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Digital Control Systems

6475 SW Fallbrook Place Beaverton, OR 97008 USA

Toll Free: 1-877-468-6337

Phone: (503)246-8110

Fax: (503) 246-6747


AirSense Model 400

Model 400 Manual

M400 Brochure


  • True Dual-Beam Technology
  • Glass Frit-Sealed Optics
  • Long Term Stability
  • Digital Data Interface Available
  • Very Low Power Consumption
  • Set Point Relay Available
  • Flexible Sensor Configuration
  • Digital Display Available

The AirSense™ Model 400 Infrared CO2 Sensor is the first compact, general purpose OEM CO2 analyzer with state of the art dual-beam technology. This CO2 sensing technology was previously available only on the most expensive laboratory-grade instruments: the Model 400 now delivers the high-end performance of dual beam technology at an affordable price.

If the need for frequent calibration and the finicky nature of CO2 measurement equipment has been a problem for you in the past, the AirSense™ Model 400 CO2 gas analyzer is the solution.

Until now all but the most expensive laboratory grade IR CO2 analyzers used a single detector to measure the transmitted IR energy; the indicated concentration was directly proportional to the power level at the detector. Unfortunately the power of the detector changed not only with CO2 concentration, but many other factors as well. The 400 series’ completely digital, dual-beam IR CO2 detection system continuously measures and corrects for the short and long term changes that caused measurement errors in first-generation single-beam CO2 sensors.

The dual-beam 400 Series CO2 Sensor is the best choice for serious embedded carbon dioxide detection and/or control applications. Designed for the OEM market, this compact CO2 sensor requires less than 2 watts of operating power, provides linearized analog or digital measurement outputs, and is available in a wide range of mounting and sensing configurations. Many options (including adjustable set point control relay and digital display) are available for applications that need more functionality. Hermetically sealed optics, designed for use in continuously high humidity environments such as cell growth incubators, are standard.

The low power draw of the AirSense™ Model 400 makes it ideal for battery or other low power applications. Both voltage and 4 to 20mA current loop analog outputs are standard. The sensing cell can be configured for pumped sample draw or diffusion input. The sensing cell is normally attached directly to the main circuit assembly, but for those instances where the sensing cell needs to be remotely located, the sensing cell and main board can be tied together via a ribbon cable of a length specified by you.

The 400 Series CO2 sensor is the cost-effective way to incorporate the accuracy and stability of dual beam detection into all of your sensing and control applications.


Operating Principle

Dual beam, non-dispersive infrared (NDIR)

Detector Hermeticity

Sapphire window with glass frit seal

Sampling Method

Diffusion or pumped sample

Sensing Cell Proof Pressure
(sample cell only)

2 PSI (13.8KPa) gauge pressure

Measurement Range

0 - 20% CO2


± 0.1 % CO2


Less than 2.5% of reading / year


± 3% of reading or 0.1% CO2 at cal temperature

± 5% of reading or 0.1% CO2 over full operating temperature range

Warm up time

Less than 5 minutes

Operating Temperature

10 - 50° C 

Operating Humidity

Sensing Cell: 0 - 100% RH (non-condensing)
Electronics: 0 - 90% RH (non-condensing)

Storage Temperature

-20 - 60° C

Storage Humidity

0 - 90% RH (non condensing)

Analog Output

0 - 1 Volt
4 - 20mA (RLOOP less than 500 Ohm)

Digital Interface

Bi-directional i2c bus

Operating Power

7.5-15 VDC @ 170 mA max (125 mA AVG.).
Approx. 1.0W with 12 V. input

*With optional Sensor Module with Expansion Board (12-36 VDC 10-28 VAC)

Source Life

10 years minimum

Optional Relay Contact

Set point range: 0 - 20% in 0.1% steps
Hysteresis: 0.05% CO2 nominal
Contact Rating: 1A, 24VAC or VDC




Indoor Air Quality:
A guide for building owners and facility managers. Provides information about diagnosing indoor air quality problems. "Provides information about diagnosing indoor air quality problems."

IAQ for Schools:
Download a complete, practical plan to improve the air quality in schools.

Improve IAQ, While Saving Energy.
The use of CO2 sensors can save more than $1 per square foot of energy cost annually.