Pura Transmitter

For measurement of trace moisture content in high purity gases

The Pura transmitter is a simple, economical and very effective solution for on-line measurement of dew point temperatures down to -120°C (equivalent to less than 1 part per billion).

The transmitter is suitable for large-scale integration into a semiconductor fabrication plant or high purity gas line, where residual moisture content of the gas is critical to satisfactory operation of a process.

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  • Range: -120 to -40ºC dew point
  • Accuracy: ±1 to ±4 (range dependent)
  • Flow Rate: 1 to 5 Nlmin-¹
  • Operating Temperature: -40 to +60°C
  • Operating Pressure: Minimum 10-7 Pa , Maximum 24MPa
  • Power Supply: 24V dc
  • Output: 4-20 mA & RS485
  • Pressure Rating: 10-9 torr to 24 MPa
  • Pure Gases
  • Semiconductor manufacture
  • Fiber optic production
  • Electronic component manufacture
  • Optical coating processes
  • Industrial Gas production and distribution

The Pura uses Impedance technology.

The operation of this sensor depends on the dielectric property of water molecules absorbing onto an active porous insulating layer sandwiched between two layers of conductive material deposited on a ceramic substrate. Water has a very high dielectric compared to the dielectric of the active layer and the background of the carrier gas so it can be detected easily. 

The active layer is very thin – less than one micron and the porous top conductor that allows water molecules to penetrate into the active layer is less than 0.1 micron thick. This allows the sensor to respond very rapidly to changes in the moisture surrounding it both when moisture decreases (drying) and increases in the sensor environment.