The GDA 40125 Gas Detection Controller is a standalone gas detector unit with inbuilt display, sounder, flasher, relays and alarm driver. Available in the full range of GDA 2500 series electrochemical sensors which are temperature compensated and easily replaceable.

Designed, manufactured and supported locally in Australia.

The GDA 40125 has 2 user relays which can be programed to operate at any level within the gas detectors operational range as well as an independent fail safe fault relay. The unit's alarm state is indicated by the display and by flashing LEDs additionally there is an o/p to drive a 24 VDC sounder / flasher (AVR-20) all of which can be muted from the front panel.

  • Available for Carbon Monoxide, Oxygen, Ammonia, Hydrogen Sulphide, Sulphur dioxide and other gases on request
  • 24 VDC operation with optional plug mounted power supply
  • 4-20 mA o/p and optionally Modbus o/p
  • Backlit LED display
  • Real time display of gas concentration
  • Mutable internal sounder
  • 2 User selectable/ configurable alarm relays (SPCO)
    • Alarm relays are inhibited during calibration.
  • External Mutable drive for AVR-20 series sounder / flasher unit.
  • 1 Fault relay (SPCO)
  • Australian Factory Certificate of Calibration

Poisoning: GDA sensors are designed to operate in a wide range of harsh environments and conditions. However, it is important that exposure to high concentrations of solvent vapours is avoided, both during storage and operation.

Made in Australia and Supported in Australia

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Designed, Manufactured and Supported in Australia.

Car Park Gas Monitoring Systems

The Gas Detection Australia car park gas detection system comprises of 1 up to 16 GDA 2525 carbon monoxide car park gas detectors per zone or level. The car park gas concentration signals are sent from the car park gas detector and the highest level from all the car park gas detectors are displayed locally on the control unit.  The latest regulations (AS1668.2-2012) call for variable extraction control and minimum flow rates. Gas Detection Australia car park system's allows variable-speed drive (VSD) control  that will meet this requirement of the australian car park gas detection standards. The car park carbon monoxide sensors (GDA 2525) are designed to be unobtrusive, simple to install and calibrate. All systems manufactured by Gas Detection Australia are built, programed and calibrated in our factory prior to delivery and will only require wiring and connecting .

Designed, Manufactured and Supported in Australia.

Battery Room Monitoring

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Designed, Manufactured and Supported in Australia.

Cryogenic Room Gas Detection

Cryogenic freezing using liquid Nitrogen poses a problem of oxygen depletion. The GDA 2528 oxygen gas sensor offers a cost effective method of detection and low cost of maintenance. For standalone cyro-storage chambers housed in laboratories, the storage area can be monitored for oxygen depletion by the standalone GDA 40125 system.

Designed, Manufactured and Supported in Australia.

Laboratory and Classroom Monitoring

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Designed, Manufactured and Supported in Australia.

Specification NameSpecification Value
Detectable GasesCarbon monoxide (CO), Oxygen (O2), Ammonia (NH3), Hydrogen sulphide (H2S), Nitrogen Dioxide (NO2)
Detectable Gas RangesCO=200ppm; O2= 25%vol; NH3=100ppm; H2S= 100ppm; NO2= 30ppm
Power Requirements +24 VDC
Output Types4-20mA; 2 x SPCO alarm relays; 1 SPCO Fault relay; Alarm o/p, Optional MODBUS
Power Consumption 2 Watts
Output SpecificationsMax loop impedance 1K (24V)
ConnectionPlug in connectors
WiringTwo core min 0.75mm2 screened
Operating Temperature-10 - 40°C
Operating Humidity15% to 90% RH peak non condensing
Operating Pressure800 to 1200 mbar
Accuracy of Reading± 3% of full scale reading in standard operating environment
Warm Up Time30 seconds
Response TimeT90 = 45 seconds at SATP (Standard Ambient Temperature and Pressure)
Zero Drift< 0.1% / 30 days
Calibration Drift< 0.25% / 30 days at SATP (Standard Ambient Temperature and Pressure)
Sensor TechnologyElectrochemical Cell
Calibration RequirementAnnually with 6 monthly functional tests if sensor operated in standard operating environment
Warranty12 months from date of dispatch
Dimensions155mm x 130mm x 65mm (W x H x D)
Enclosure MaterialABS plastic & Brass C385
Enclosure RatingBrass Sensors (CO & O2) IP43 | PTFE Sensors IP22
Cable EntryUser provided

GDA 40125 Toxic / Oxygen Gas Detector

  • GDA 40125 Fixed Toxic / Oxygen Gas Detector Controler & Sensor Module
  • User Manual
  • Australian Factory Certificate of Calibration
Part Number Gas Range Replacment Sensor Module
40125-001 Carbon Monoxide (CO) 0-200 ppm 2525-002
40125-002 Oxygen (O₂) 0-25% Vol 2528-002
40125-004 Ammonia (NH₃) 0-100 ppm 2526-002
40125-005 Hydrogen Sulphide (H₂S) 0-100 ppm 2529-002
40125-006 Nitrogen Dioxide (NO₂) 0-30 ppm 2527-002



Part Number Image Description
4012X-001   GDA 4012X Series RS485 Modbus Output Addon Card
GC01-001 Gassing Cap with 500mm Length vinyl tubing
PSP1-24-075 Australian Mains Plugpack Power Supply. Output: 0.75 A @ 24 VDC
PSE Enclosed 24 VDC Power Supply




PSP : Plugpack 24 VDC Power Supply

The PSU P24 is an AC-DC plugpack power supply with an output of 24 VDC at 0.75A. The plugpack has a 3m cable with a 2.1 mm DC plug.

AVR 20 : Alarm Flasher and Sounder

This sounder/flashers operates at 24VDC. The sounder can be permanently disabled so that unit acts as a flasher only. These units are designed for internal use. These are available in Red or Amber.

CALGAS : Calibration Gas

To test and maintain accuracy gas detection systems require regular testing and calibration. GDA can provide you with a complete line of calibration equipment to calibrate all of our gas sensors and detectors. Our calibration gas cylinders all come with N.I.S.T. certification and ISO 17025 approval so you can be confident that you will receive gas with the highest accuracy levels.