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Brand: General Monitors
General Monitors IR400-0-01-1-2-0-1-0 Point IR Gas Detector
Description
Overview
The General Monitors IR400 is a point infrared gas detector built for continuous, reliable detection of combustible hydrocarbon gases and vapors in industrial hazardous areas. Using dual-wavelength infrared absorption rather than a catalytic bead sensor, the IR400 avoids the sensor poisoning risk that silicone, sulfur, and lead compounds pose to catalytic detectors, while delivering fast response even through a splash guard.
As part of General Monitors’ (an MSA Safety brand) established point gas detector range, the IR400 is engineered for demanding oil, gas, and petrochemical environments where continuous, unattended gas monitoring is a safety-critical function. Seven Star LLC supplies the General Monitors IR400 as a trusted MSA Safety/General Monitors supplier to industrial facilities across Oman and the GCC.
Operating Principle
The IR400 measures gas concentration by comparing infrared absorption at a wavelength specific to hydrocarbon molecules against a reference wavelength unaffected by the target gas, calculating gas concentration from the difference. This dual-wavelength infrared approach is immune to the catalytic-poisoning failure mode that silicone vapors, sulfur compounds, and leaded fuels can cause in bead-type combustible gas sensors, and the detector achieves a T90 response of 3 seconds or less even with a splash guard installed — among the fastest response times in its class.
Engineering Design of the General Monitors IR400
The IR400 monitors within the lower explosive limit (LEL) range across approximately 45 combustible hydrocarbon gases and vapors, including methane, propane, butane, ethane, ethylene, gasoline, jet fuel, benzene, and xylene, covering the majority of hydrocarbons encountered in oil and gas processing. Output is provided as an industry-standard 4–20mA signal, with options for Modbus and HART digital communication for integration into modern gas-detection and control systems. The detector is housed in an explosion-proof enclosure rated for hazardous-area installation.
Key Features
- Dual-wavelength infrared detection, immune to sensor poisoning
- Detects ~45 combustible hydrocarbon gases and vapors
- T90 response ≤3 seconds, even with splash guard installed
- 4–20mA output, with Modbus and HART options
- Explosion-proof housing for hazardous-area installation
- No catalytic bead to poison or degrade over time
- Monitors within the lower explosive limit (LEL) range
- Part of General Monitors’ (MSA Safety) established gas detection range
Industrial Applications
The IR400 is specified for continuous combustible-gas monitoring in refineries, gas processing plants, and petrochemical facilities across Muscat, Sohar, and Salalah, where hydrocarbon leaks from process equipment, pipelines, or storage present a fire and explosion risk. Its resistance to catalytic poisoning makes it particularly suited to environments with silicone-based products, sulfur compounds, or leaded fuels present, where a traditional catalytic detector would need frequent recalibration or replacement.
Across the GCC’s oil, gas, and petrochemical sectors, the IR400’s fast response time supports early leak detection and automatic shutdown or ventilation interlocks, helping facilities meet safety case requirements for combustible-gas monitoring in process areas, compressor stations, and loading facilities.
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | General Monitors IR400 |
| Detection Technology | Dual-wavelength infrared absorption |
| Gases Detected | ~45 combustible hydrocarbons (methane, propane, benzene, etc.) |
| Measurement Range | 0–100% LEL |
| Response Time | T90 ≤3 seconds (with splash guard) |
| Output | 4–20mA, Modbus, HART options |
| Enclosure | Explosion-proof |
| Accuracy at 25 °C | ±3 % LEL up to 50 % LEL; ±5 % LEL above 50 % LEL |
| Zero drift | Less than 2 % per year |
| Response time with splash guard | T50 1.5 s or less, T90 3 s or less |
| Input power | 20 to 36 V DC, 24 V DC nominal, 200 mA max. |
| Analogue output | 0 to 21.7 mA, 600 Ω max. |
| Status current levels | Fault/start-up 0 mA; zero, calibration, gas check 1.5 mA; dirty optics 2.0 mA |
| RS-485 | Modbus RTU; 2400 to 19200 baud |
| Storage temperature / humidity | -50 to +85 °C; 10 to 95 % RH non-condensing |
| Dimensions / weight | 74 mm diameter × 225 mm; 1.35 kg aluminium, 2.7 kg stainless steel |
| Mounting / ingress protection | 3/4 in NPT; Type 4X, IP66 |
General Monitors IR400 Ordering Code and Options
The part number IR400-0-01-1-2-0-1-0 is the configuration that General Monitors lists as its standard build. Each group after the model name selects one option. The first digit is the output: 0 means analogue output with Modbus. Other codes select HART, Hazard Watch calibration or Modbus with a customer-specified address. The two-digit group is the calibration gas: 01 is methane. Further codes cover propane, benzene, hexane, pentane, ethylene, butane, ethane and propylene.
