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KJLC® 925 Series Pirani Gauges & PDR900 Controller

Note For a direct replacement, please see the new 925 MicroPirani Gauge or consider the 375/275 combo as a possible alternative. Please contact gauging@lesker.com for further details or technical support.

These transducers are thermal conductivity gauges based on a unique, MEMS-based sensor.

  • Commonly used for vacuum pressure measurement applications in semiconductor and analytical environments, as well as general vacuum applications
  • Wide measurement range from 1 x 10-5 Torr (mbar) to atmosphere —based on measurement of thermal conductivity in a small cavity where gas enters by diffusion only, instead of flow

Our transducers experience significantly less problems with temperature drift, low accuracy, calibration, and sensitivity to mounting position compared to traditional Pirani gauges.


  • Increased pressure measurement range from 10-5 Torr (mbar) to atmosphere, two decades beyond a standard Pirani
  • Set-point relay features a fast response time for reliable process control
  • Compact dimensional design
  • High accuracy and reduced process cycle time
  • Ease of operation via analog output and digital communication
  • CE marked, compliant with EMC Directive 89/336/EEC


  • One-millimeter square silicon chip enables measurements to be made in a very small volume
  • Small size and repeatable geometry gives it a range from atmosphere down to 10-5 Torr (mbar)
  • Design minimizes the effects of convection—operation is possible in any position without compromising accuracy, simplifying installation
  • Solid-state design is highly resistant to air inrush, vibrations, and mechanical force, resulting in less system downtime due to broken filaments


  • Zero adjust
  • Atmospheric adjust
  • Gas type selection
  • Pressure unit selection
  • Baud rate and addressing
  • Factory default
  • Set-point functions

Specifications Table

Measurement MethodPirani
Measurement Range1.0 x 10-5 Torr (2.7 x 10-5 mbar) to Atmosphere
Communications InterfaceDigital RS-485 or RS-232
Power Requirements10-30 VDC, <1.5 W
Accuracy (% of measurement)10-4 to 10-3 Torr (mbar): 10% of reading 10-3 to 100 Torr (10-3 to 133 mbar): 5% of reading 100 Torr (133 mbar) to Atmosphere: 25% of reading
Temperature (operating)0-40° C
Temperature (bakeout)85° C for Shielded model (gauge tube only)
Materials Exposed to VacuumSiO, SiO2, SiN4, gold, epoxy resin,
304 stainless steel, Kovar®, Viton®
Repeatability (Typical)10-4 to 10-3 Torr: 8% of reading 10-3 to 100 Torr: 2% of reading 100 Torr to Atmosphere: 10% of reading
Set-Point Range2.0 x 10-3 to 990 Torr (2.67 x 10-3 to 1,320 mbar)
Set-Point Relays1 SPDT @ 1A (resistive)
Relay Response50ms (maximum)
Mounting/Installation OrientationAny
Calibration GasAir, argon, helium, nitrogen, hydrogen, water vapor
Analog Outputs1-9 VDC (1 volt per Decade)

Product Manual
For a download of the product manual, click here.
Contact Us
To speak with someone directly, please call +1 412 387 9200 or email international@lesker.com.