensors can be obtained from Vogelbusch or calibration can be carried out by client on site.

More details

Download brochure

» IR-SD2/2 Gas Analyser (pdf, 372 KB)


Similar developments are available from Vogelbusch for application in yeast and vinegar fermentations:

» GS2/7 Gas Analyzer for aerobic yeast fermentations

» GS2E Gas Analyzer for vinegar fermentations