S421 flow

s420Stationary use

Due to the economic solution with S 421 flow the consumption measurement of compressed air and process gases in branch pipes becomes attractive. This allows the monitoring of gas consumption to different production units.

Mobile use

The compact design and easy use allows the measurement of compressed air / gas at machine level. In the picture beside S 421 flow is connected to the air supply of a machine.


Product Features

  • Easy and affordable installation
  • Units freely selectable via keypad m³/h, m³/min, l/min, l/s, kg/h, kg/min, kg/s, cfm
  • Compressed air counter up to 1,999,999,999 m³. Resettable to “zero” via keypad
  • Analogue output 4…20 mA, pulse output (galvanically separated)
  • High measuring accuracy also in the lower measuring range (ideal for leakage measurement)
  • Negligibly small loss of pressure
  • Thermal mass flow principle, no additional pressure and temperature measurement necessary
  • Gas types adjustable via software (N2, O2, CO2, N2O, Ar)


Technical data

Measured unit m³/h, m³/min, l/min, cfm, m/s, kg/min, kg/h, kg/s
(Reference standard can be programmed)
Default values:
* Air: Ps=1000 hPa, Ts=20 °C
all other gases: Ps=1013 hPa, Ts=0°C
Accuracy ± (2% of measured value + 0.3% full scale)
Temperature drift: 0.05 % / K
Pressure drift: 0.5 % / MPa
Stated accuracy at: Ambient/process temperature 23 °C ± 3°C
Ambient/process humidity < 90 %, no condensation
Process pressure at 0.6 MPa
Process connection: R thread(ISO 7-1),
Flange EN 1092-1, ANSI / B16.5, JIS B2220
Principle of measurement: Thermal mass flow
Sensor: Glass coated resistive sensor
Measuring Medium: Air, N2, O2, Ar, N2O, CO2
Operating temperature: -30 to 50 °C
-10 to 50 °C with local display
Operating pressure: up to 1.6 Mpa
up to 4.0 MPa (Optional)
Analogue output: Signal: 4 to 20 mA
Scaling: 0 to maximum volume flow
Accuracy: 0.06 mA
Pulse output: 1 pulse per consumption unit, insulated
switch output, max. 30 VDC, 20 mA
Power supply: 12-30 VDC, 2.4W
Display: 128 x 64 pixel, with backlight
Material: Measuring section:
Stainless steel 1.4404 (sus 316L)