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The Nova 481 Series CO analyzers utilize a simple and reliable microprocessor-based non-dispersive infrared detector specific to CO. The detector pulses an infrared beam of light through the sample tube, without the need for a mechanical chopper. In operation, the internal sample pump draws the sample gas through the filter/condensate trap, secondary filter, flowmeter, and then on to the infrared detector. The detector output is digitally linearized and then displayed as PPM CO on the digital meter. The output is also available as an analog or digital signal.

The Model 481L is a low range PPM version of the Model 481 analyzer.

Standard cabinet: NEMA 4 Weather-proof steel cabinet with window

Optional cabinets:
- NEMA 4X weather-proof & corrosion-resistant steel cabinet with window
- 19" rack mount
- NEMA 4 cabinet with Hazardous Area Purge System; available for Class 1 Div1 & Div2 hazardous areas

Unit of Measure


Method of Detection

N/A Single cell NDIR with no moving parts

Ranges Available

N/A 481L-0-500, 0-1000, 0-3000, 0-5000, PPM CO


N/A 0.1% CO on % versions, 1 PPM CO on PPM versions

Accuracy & Repeatability

N/A 1% of full scale


N/A Less than 2% of full scale per month

Response Time (T-90)

N/A Less than 15 seconds

Ambient Temperature Range

N/A 40 to 122°F (5 to 50°C), Lower temperatures (-5°C, -20°F) with Cold Weather Package


N/A ±1% of full scale

Size & Weight

N/A Physical data will vary depending on enclosure style and options required


N/A 115 VAC, 60 Hz 220 VAC, 50 Hz

Output Options

N/A 4-20 mA into 500 ohms non-isolated standard Isolated 4-20 mA, RS232, RS485, MODBUS, Ethernet outputs


N/A High and/or low alarm contacts available, relay contacts SPDT 5A @ 220 VAC rating Low flow alarm

Analyzer Type

N/A CO Analyzer



    For continuous analysis of carbon Monoxide (CO) in process gas streams using an infrared detector. Percent and PPM levels available as Models 481 and 481L respectively.



  • Percent or PPM levels CO by infrared
  • Detector is sensitive, very reliable, and non-depleting
  • Bright digital readout, 4 - 20 mA outputs
  • Fast response (T90 - less than 15 seconds)
  • Microprocessor control for push button calibration
  • Easy-to-maintain modular layout
  • Built in sample pump, flowmeter and filters



  • Hi/Low gas, low flow, and diagnostic alarms available
  • Isolated analog, RS232, RS485, MODBUS and Ethernet outputs available
  • Sample conditioning systems available for removal of moisture, acidic gas and dust
  • Cabinet purge system available for use in hazardous areas
  • One-step 'cal-now' button with touch screen LCD display
  • Full automatic calibration with touch screen LCD display
  • Cold weather package for operation to -20°C (-5 °F)
  • Cabinet coolers can be fitted to most models
  • Sensors mounted in temperature controlled heated box to improve accuracy.
  • High temperature filters and probes



  • Easily zero checked on ambient air
  • Span using a known CO in nitrogen (N2) calibration gas.

Unique Applications


    The 481 Series analyzers are designed for detection of CO in non-corrosive gas streams. All Nova analyzers are built using proven technologies and techniques. If this product does not suit your application, please contact Nova. In many cases, we are able to build an analyzer specific to your needs.

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