Hengesbach Keradiff 150 Differential Pressure Transmitter

The KERADIFF 150 has a robust, highly overload-resistant silicon sensor with an outstanding capacity for high
measuring accuracy, vacuum resistance and reliability for all long-term stable measurements. The high-performance
measuring system is used to measure differential pressure, filling levels and flow, in connection with differential pressure transmitters, for gases, vapours and liquids.

Medium- and process-suitable materials as well as different design variants allow the use of these devices with
corrosive or abrasive media, as well as for processes with high aseptic requirements (e.g. in the food or pharmaceutical industry). Flush-mounted versions and pressure transmitters for almost all process connections are available for filling level applications.

Various types of measuring cells for graded measuring ranges ranging from 10 mbar, PN 160 bar, to 40 bar, PN 420
bar, thus allowing for optimal adaptation to the process conditions. The digital communication signal (HART® protocol) can be superimposed onto the 4...20 mA signal and offers all information required for teleparametrisation (smart technology), as well as the version with the Profibus PA.


  • for measuring differential pressure, filling levels and flow
  • rapid use as a result of comfortable and simple operation
  • 4…20 ma, Hart® or Profibus output
  • measuring ranges from 1 mbar to 40 bar
  • high measuring accuracy < 0.1%
  • turndown 100 : 1
  • various process connections


Device typeKERADIFF 
ApplicationDifferential pressure measurement
Measuring sensorSilicon sensor 


Output signal4…20 mA with superimposed HART® protocol or PROFIBUS PA
Breakdown signal3.6 mA minimum alarm, 21 mA maximum alarm
Current limit3.8 mA; 20.5 mA
ResolutionCurrent output: 1µA
 Display: adjustable

Measuring accuracy

Influence of the system pressure on the zero point and range0.2% / 100bar 
Thermal change± 0.2% for -40..-10°C or +60…+85°C
Temperature coefficient for zero signal or output range0.02% / 10K (-10…+60 °C) and
 0.1% / 10K (-40…-10 °C or +60…85°C)
Temperature coefficient of the pressure transmittersee pressure transmitter table for TK of the zero point
Deviation from the characteristic curve:max. 0.1% 
 max. 0.2% for the measuring limit range
Hysteresis:0.1% of the set range
Repeatability:0.1% of the set range
Heating time:4…20 mA HART® < 10s, PROFIBUS PA 6s
Setting time:between 0.5 and 2s, depending on the measuring range
Rise:between 0.4 - 1.6s, depending on the measuring range
Long-term drift0.2% / a 
Adjustable attenuation0…999s, adjustable via on-site operating field or PC (factory setting: 2s)

Conditions for use

Medium temperature-40…+85 °C 
Nominal temperature-40…+85 °C 
Operating temperature-40…+85 °C 
 -20…+70 °C with on-site display
Storage temperature-40…+100 °C 
 -40…+85 °C on-site display
Protective class according to EN 60529IP 67 
Electromagnetic compatibility (EMV)Electromagnetic compatibility according to EN 61326 and NAMUR recommendation EMV
Vibration strength± 0.1% according to DIN/IEC 68, Part 2-6, based on sensor range, measured on a 6000
 mbar sensor 
Installation positionAny, compensation when calibrating the measuring start

Auxiliary energy

Supply voltage11.5…45V 
Residual rippleNo influence for 4…20 mA signal up to ± 5% residual ripple
Design configuration  
MaterialsHousing:Copper-free die-cast aluminium housing with a protective coating on a
  polyester basis, grey, resistant to seawater, salt-spray test DIN 50 021 (504
  hours) passed, optional process connection, O-rings made from NBR for
  cover sealing, assembly bracket made from C22.8
 Membrane:AISI 316 L
 Flange:DIN 19213 from AISI 316 L
 For KERADIFF 140, 150:
 Pressure transmitter from AISI 316 L, see corresponding data sheets, special materials
 Capillary tube and holding pipe made of AISI 316 L
 KERADIFF 150: Installation of the pressure transmitter: rigid connection via holding flange
  (see diagram) or via a capillary tube (max. 8 m), to be specified if
Process connectionsAll standard and common connections (see dimensional drawings)
Electrical connectionM20x1,5 
 Terminal connection with built-in inter-clock diode for cable diameters of 0.5 to 2.5 mm²,
 two-wire connection cable with a standard installation cable.
Climate classClass 4K4H (air temperature: -20…+55°C, relative humidity: 4…100%) according to DIN
 EN 60721-3-4 fulfilled (condensation possible)

Download Data Sheet: Hengesbach Keradiff 150 Differential Pressure Transmitter

Ref: hengesbach.com