Application Note

Stable gas flow control for analytical instruments

Gas mass flow controllers are key components in many analytical techniques, like mass spectrometry, chromatography, atomic spectroscopy and combustion analysis. As an example: compact gas flow instruments are for feeding gases to a collision cell (reaction cell) as part of an ICP-MS setup.

The FLEXI-FLOW gas mass flow controller is a perfect fit for these processes, demanding stable gas flow control, compactness, short- and long-term stability and compatibility with used gases.

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Stable gas flow control for analytical equipment

Requirements analytical applications

A common factor in many analytical applications is the need for a very low stable gas flow (in the range of 1-1000 mln/min), Since the gas flow and its variations are directly visible in the measurement, flow stability is important. At the data sheet level, this requires good short-term repeatability and control stability, as well as good long-term stability over years of use. When gas flows are switched, the response time of the control at low flow becomes important, requiring small internal volumes in the gas supply system. As laboratory space becomes more and more expensive, the compactness of flow meters for desktop instruments is also something to consider.

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Important topics

  • Wide gas compatibility
  • Repeatable and long-term stable flow control
  • Fast switching of low gas flows 
  • Compact size

Process solution

Wide gas compatibility

The FLEXI-FLOW gas flow controller is an instrument that is applicable for a wide range of different gas types. And suitable for analytical desktop instruments that have a low gas flow rate, like 1-1000 mln/min of process gas and up to 20 ln/min of cooling gas (like Argon or Nitrogen).

Repeatable and long-term stable flow control

In analytical equipment, a carrier gas flow directly influences the measurement result. For example, the retention time of a substance in the column of a chromatograph directly depends on the stability of the flow. When the flow fluctuates, so does the measurement. The FLEXI-FLOW features short- and long-term control stability and gives the same performance today as one year later. 

Flow scheme

Fast switching of low gas flows

The FLEXI-FLOW can switch fast between different gases, which is an important feature for feeding gases to a collision cell, as part of an ICP-MS setup.
In these collision cells, unwanted compounds react with an additional gas in order to eliminate them. Switching of gases is then necessary. When measuring low flow rates, in the range of 1-10 mln/min, the switching time is related to the internal volume of the mass flow controller. As the FLEXI-FLOW is very compact, the response time is shorter then a few seconds.


The small size of the FLEXI-FLOW will make it a device of choice for compact benchtop analytical instruments.

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