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GT812-1 Hydrogen Sulfide Gas Detector ( H2S Monitor )in 20, 50, 100, 200 or 1000 PPM

Product Literature

The Model GT812 has been replaced by Model GT814.

Features and Benefits

  • SST’s GT812 H2S gas sensor is the industry’s choice for its reliability, rugged design, and ease of use
  • Protects personnel from exposure from hydrogen sulfide gas
  • 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
  • Available in 20, 50, 100, 200 or 1000 PPM
  • Explosion-proof approved housing
  • Available up to IP66 rating
  • Uses Electrochemical Cell sensing element to accurately measure life threatening hydrogen sulfide 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
  • 5 Year Warranty
  • Made in the USA


Product Summary

GT812 Hydrogen Sulfide Gas Sensor monitors the presence of hydrogen sulfide gas in 20, 50, 100, 200 or 1000 PPM.  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. 5 Year Warranty.  Made in the USA.


Use the GT812-1 Hydrogen Sulfide 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 ELITE 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 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 ELITE LCD screen. There are no screwdriver or other manual adjustments required, and the calibration can be performed even in the presence of toxic gases.


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 minimum 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

Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 50 PPM

812-1-20 Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 20 PPM
812-1-50 Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 50 PPM
812-1-100 Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 100 PPM
812-1-200 Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 200 PPM
812-1-1000 Model GT812-1 NOVA-SensorElite™ Hydrogen Sulfide Gas Detector in 1000 PPM