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Vega FIBERTRAC 31 Radiometric sensor

The FIBERTRAC 31 is a radiation-based sensor for continuous measurement of liquids and bulk solids with a flexible plastic sensing element. It is suitable for level measuring in situations involving key product features, aggressive products, or extremely high process temperatures. Even under the most demanding application circumstances, the FIBERTRAC 31 produces accurate measuring results.

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  • Benefits
  • Function
  • Technical Data
  • Materials/Scintillator
  • Housing versions
  • Electronics versions
  • Approvals
  • Adjustment
  • Electrical connection
  • Dimensions
  • High plant availability through non-contact measurement
  • Simple mounting on round and conical vessels thanks to flexible detector
  • Cost savings through use of only one sensor for measuring ranges up to 7 m

In radiometric measurement, a Caesium-137 or Cobalt-60 isotope emits focussed gamma rays. A special sensor on the opposite side of the vessel receives this radiation. The scintillator of the sensor converts these gamma rays into signals, the number of which is detected and evaluated. Since gamma rays are attenuated when penetrating matter, the sensor is able to calculate the level, the limit level, the density and the mass flow rate from the intensity of the received radiation.

Measuring range

1 … 7 m (3.28 … 22.97 ft)


±0.5 % at -20 °C … +50 °C

(-4 °F … +122 °F)

Ambient temperature

-20 °C … +50 °C (-4 °F … +122 °F)

Extended range available

Voltage supply

Operating voltage

20 … 72 V DC; 20 … 253 V AC, 50/60 Hz

Max. power consumption

4 W; 6 VA

Analogue input

Input type

4 … 20 mA passive

Internal load

250 Ω

Switching input

Input type

Ʋ Open Collector

10 mA

Ʋ Relay contact

100 mA

Relay output

Switching voltage

max. 253 V AC/DC

Switching current

max. 3 A AC (cos phi > 0.9), 1 A DC

Breaking capacity

min. 50 mW, max. 750 VA AC, 40 W DC

(with U < 40 V DC)

Current output


4 … 20 mA/HART, active or passive

Max. load

500 Ω (300 Ω with intrinsically safe IS)

Switching output

Type of output

NPN transistor output (floating)

Switching voltage

< 55 V DC

Load current

< 400 mA

General data


max. 9.2 kg (20.3 lbs) + 1.22 kg/m

(0.82 lbs/ft)

SIL qualification

Optionally up to SIL2

The detector rod consists of galvanized steel with a Santoprene rubber coating. Polystyrene is used as scintillation material.

The housing is available as double chamber version of Aluminium or stainless steel in protection class IP66/IP67.

The instruments are available in different electronics versions. Apart
from the four-wire electronics with 4 … 20 mA/HART, two purely digital versions with Profibus PA and Foundation Fieldbus are possible.

Worldwide approvals are available for VEGA instruments, e.g. for use in hazardous areas, on ships or in hygienic applications. The technical data in the respective safety instructions are valid for approved instruments (e.g. with Ex approval). In some cases, these data can differ from the data listed herein.

The adjustment of the instrument is carried out via the optional display and adjustment module PLICSCOM or via a PC with the adjustment software PACTware and corresponding DTM.
The Bluetooth version of display and adjustment module enables a
wireless connection to standard adjustment units. This can be for example a PC with PACTware and Bluetooth USB adapter.
Here, the adjustment is carried out via the adjustment software
PACTware and the respective DTM.

Two connection chambers are available. Depending on the instrument version, the signal output is either in the primary or in the secondary chamber.

Primary terminal connections

  • Voltagesupply
  • Relay output
  • Signal output 4 … 20 mA/HART active
  • Signal output 4 … 20 mA/HART passive
  • Signal input 4 … 20 mA
  • Switching input for NPN transistor
  • Switching input floating
  • Transistoroutput
  • Interface for sensor-sensor communication (MGC)
  • Setting the bus address for sensor-sensor communication (MGC)

Secondary terminal connections (intrinsically safe devices)

  • Terminals 4 … 20 mA/HART signal output
  • Contact pins for the display and adjustment module or interface adapter
  • Terminals for the external display and adjustment unit
  • Ground terminal

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