MASSFLOW – precise gas flow controller and measurement

MASSFLOW principle and advantages

LAMBDA MASSFLOW is a new mass flow controller system especially designed for use with MINIFOR laboratory bioreactors and fermentors. E.g.: it allows control of the pH of a cell culture by the controlled addition of gaseous CO2, the control of dissolved oxygen by regulation of the airflow or any other gas with a suitable controller. However, it can also be used independently, since all its functions can be controlled from the front panel of the MASSFLOW.

The measuring principle of thermal massflow measurement is particularly well suited for the measurement of gas flows. The key advantage of the measurement method is largely independent of pressure and temperature. Thus, in contrast to volumetric systems (e.g. rotameter), the pressure and temperature do not have to be measured.

The measuring system (mass flow sensor) consists of a heating element (H) and two temperature measurement points (temperature gauges T1 and T2). The gas flowing through the sensor draws off the heat from the heating element.

With MASSFLOW unit, a constant heating capacity ensures a flow-dependent temperature difference. When the gas flow is zero, the heating element (H) distributes the heat evenly so that the temperature difference
ΔT = T1 - T2, is zero.

The presence of a gas flow is accompanied by two effects which generate a temperature difference ΔT:

1) The temperature sensor (T1) located at the initial point of the channel measures a lower temperature, which is due to the cooling of the gas as it enters the chamber

2) The gas flowing over the heating element, transports heat to the temperature sensor (T2) located after the heating element, which results in an increased temperature T2. The hereby generated temperature difference ΔT is a direct measure of the mass flow of the corresponding gas

The high grade gas flow control allows also a high quality regulation of dissolved oxygen (DO) by air flow rate regulation and not just by variation of stirrer speed. We think that DO should be controlled at any stirrer speed! Or should one tolerate bad agitation at low DO values? The bad mixing could lead to accumulation of acid during pH control or generate other problems.

Types of MASSFLOW gas flow control and measurement unit

The flow rate is measured by high quality laminar mass flow sensor tubes and is displayed on a digital display. The mass flow cell has a very low-pressure drop (less than 1 cm of H2O) and a linearity error of less than ±3% reading (which is much better than the precision expressed as a percentage of full scale used by some manufacturers). The repeatability is better than ±0.5% reading. The flow rate is regulated by a specially developed proportional needle valve controlled by a microprocessor.

MASSFLOW, programmable
Gas flow measurement and regulation

Integrated with MINIFOR
MASSFLOW 0 – 5 L/min
0 – 5000 ml/min
0 – 500 ml/min
Air / O2 / N2Air / N2 / O2 or CO2 / Ar Air / N2 / O2 or CO2 / Ar / He / H2
Flow range: 0-5 l/min in 0.01 l/min steps (controller or meter) Flow range: 0-5 l/min in 0.01 l/min steps (controller or meter) Flow range: 0-500 ml/min in 1 ml/min steps (controller or meter)
Programmed directly on MINIFOR screen / Fnet, SIAM fermentation softwareProgrammable: 50 steps of flow, time & pauseProgrammable: 50 steps of flow, time & pause
Remote control through MINIFOR fermentorRemote control: 0 – 10 V; ON/OFF; RS-485 or RS-232Remote control: 0 – 10 V;     ON/OFF; RS-485 or RS-232

Gas flow measurement

0 – 5000 ml/min
0 – 500 ml/min
0 – 500 ml/min
Air / O2 / N2Air / O2 / N2Air / O2 / N2
or other gases
Flow range: 0-5 l/min in 0.01 l/min steps (meter only) Flow range: 0-500 ml/min in 1 ml/min steps (controller or meter) Flow range: 0-99.9 ml/min in 0.1 ml/min steps and 100-500 ml/min in 1 ml/min steps (meter only)

Meter only

Meter only

Meter only
RS-485 or RS-232 (optional); PC connection RS-485 or RS-232 (optional); PC connection RS-485 or RS-232 (optional); PC connection

Application of MASSFLOW gas flow meter and controller

LAMBDA MASSFLOW gas flow measurement and controller units can be used with MINIFOR fermentor and bioreactor and also as a stand-alone instrument. E.g.: MASSFLOW can be used to measure or regulate the gas flow in the laboratory; 4-gas mix for the existing bioreactor


MASSFLOW with proprietary precise and proportional needle valve integrated in the MINIFOR fermentor and bioreactor provides precise measurement and DO control by flow rate variation.

Measurement is independent of pressure, temperature or humidity variation during the fermentation process.

The automatic control the concentration of dissolved oxygen (DO) achieved by the flow rate variation and not merely by the variation in the stirring speed.


LAMBDA gas-mixing module allows a flexible thermal massflow controlled supply of different gases (air, O2, CO2, N2 or user defined gases) with individual gas flow paths for mammalian cell culture as well as microbial applications in the laboratory.


MASSFLOW gas flow controller can be used for the high cell density bacterial and yeast cultures under optimized fed-batch fermentation processes.