Overlay and Sparge Gas Controller for Bioreactors.

The Model O2MIX gas mixer measures the oxygen and CO2 concentration in a gas sample inside instrument and uses this as feedback to control three (3) proportional valves to blend gasses from the three (3) inputs to a single output. The product uses feedback from actual gas measurements as a control point and different mixture and blends of gasses can be used to feed three (3) inputs for mixing. In normal operation the O2MIX is designed to accept Oxygen, Nitrogen (or Compressed “Air”) and CO2 as inputs, and a single blended output of a programmed mixture is produced by the unit to feed a Bioreactor.

  • Accurately mixes O2 and/or CO2 with air or nitrogen by measuring the gas concentration rather than by estimating mixtures from flow measurements.
  • Accurately controls flow independently.
  • O2 Range: 21 to 75%. Accuracy: + - 0.3% using tunable diode laser absorption.
  • CO2 Range: 0 to 10%. Accuracy: + - 0.2% using non-dispersive infrared.
  • Flow: 100 to 700 ml/min.

The O2MIX has internal pressure switches which provide ALARM control to warn the user if gas pressure is below operating levels and to warn of supply gas exhaustion. Measured oxygen concentration in percent volume fraction is displayed on a front panel alphanumeric VFD display. Two lines of 16 characters show numeric data and the parameter units or other annunciation. The instrument mode is controlled via a front panel keypad array. A back panel power jack and 9-pin RS232 connector provides the physical interface for power input, and serial link connections.

The model O2Mix has CPC O-Ring quick connect gas sample fittings and the inputs and output for easy connection and setup.

Unit of Measure

Performance Conditions

Ambient Temperature (Operating)

N/A 5 to 40 ºC40 to 102 ºF

Ambient Temperature (Storage)

N/A -20 to 60 ºC-2 to 140 ºF

Cell Pressure

N/A 10.2 to 17.4 psi70 to 120 kPascal500 to 900 mmHg

Warm-up for Full Accuracy

N/A 5 minutes


N/A Unit will operate up to 15,000 feet without re-calibration


N/A 0 to 95%, non-condensing

Performance Specifications


N/A 0 to 10% CO2 21 to 75% Oxygen


N/A 0.1% in 21 to 75% O2 range, 0.01% in 0 to 10% CO2 range


N/A 100 to 700 ml/min adjustable

Response Time

N/A Mixing gasses settle in several seconds

Stability (4 hrs)

N/A ±0.2%.CO2 after 5 minute warm up ±0.3%oxygen in XC mode, ±0.1% in oxygen LN mode

Electrical Specifications

Sensor Power Requirements

N/A 12VDC, 1.5 A

External Power Supply

N/A 95 to 250 VAC, 47 to 63 Hz

Mechanical Specifications

Dimensions (W x H x D)

N/A 7.5 x 3.0 x 14.0 in190 x 76 x 356 mm


N/A Instrument 7 lbs (3.2Kg) power Module 0.5 lbs (0.2Kg)