SIGNAL Instruments USA Microprocessor Control

Advanced Gas Analyzers

2-Year Warranty
Applications Gases Technologies
Series 4 Quasar
Quasar chemiluminescence detection (CLD) analyzers are recognized as the best practical analytical instruments for oxides of nitrogen (NOx) detection in a wide variety of applications.

The Signal Quasar series of Chemiluminescent NOx analyzers is unique in the market with a unique and very special ozone generator and extremely low levels of quenching effects from CO2 and H2O.

The "soft discharge" neon lamp ozone generator is unique among competitors, with its ability to use air as its feed gas without any unwanted generation of NO and NO2. (High voltage corona discharge techniques and UV lamps used by other manufacturers both suffer from this, and some well known manufacturers recommend the use of 100% Oxygen to avoid this effect, which becomes an high ongoing running cost to bear.) In contrast, our analyzers use air as an inexpensive and reliable source of oxygen for ozone.

The high vacuum and heated design also eliminates quenching, increases signal strength and also avoids any condensation in the sample and measurement which could cause losses of NO2 in condensate. The vacuum pump is of a dry piston design and is easy to maintain for continuous instrument use.

Also available is a non-vacuum model which is suitable for sample gas mixtures with low or consistent levels of CO2 and H2O, such as dilute Constant Volume Sampling (CVS) engine or vehicle exhaust measurement or off-road dry NOx testing (e.g. SORE).

We offer a single NOx detector, dual continuous NO, NO2, NOx detectors, non-vacuum for dilute and dry samples (e.g. CVS vehicle testing, off road dry NOx testing), and NOx, NH3, NO2 using selective converters and dual continuous detectors.

Quasar Features:

  • Dry, low maintenance pump
  • Electronic proportional band flow controllers
  • Long life NOx converter (5 years)
  • Special ozone generator uses air as feed gas
  • Very low quenching from CO2 and H2O

Series 4 Features:

  • 24Vdc or universal mains power supply
  • 2-year warranty
  • Contact closure outputs (user-configurable, 1A-rated) for health checks: 3 standard plus 20 additional (optional)
  • Fast speed of response
  • Free open source remote software
  • Full ethernet remote diagnostics and control
  • RS232 'AK' protocol, 4-20ma & 0-10vdc chart outputs
  • User configurable ranges plus auto-range per channel


  • Automotive exhaust emissions
  • Combustion analysis
  • Continuous Emissions Monitoring Systems (CEMS)
  • Environmental compliance
  • Gas purity
  • Gas turbine emissions
  • OEM system integration
  • Process monitoring
  • Research

Measurement technique(s):

Gas(es) measured:

  • NH3 (ammonia)
  • NO (nitric oxide)
  • NO2 (nitrogen dioxide)
  • NOx (oxides of nitrogen)
  • TN (total nitrogen)

Quasar Options:

  • Front panel screen = Required for onboard logging capability; supplied with a 2GB USB memory stick, but can also be used with flash memory SD card.
  • Highest full-scale measurement = 10%
  • Pump control module = for automatic remote control of pumps as part of system
  • Pump for sample - external = Used when sample is not under positive pressure.
  • Upgraded outputs = Adds 20 contact closure alarm outputs to (standard) 3 fitted to all units; outputs can be used for alarms or to control external functions (such as down-the-line calibration where valves to introduce calibration gas at the sample inlet point can be controlled automatically).
model detectors converters NH3 NO NO2 NOx TN
CLD-based analyzers for ambient measurement
CLD-ANO2 1 switched NOx converter x x x
Ambient pressure reaction chamber CLD-based analyzers
CLD-DNO2 2 NOx converter x x x
CLD-NO2 1 switched NOx converter x x x
CLD-NOx 1 switched NOx converter x x
Vacuum-CLD-based analyzers
HVCLD-DNO2 2 NOx converter x x x
HVCLD-DNOx 2 NOx converter x x
HVCLD-DTN 2 NH3 converter x x
HVCLD-NH3 1 switched NOx converter and NH3 converter x x x x x
HVCLD-NO2 1 switched converter x x x
HVCLD-NOx 1 switched NOx converter x x
HVCLD-TN 1 switched NH3 converter x x

Series 4 brochure (includes Quasar Technical Specifications)

We offer any combination of analyzers built into 19" rack sampling systems for your application. If your requirements are not in our standard product range, contact us about our customized system solutions.

Legacy Series III Model 4000VM remains available.

355 North York Rd.
Willow Grove, PA 19090
Tel: 215.830.8882
Fax: 215.830.8922
Toll free: 866.SIGNAL.U
Hours of operation:
M-F 8AM to 6PM Eastern Time
weekends and 24-hour emergency service by agreement
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