7866 Thermal Conductivity Analyzer

7866 Thermal Conductivity Analyzer


Honeywell's 7866 Thermal Conductivity Analyzer is designed to provide a highly sensitive and accurate analysis of a binary (two-component) mixture of gases. The analyzer can also be calibrated to measure a single component of a multi-component gas mixture, providing the background gases that constitute a stable mixture (such as air) or have approximately the same thermal conductivity.

The 7866 Analyzer uses the principles of thermal conductivity to determine the concentration of a sample gas through the measurement of thermal losses from two highly stable, matched thermistor probes inserted in a stainless steel block.

The 7866 Analyzer consists of three basic components: the sensing unit (transmitter), the control unit (receiver) and a power supply. The sensing unit receives a continuous flow of the binary or multi-component gas mixture, measures the concentration of the sample gas and transmits an electrical signal to the control unit. The sensing unit is ruggedly constructed to meet most environmental conditions and is designed to be mounted up to 1,000 feet from the control unit with only a single multi-conductor non-shielded cable connecting the two, resulting in greater flexibility and lower installation costs.

The control unit receives the output signal from the sensing unit at the sampling site by way of the interconnecting cable. The control unit is designed for simplified panel mounting either at the sampling site, if environmental conditions permit, or in a control room. The unit provides a current output signal to a remote device for monitoring or recording purposes. The control unit is supplied with one or two alarms. When an alarm is detected, the specific relay de-energizes, creating an open circuit that can activate an external annunciator or a relay to initiate a shutdown procedure for the process. When power is off the alarm relay is de-energized and the normally open contact is non-conducting (open).

Two versions are available - a Triple Range Analyzer for hydrogen-cooled generator applications in the power industry and Single Range Analyzer for gas measurement in a variety of applications and industries.

Triple Range Analyzers provide accurate monitoring of hydrogen purity (detection of air leaks during operation) in hydrogen-cooled generators. The Triple Range Analyzer also monitors carbon dioxide in air and carbon dioxide in hydrogen ensuring safe execution of the purge cycles.

An optional prepackaged Model 7872 Sample Panel provides a complete pre-engineered panel designed specifically for hydrogen-cooled generator applications in utility, paper mills and other co-generation applications. The sampling system allows easy, convenient calibration of all three ranges.









  • Easy to use prompts
  • Security code protected
  • Reliable solid state design
  • High speed of response
  • High sensitivity
  • Excellent stability
  • Low maintenance requirement
  • Low installation costs through optional remote mounting capability of the sensing unit (transmitter)
  • Explosion-proof housing on the sensing unit available
  • Signal transmission from the sensing unit up to 1,000 feet over unshielded lead wires
  • Panel-mounted 1/4 DIN control unit (receiver) with easy-to-read display
  • Current output signal from the control unit representing measured PV
  • Single or dual alarms
  • Triple Range Analyzer for hydrogen-cooled generator applications is available
  • Triple Range Analyzer has a second current output used to retransmit ranging data to optional indicator model (mutually exclusive with Alarm 2)
  • Optional Modbus communications supports configuration and data acquisition



7866 Gas Analyzer Datasheet