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S421 Flow and Consumption Meter for Compressed Air and Gases (in-line sensor)

With a wide measuring range, a high resolution and a sampling rate, the S421 provides very fast and precise measurement.


The S421 compressed air flow and consumption meter covers a wide measuring range.

With the high resolution and sampling rate, a very fast and precise measurement is achieved. The installation is done through the selected measuring section, with an R-thread or with a flange connection. The sensor is able to save two calibration curves, due to this the sensor can be used in two different gases without any loss of accuracy, for example, the compressed air flow can be measured but a the same time it can be used in Nitrogen. The optional colour display is designed to show all measured values like flow and total consumption.

At the same time, the display can be used to manage the sensor settings like pipe diameter, gas type or analogue output scaling. The sensor offers two different signal output options. It can have an isolated analogue and pulse output to read out the flow and the total consumption. Alternatively, a MODBUS RTU interface can be used to access all measured values via the digital interface.

Various settings such as gas type, flow unit, and reference standards, can be set ex-factory according to your needs. If it’s needed to change the settings on-site, then you can use our free S4C-FS mobile phone application for android phones. This enables you to change the settings wirelessly on-site, within a touch of your smartphone. Managing your compressed air was never easier.

The S421 is the perfect meter to monitor your compressed air system and measure the compressed air flow and consumption.


  • Easy and affordable sensor solution to measure the compressed air flow and consumption
  • The sensor is calibrated in the measuring section, this allows a very high precision
  • Two calibration curves can be saved onto the sensors internal memory
  • Due to the two calibration curves, the sensor can be used with the highest precision in two different gases
  • Velocity, Flowrate, Consumption and Temperature are displayed
  • IP65 protection class offers rugged protection in a rough industrial environment
  • Isolated analogue and pulse outputs or MODBUS/RTU interface
  • Thermal mass flow measurement, pressure and temperature independent
  • Very fast response time, high precision and wide measuring range
  • Pipes sizes available: DN15, DN20, DN32, DN40, DN50, DN65,DN80
  • Integrates seamlessly in your compressed air system
  • Fits your needs: various process connections available(R-thread, EN 1092-1 flange or ANSI flange)
  • Exchangeable sensor unit (easy sensor swap)
  • Optional flow conditioner, no need for a straight inlet anymore
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