SI-100 is an IEC Ex fixed gas detector installed where potential gas hazard occur to measure and monitor oxygen, toxic gas and combustible gas. Utilising magnetic switchs so that Hot Work permit not required for calibration.

Locally Technically Supported by Gas Detection Australia

IECEx Approved

Through the LCD display the SI-100 shows the concentration of gases present and the status of the unit in real time. Connected to a controller or PLC with a standard 4-20mA analog output.

  • Low Cost and Reliable
  • IP65 Waterproof
  • Large Digital LCD
  • No Hot Work permit required
  • Australian Certificate of Calibration

Related Products

Sewage Treatment Plant Monitoring

The presence of Hydrogen Sulphide  can be detected by using the Gas Detection Australia GDA 2529 gas sensor to detect leaks of Hydrogen Sulphide  and evoke deodorisation plant. The SI-100C gas sensor can be used to monitor for leaks of LEL levels of methane gas. In digester applications Carbon dioxide can be detected using the GDA 4350  

Designed, Manufactured and Supported in Australia.

Battery Room Monitoring

The SI-100C and a range of associated Gas Detection Australia controllers can be used in battery room gas detection  to detect hydrogen in battery rooms and sound alarms. The battery room gas detection systems comprise of a hydrogen gas sensor SI-100C and a gas sensor control unit. The Gas Detection Australia control unit  GDA 4020 or GDA 4011 is situated external to the battery room to display the gas concentrations and the alarm status. The battery room gas detection system can then be interfaced to extraction fans, sounders or other apparatus. For smaller battery charging rooms the standalone GDA 40126 can provide an integrated sensor and controller with outputs to drive extraction fans and sounders.

Designed, Manufactured and Supported in Australia.

Hazardous Areas (IEC Ex Certified)

IEC Ex approved gas detectors and sensors for use in Zone 1 and Zone 2 areas within Australia for both Toxic and Flammable gases.

Hazardous Areas are areas in which an explosive gas atmosphere is or may be expected to be present, in quantities such as to require special precautions for the construction installation and use of equipment construction, installation and use of equipment. Hazardous areas are classified into 3 zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows:

  • Zone 0 - Area in which an explosive gas atmosphere is present continuously or for long periods or frequently.
  • Zone 1 - Area in which an explosive gas atmosphere is in which an explosive gas atmosphere is likely to occur in normal likely to occur in normal operation occasionally.
  • Zone 2 - Area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist will persist for a short period for a short period only.
  • Non hazardous area (safe area) - A non hazardous area is an area in which an explosive atmosphere is not expected to be present.

As per IEC60079-10-1 and AS/NZS 60079.29.2:2016

Specification NameSpecification Value
Detectable GasesSee Ordering Information for the full list of gas types and specifications
Accuracy of Reading±3% / Full scale
Operation mode displayLCD alarm display, LCD Backlight, Indicator LED, Buzzer (90dB at 10cm)
Measuring value displayDigital LCD Display (4-digit)
Parameter controlFront 3 magnetic switch (calibration, maintenance, alarm setting)
Power Requirements10 ~ 36 VDC (24VDC normal)
Power Consumption600 mA
Output TypesAnalog: 4-20mA & 2x Relays. Digital: RS-485 (Option)
Connection3 way plug connector
WiringPower + Signal cable : 3-wire 1.5sq (AWG16) / 2,500m max
Conduit connectionNPT 3/4" (2way)
Alarm StagesAlarm value(1, 2 alarm) | Alarm time (instant & delay) 1~30 min | Alarm dead band | Relay output on/off
Operating Temperature-20℃ ~ +55℃
Operating Humidity5% to 95% RH(Non-condensing)
Dimensions150 (W) x 165 (H) x 110 (D) mm
Enclosure MaterialAluminium, Stainless Steel (STS304)
Enclosure RatingIP65
ApprovalEx d IIC T5 (IECEx), CE EMC, ATEX, TR CU, CPA, CNEx, Inmetro, PESO
Warranty24 months from date of dispatch
Calibration RequirementEvery year with 6 monthly functional tests if sensor operated at SATP

