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GT812 NOVA-Sensor Elite™ Toxic Gas Detector

Product Literature

The Model GT812 has been replaced by Model GT814.

Features and Benefits

  • SST’s GT812 toxic gas sensor is the industry’s choice for its reliability, rugged design, and ease of use
  • Toxic gas sensor models available:  H2S Detectors, Ammonia Detectors, Chlorine Detectors, and others
  • Protects personnel from exposure from toxic gases such as H2S, Ammonia, and others
  • A self-contained and stand-alone device
  • Provides 4-20 mA ouput signal
  • Voltage-free relay contacts
  • Bright LCD with continuous display of gas concentration in PPM
  • Explosion-proof approved housing
  • Available up to IP66 rating
  • 5 Year Warranty
  • Made in the USA
  • This highly versatile model from SST can be ordered with various sensors to specifically detect hydrogen sulfide or H2S, ammonia or NH3, chlorine or CL2, and other harmful and toxic gases
  • Uses Electrochemical Cell sensing element to accurately measure lifethreatening toxic gases
  • Shipped fully assembled and precalibrated. Installed and fully operational in less than 1 hour
  • 4-20 mA output for connection to external equipment, including SST NOVA-5000 Modules, PLC’s, SCADA or distributed control systems
  • Two alarm set points with voltage-free contact outputs for local control
  • Pushbutton switch initiates test or calibration sequence (no magnet required)
  • On-screen calibration instructions insure error-free results
  • Available for these gases:  Hydrogen Sulfide (H2S), Ammonia (NH3), Sulfur Dioxide (SO2), Carbon Monoxide (CO), Chlorine (CL2), Hydrogen Fluoride (HF), Hydrogen Chloride (HCL), Propolene Oxide (OCH2CHCH3) Nitric Oxide (NO), Nitrogen Dioxide (NO2), and Ethylene Oxide (C2H4O)


Product Summary

GT812 NOVA-Sensor Elite™ Toxic Gas Sensor is our latest intelligent model toxic gas detector which monitors the presence of toxic gases such as H2S or hydrogen sulfide, ammonia, carbon monoxide, chlorine, and other toxic gases.  Self-contained device, measures and displays the concentration of gas accumulated in a protected area, performs local control functions, and optionally transmits this information to a central control point.  Features a bright LCD display of gas, 4-20 mA output signal, dry contact relays, and on-screen calibration instructions.  5 Year Warranty.  Made in the USA.


Use the NOVA-Sensor Toxic Gas Detector to alert personnel when life-threatening gas is present in a protected area. This detector uses an electrochemical fuel cell sensing element, and provides accurate measurements in all atmospheres. A high reserve of electrochemical activity insures a long life and excellent temperature stability. The performance is relatively unaffected by humidity, providing that conditions are noncondensing,

The display screen on the NOVA-Sensor continuously displays operating status and the actual concentration of toxic gas in parts per million (PPM). This reading is converted to a standard 4-20 mA signal, which may be connected to any remote device for remote display or logging. Relay contacts are provided which transfer when the gas SAFETY SYSTEMS TECHNOLOGY novagas toxic concentration exceeds the LOW ALARM and HIGH ALARM set points. Typical set points are adjusted by the installer upon installation and may be reset later by authorized personnel. The relays are suitable for controlling local HVAC equipment, alarm signal devices or for equipment shutdown. Fault relay contacts are also available which operate upon loss of power or internal failure of the unit.

The automatic calibration sequence is initiated by depressing the pushbutton switch located on the side of the enclosure. During calibration, step-by-step instructions are displayed on the NOVA-Sensor screen. There are no screwdriver or other manual adjustments required, and the calibration can be performed even in the presence of toxic gases.

Model GT812 NOVA-Sensor Elite™ Toxic Gas Detector
Typical toxic gases for pre-calibrated NOVA-Sensor Toxic Gas Detectors include

H2S – Hydrogen Sulfide Detector
SO2 – Sulfur Dioxide Detector
CO – Carbon Monoxide Detector
NH3 – Ammonia Detector
CL2 – Chlorine Detector
HF – Hydrogen Fluoride Detector
HCL – Hydrogen Chloride Detector
OCH2CHCH3 – Propolene Oxide Detector
NO – Nitric Oxide Detector
NO2 – Nitrogen Dioxide Detector
C2H4O – Ethylene Oxide (ETO) Detector

Technical Specifications and Ordering Information

Technical Specifications

Power Input: 24 volts DC nominal, 80 mA standby, 140 mA alarm Will operate within specifications at any supply voltage between 16 and 32 volts. Operating Temperature: -22 to +122°F (-30 to +50°C) H2S -4 to +122°F (-20 to +50°C) SO2 -4 to +131°F (-20 to +55°C) CO -13 to +131°F (-25 to +55°C) NH3 -4 to +122°F (-20 to +50°C) CL2 All sensors may be operated intermittently up to +150° F. Relative Humidity: 15% to 90% non-condensing May be operated intermittently from 0 to 99% RH Ingress Protection: IP40 to IP66 Depends on installed protection options
Zero Drift: Less than ±0.1 PPM pre month
Sensitivity Drift: Less than 2% change per month
T90 Response Time: Less than 20 seconds
Accuracy: Linear response 0 to 20 PPM PPM error at full scale ±6 PPM.
Operating Life: 24 months monimum Plug-in replacement of electrochemical cell recommended every 24 months
Relay Outputs: Low Alarm (latching or nonlatching) High Alarm (latching) Malfunction (non-latching)
Relay Contact Ratings: 6 amps @ 28 VDC or 300 VAC resistive 1/8 HP @ 120/240 VAC
Analog Output: 0 to 20 mA into a load of 600 ohms or less
Size: 7 x 9 inches, 4.75 inches deep (178 x 229 x 121 mm) Includes junction box and sensor. Conduit connection is ¾ inch NPT thread.
Weight: 6.25 pounds (2.83 kg)

Ordering Information