Measuring systems for compressed air and gases

From the supply line of a process to the process itself, there are many places where leaks can form. Consumption measurement is important because there is an enormous potential for savings in the event of leakage, especially with compressed air (argon, nitrogen and oxygen are much more expensive). A sample calculation is given below to illustrate this:

A medium-sized production company is given.

Typical compressor performance

16 m³/min = 960 m³/h

Utilization rate

80% incl. night idle

Electrical connected load


Annual operating time

8760 hours

Energy costs

8760 h x 80 kW x €0.15 = €105,120 per year

Leak Rate

Approx. 20 - 30% of the total consumption (typical for old systems)

Potential savings

Approx. €26,280 per year from leaks alone


In order to enable an accurate measurement of a flow rate, there must be a laminar flow, because this is the only way to reliably calibrate. Depending on factors such as the density, viscosity, pipe diameter and velocity of the air, either laminar or turbulent flow can occur.

durchfluss engl

Measure flow

Thermal mass flow
This thermal measurement method uses a sensor with two platinum resistors. R1 measures the gas temperature as a reference to R2, which is heated to a constant, previously determined temperature (e.g. 10° C above the value that R1 delivers).
The higher the power, around R2 at constant temperature hold, the higher the mass flow that flows through.
This process is ideal for dry and processed compressed air, technical gases and mixed gases.

Differential pressure principle
An integrated differential pressure sensor measures the dynamic pressure at the sensor tip. The dynamic pressure depends on the speed of the medium in the pipe. The flow rate can be determined by the pipe diameter.
The differential pressure method is used in hot and wet conditions. The sensor can be attached directly to the outlet of the compressor. It also offers fad measurement. This process is intended for top speeds of up to 600 Nm/s. Measurements of fast processes are possible up to a speed of 100 ms.

differenzdruck engl

  • RS 485 interface, Modbus-RTU as a standard
  • Integrated display for m³/h and m³
  • Usable from 1/2“ to 12“ (DN 300)
  • Easy installation under pressure
  • 4...20 mA analogue output for m³/h resp. m³/min
  • Pulse output for m³
  • Inner diameter adjustable via keypad
  • Consumption counter resettable
  • Adjustable via keys at the display: Gas type, reference conditions, °C and mbar, 4...20 mA scaling, pulse weight
User Manual

  • The integrated Modbus interface enables the connection to superordinated control systems like energy management systems, building management systems, SPS, SCADA,
  • Easy and affordable installation
  • Units freely selectable via keys at the display 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. Resetable 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
  • Calorimetric measuring principle, no additional pressure and temperature measurement necessary, no mechanically moved parts
  • Comprehensive diagnosis functions can be read out at the display or by remote access via Modbus-RTU like e. g. exceeding Max./Min values °C, calibration cycle, error codes, serial number. All parameters can be read out and changed via Modbus

  • Robust impact-proof aluminum die cast housing for the outdoor area IP 67
  • All medium-touching parts made from stainless steel 1,4571
  • As immersion sensor suitable for 3/4“ up to DN 500
  • On request with ATEX approval ATEX II 2G Ex d IIC T4
  • On request with DVGW approval for natural gas (up to 16 bar)
  • Pressure range up to 50 bar, special version up to 100 bar
  • Temperature range up to 180 °C
  • No moving parts, no wearout
  • Sensor tip very robust, easy to clean
  • Easy mounting and dismounting under pressure via 1/2“ ball valve
  • Housing twistable, display twistable by 180°
  • Safety ring for mounting and dismounting under pressure
  • Depth scale for precise installation

Flow meter VA 570 is supplied with an integrated measuring section for compressed air and gas pipes. The measuring sections are available in flanged version or with R resp. NPT thread.

User Manual
User Manual
User Manual

Flow meter VA 570 is supplied with an integrated measuring section for compressed air and gas pipes. The measuring sections are available in flanged version or with R resp. NPT thread.

User Manual
User Manual
User Manual

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