 SENKO SI-100 Fixed Gas Detector

  • SI-100 Fixed Gas Detector
  • Calibration Cap
  • User Manual
  • Calibration Certificate
Part Number Gas Sensor Technology Range Resolution Sensor life time
SI-100-001 Oxygen (O₂) Electrochemical 0-30% Vol 0.1% Vol > 18 Months
SI-100-002 Carbon Monoxide (CO) Electrochemical 0-500 ppm 1 ppm > 2 Years
SI-100-003 Sulfur Dioxide (SO₂) Electrochemical 0-20 ppm 0.1 ppm > 2 Years
SI-100-004 Hydrogen (H₂) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-005 Hydrogen (H₂) Electrochemical 0-1000 ppm Within 5 ppm > 2 Years
SI-100-006 Hydrogen Sulfide (H₂S) Electrochemical 0-100 ppm 1 ppm > 2 Years
SI-100-007 Hydrogen Sulfide (H₂S) PID 0-50 ppm 0.1 ppm > 6 Months
SI-100-008 Hydrogen Peroxide (H₂O₂) Electrochemical 0~10ppm 0.1ppm > 2 Years
SI-100-009 Combustible Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-010 Combustible IR 0-100% LEL 1% LEL > 2 Years
SI-100-011 Ammonia (NH₃) Electrochemical 0-100 ppm 1 ppm > 2 Years
SI-100-012 Acetylene (C₂H₂) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-013 Ethanol (C6H5OH) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-014 Ethylene (C₂H4) Catalytic 0~100%LEL 1% LEL > 5 Years
SI-100-015 Ethylene Oxide (C2H4O) IR 0-100% LEL 1% LEL > 2 Years
SI-100-016 Ethylene Oxide (C2H4O) Electrochemical 0~30 ppm 0.1 ppm > 2 Years
SI-100-017 Toluene (C6H5CH3) IR 0-100% LEL 1% LEL > 2 Years
SI-100-018 Toluene (C6H5CH3) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-019 Acetic Acid (CH3COOH) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-020 Methane (CH4) IR 0-9999 ppm Within 20 ppm > 2 years
SI-100-021 Methane (CH4) IR 0-100% LEL 1% LEL > 2 years
SI-100-022 Methane (CH4) IR 0-100% Vol 1% Vol > 2 years
SI-100-023 Methanol (CH3OH) Catalytic 0-100% LEL 1% LEL > 5 Years
SI-100-024 Chlorine (CL₂) Electrochemical 0-5 ppm 0.1 ppm > 2 Years
SI-100-025 Chlorine (CL₂) Electrochemical 0-20 ppm 0.1 ppm > 2 Years
SI-100-026 Carbon Dioxide (CO₂) IR 0-2000 ppm Within 3 ppm > 2 Years
SI-100-027 Carbon Dioxide (CO₂) IR 0-5000 ppm Within 3 ppm > 2 Years
SI-100-028 Carbon Dioxide (CO₂) IR 0-5% Vol 0.1% Vol > 2 Years
SI-100-029 Hydrogen Chloride (HCI) Electrochemical 0-10 ppm 0.1 ppm > 2 Years
SI-100-030 Volatile Organic Compound (VOC) PID 0-1000 ppm Within 3 ppm > 6 Months
SI-100-031 Xylene (C8H10) IR 0-100% LEL 1% LEL > 2 Years
SI-100-032 Nitrogen Monoxide (NO) Electrochemical 0~100ppm 1ppm > 2 Years
SI-100-033 Nitrogen Dioxide (NO₂) Electrochemical 0~20ppm 0.1ppm > 2 Years



Part Number Image Description
SI-100-### S SI-100

SI-100-### Replacement Sensor Head

SI-100 Magnetic Bar   Magnetic bar for controlling SI-100 Units
SI-100 Filter   Replacement sintered metal filter
SI-100 Plug   PT 3/4
SI-100 Calibration Cap   Calibration Cap for SI-100 & SI-100C


  • Flammable Catalytic Sensor Models
    • Poisoning: some compounds will decompose on the catalyst and form a solid barrier over the catalyst surface. This action is cumulative and prolonged exposure will result in an irreversible decrease in sensitivity. The most common of these substances are: volatile lead or sulphur containing compounds; silicones; phosphates.
    • Inhibition: certain other compounds, especially hydrogen sulphide and halogenated hydrocarbons, are absorbed or form compounds that are absorbed by the catalyst. The resultant loss of sensitivity is temporary and in most cases a sensor will recover after a period of operation in clean air


  • Electrochemical Sensor Models
    • Poisoning: Senko 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.


  • Oxygen Electrochemical Sensor Models
    • Poisoning:  Acid gases such as CO₂ and SO₂ will be absorbed by the electrolyte and tend to increase the flux of oxygen to the electrode. This gives an enhanced oxygen signal of approximately 0.3% of signal per 1% CO₂. Senko oxygen sensors are not suitable for continuous operation in concentrations of CO₂ above 25%.

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.

IS-A105N : Intrinsically Safe Alarm Sounder

The IS-A105N is a high output, 105dB alarm sounder. Suitable for all intrinsically safe signalling applications including fire, security and process control.

IECEx Approved

IS-L101L : Intrinsically Safe LED Beacon

The IS-L101L unit is an intrinsically safe field mounting beacon which provides a bright
flashing warning signal.

IECEx Approved