Compress airThermal Mass Flow Meter CS VA 525 Cs Instrument

CS Instrument Thermal Mass Flow Meter

In-Line Air Flow Meter Model VA 525

Compact inline flow sensor with an integrated flow straightener

The newly developed VA 525 combines modern digital interfaces for connection to an energy monitoring system with a small, compact design. Due to its reasonable price and modern digital interfaces this compact in-line flow sensor is used when many machines (compressed air consumers) are to be integrated as easily as possible into an energy monitoring network.

The high-contrast, integrated display also displays the current values rotated by 180° if desired (very useful for overhead installation). Depending on the configuration, two of the following values can be displayed:

  • Current consumption in m³/h, l/min,
  • Total consumption (meter reading) in m³, l, kg
  • Temperature measurement
  • Optional: Pressure measurement

Intended use

The VA 525 consumption sensor is used for continuous flow measurements. The VA 525 consumption sensor is designed and constructed exclusively for the intended purpose described here and may only be used accordingly.

The user must check whether the instrument is suitable for the selected application. It must be ensured that the medium is compatible with the wetted parts. The technical data listed in the datasheet are binding. Improper handling or operation outside the technical specifications is not permitted. Claims of any
the kind based on improper use is excluded.


  • Compact, small design – for use in machines, behind maintenance unit at the end-user
  • Optionally with classic analog signals(4…20 mA and pulse) or digital interfaces such as Modbus RTU, Ethernet (also PoE), M-Bus
  • All interfaces are programmable via the display
  • Current consumption in m³/h, l/min,…
  • Total consumption (meter reading) in m³, l, kg
  • Temperature measurement
  • Optional: pressure measurement
  • Easy installation in existing piping through integrated measuring block (suitable for 1/4 ̋, 1/2“, 3/4 ̋, 1“, 1 ¼ ̋, 1 ½“ or 2″ lines)
  • Display values can be rotated 180° in the display, e. g. when installing overhead

Operating principle

The VA 525 consumption probe operates according to the calorimetric measuring method. The basis of this measuring method is the electrical heating of the mechanically protected built-in sensor. The mass flow, the volume flow, and the flow velocity can be measured and determined by the resulting heat flow to the passing medium (gas).

With the calorimetric measurement method (based on the measurement principle), the operating temperature and pressure of the medium have no influence on the measurement result, only the material data of the gas component are decisive.


Parameters m³/h, l/min (1000 mbar, 20 °C) in case of compressed air resp. Nm³/h, Nl/min (1013 mbar, 0°C) in case of gases
Units adjustable via keys at a display m³/h, m³/min, l/min, l/s, ft/min, cfm, m/s, kg/h, kg/min, g/s, lb/min, lb/h
Sensor Thermal mass flow sensor
Meas medium Air, gases
Gas types over CS Service Software or CS Datalogger adjustable Air, nitrogen, argon, CO2, oxygen
Accuracy (f. M. = from the measured value) (f. E. = from end value)
± 1,5 % of m. v. ± 0,3 % of f. s.
By request:
± 1 % of m. v. ± 0,3 % of f. s. or
± 6 % of m. v. ± 0,5 % of f. s.
Pressure measurement 0…16 bar, accuracy: 1%
Operating temp. -30…80 °C
Operating pressure Up to 16 bar
Digital output RS 485 interface (Modbus RTU), M-Bus (optional) Ethernet interface or PoE
Analog output 4…20 mA for m³/h resp. l/min
Pulse output 1 pulse per m³ or per liter galvanically isolated. Pulse value adjustable on the display. Alternatively, the pulse output can be used as an alarm relay.
Power supply 18…36 VDC, 5 W
Burden < 500 Ω
Housing Polycarbonate (IP 65)
Meas. section Aluminum
Mounting thread meas. section:
G 1/4“ to G 2“ (BSP British Standart piping) resp. 1/2“ to 2“ NPT-thread
Mounting position: Any

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