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. Mass flow controllers feed gases to a collision cell (reaction cell) as part of an ICP-MS setup.

Our customers in this field indicated that for them a stable gas flow control with a compact flow instrument is essential. Besides that, they require a stable flow measurement and compatibility with the used gases in their process. We suggested a flow solution with the FLEXI-FLOW Compact instruments.

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Stable gas flow control for analytical equipment

Requirements analytical applications

A common factor in analytical applications is the need for a very low stable gas flow (in a range up to 1000 mln/min). Since the gas flow and its variations are directly visible in the measurement, the stability of the gas flow is important. Another aspect is the size of the flow instrument. As laboratory space becomes more and more expensive, the size of the instruments becomes something to consider. Small and compact flow instruments are on the wishlist of desktop instrument builders.

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 Compact 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 Compact 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 Compact 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 this mass flow controller is very compact, the response time is shorter then a few seconds.


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

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Flow controllers in analytical equipment

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