Pressure

Technologies

Piezoresistive measuring cells

Piezoresistive measuring cell

The functional principle of the piezoresitive cell is based on a silicon chip provided witha pressure-sensitive diaphragm. This diaphragm includes the resistors oft he measuring bridge. The sensitive siliconchip and the process medium are isolated by a stainless steel diaphragm. A silicone fluid is used for the internal pressure transmission.

Advantages:

  • low pressure ranges are possible
  • high output signal (> 100 mV)
  • high overload protection

Ceramic measuring cells

Ceramic measuring cell

On the basis of a ceramic measuring cell body, resistors are printed onto the diaphragm (thick-film technology). Like in thin-film cells, in ceramic cells the measuring diaphragm also acts asan isolation diaphragm to the medium. An internal transmitting fluid is not required.

Advantages:

  • higher signal deviation than thin-film strain gauge
  • integrated temperature compensation
  • higher corrosion resistance than stainless steel
  • chemical diaphragm seals not required

Hall Effect

Graphic Hall Effect

If a magnetic field acts onto an electric conductor perpendicular to the current direction, the electrons will be deflected by the Lorenz force. The electron displacement caused by this effect can be measured as Hall voltage. The Hall effect is used to determine the deflection of elastic measuring elements. For this purpose, the magnet is fixed to a diaphragm or a measuring spring. In the Hall sensor, the pressure-proportional signal is converted into a switch signal. The switching point is set by displacing the sensor through an adjustment screw.

Advantages:

  • no connection between measuring element and electronic system
  • integrated temperature compensation
  • small measuring ranges
  • low failure probability
  • medium resistance at low costs for the measuring element