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The Nova 501 Series Multi-gas Ambient Air Alarm analyzers are designed for the continuous monitoring and alarm of up to four gases in any combination including: O2 deficiency, CO2, SO2, NO, NO2, H2, CO, CL2, NH3, H2S, % RH, and temperature of ambient air.
A built in pump draws in the sample for analysis. A 1/4" plastic tube may be attached to the analyzer to sample a different area, if desired. Alarms are provided for all gases. An audible 'Sonalert' will sound if any reading goes into alarm and an indicator light beside each digital meter shows which gas is in alarm. A reset button is provided to silence the alert.
Unit of Measure


Method of Detection

N/A O2, CO, SO2, NO, NO2, H2, CL2, NH3 and H2S by electrochemical sensor, % RH by dielectric ceramic sensor, CO2 by infrared sensor

Ranges Available

N/A 0-100 PPM NO 0-100% RH 0-20 PPM H2S 0-20 PPM NH3 0-20.0 PPM CL2 0-20.0 PPM NO2 0-200 PPM CO 0-200 PPM H2 0-25.0% O2 0-50°C Temp. 0-50.0 PPM SO2 0-5000 PPM CO2


N/A 0.1% on % gas, 1 PPM on PPM gas

Accuracy & Repeatability

N/A ±2% of full scale


N/A 2% per month

Response Time (T-90)

N/A Varies with individual sensor but generally under 2 minutes for full reading

Ambient Temperature Range

N/A 4 to 40 ºC40 to 105 ºF


N/A ±2% of full scale or 1 PPM, whichever is greater

Size & Weight

N/A Dimensions and weight will vary based on the number of gases and sample conditioning system


N/A 115 VAC, 60 Hz for recharging 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


N/A One low O2 alarm and one high alarm for all other gases. Separate relay contacts for each gas with 5A rating. Separate indicator lights. Common 'Sonalert' audible alarm with reset button. Field-adjustable set points.

Gases Measured

N/A 0) NH3 - 0-20 PPM 1) O2 - 0-25.0% 2) CO - 0-200 PPM 3) CO2 - 0-5000 PPM 4) LEL Combustibles (not avail. for 5287 Series) 5) H2S - 0-20 PPM 6) SO2 - 0-50 PPM 7) NO - 0-100 PPM 8) NO2 - 0-20 PPM 9) CL2 - 0-20 PPM



    For simultaneous analysis and alarm of up to four of any combination of O2 deficiency, CO2, SO2, NO, NO2, H2, CO, CL2, NH3, H2S, % RH, and temperature of ambient air.



  • All gas detectors contained in one NEMA 12 wall mounted enclosure
  • Microprocessor controlled sensors
  • Separate sensor for each gas
  • Bright digital readout for each gas
  • Built in sampling pump
  • Easy to maintain modular layout
  • Single alarm points for each gas with individual alarm lights and common 'sonalert' audible alarm
  • Audible alarm reset button provided
  • Alarm contact for each gas
  • Recorder output of 4-20mA or voltage for all gases



  • Isolated analog RS-232, RS-485, MODBUS, or ethernet outputs available
  • Strobe light
  • RS-485 output
  • Automatic calibration with touch screen display
  • Low sample flow alarm
  • Multiple alarm points for measured gases
  • Multipoint sampling using Nova 402AS



  • Ambient air for O2 and to zero all other gases
  • Analyzed calibration gas with representative concentrations for span of all other gases

  • Unique Applications


      Warm up time is approximately two minutes however NO and NH3 may take up to 2 hours for full stability. The operating humidity range for this series of analyzers is 0-90% RH non-condensing. 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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