The next digit is the housing: 1 is aluminium and 2 is stainless steel, both with a 3/4 in NPT thread. The optical guard digit is 2 for a splash guard with screen, 1 for a splash guard without screen and 0 for none. The junction-box digit is 0 for no box. The last two digits are the standard approval set and no automatic remote gas calibrator.
So this exact unit is a methane-calibrated, aluminium-housed detector with 4-20 mA and Modbus, splash guard with screen, and no junction box. A HART output needs a different first option code.
General Monitors IR400 Installation and Wiring Notes
The detector is supplied from 24 V DC nominal (20-36 V DC) and draws up to 200 mA. With 14 AWG (2.0 mm²) cable the data sheet allows up to 1100 m between the power source and the detector. The output drops to defined levels below 4 mA to signal fault, zeroing or calibration, and dirty optics, so the receiving system should be configured to recognise them. The unit is factory-calibrated and needs no routine gas calibration; the manufacturer specifies periodic window cleaning and re-zeroing. Listed accessories include a junction box, duct-mount junction box, calibration cup, flow block and rain guard.
Request a Quote for General Monitors IR400-0-01-1-2-0-1-0 Point IR Gas Detector
Contact Seven Star LLC for pricing and availability on the General Monitors IR400 point IR gas detector across Oman and the GCC. Our team can help specify the correct gas detector configuration for your hazardous-area monitoring requirements.
Also available: General Monitors TG5000 Toxic and Combustible Gas Monitor
Datasheets & Documents
- Datasheet General Monitors IR400-0-01-1-2-0-1-0 Point IR Gas Detector Datasheet Download
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About brand
General Monitors makes fixed gas and flame detection systems for hazardous industrial sites. Four aerospace engineers founded the company in 1961 in El Segundo, California, to build hydrogen gas monitors for the US space program. It later moved to Costa Mesa and, in 1991, to Lake Forest, California. MSA Safety acquired General Monitors in October 2010, and its detectors are now sold as part of the MSA fixed gas and flame detection range.
Seven Star LLC is an independent supplier listing General Monitors gas detectors, flame detectors, ultrasonic leak detectors and replacement sensors for buyers in Oman and the GCC. Detectors and sensors are matched from the full model code on the label.
General Monitors company profile
| Origin | Founded in 1961 in El Segundo, California, by four aerospace engineers making hydrogen detection equipment for the US space program |
|---|---|
| Location | Lake Forest, California, USA (since 1991) |
| Ownership | Part of MSA Safety since 14 October 2010 |
| Product families | Catalytic and infrared point gas detectors, open-path infrared detectors, toxic gas sensors, multi-spectrum infrared and UV/IR flame detectors, ultrasonic gas leak detectors |
| Typical duty | Combustible gas, H2S and fire detection on wellheads, gas plants, refineries, offshore platforms and terminals |
Milestones
- 1961: Four aerospace engineers found the company in El Segundo, California, making hydrogen detectors for the US space program.
- 1991: The company moves to Lake Forest, California.
- 2010: General Monitors becomes part of MSA Safety on 14 October.
General Monitors detectors and sensors
| Model | Type | Typical use |
|---|---|---|
| S4000CH | Catalytic bead combustible gas detector | Point detection of flammable gases and vapours, including hydrogen |
| IR400 | Point infrared hydrocarbon gas detector | Methane and hydrocarbon detection without catalyst poisoning, and in inert atmospheres |
| IR5500 | Open-path infrared gas detector | Perimeter and line-of-sight monitoring across process areas and fence lines |
| TG5000, 51457-1 H2S sensor | General-purpose gas monitor; H2S replacement sensor (0-100 ppm) | TG5000 for combustible, toxic or oxygen monitoring in wastewater, utility and light industrial sites; 51457-1 for H2S detectors |
| FL4000H, FL5000 | Multi-spectrum infrared (MSIR) flame detectors | Hydrocarbon fire detection with resistance to false alarms from sunlight and hot work |
| FL500 | UV/IR flame detector | Hydrocarbon fire detection in compressor houses, pump rooms and loading areas |
| Observer-i | Ultrasonic gas leak detector | Detects the sound of pressurised gas leaks, including where wind disperses the gas before it reaches a point detector |
Where General Monitors detectors are used
Gas and flame detectors form the field layer of a fire and gas system. In Oman and the GCC they are installed on wellpads and gathering stations, gas processing and sulphur recovery units, refineries, LNG plants, tank farms, loading terminals, offshore platforms and power stations. A typical layout combines point detectors near leak sources, open-path detectors across process areas, ultrasonic detectors on high-pressure gas equipment and flame detectors covering fire zones.
Ordering General Monitors equipment: what we need
Send the full model code from the detector label, which defines gas type, range, output, housing material, thread and approvals, plus the serial number. For replacement sensors give the detector model and the gas and range of the installed sensor. For a new detector add the gas or fire hazard, area classification, output required (4-20 mA, HART, Modbus or relays), mounting and the certification needed on site, such as ATEX or IECEx.
Facts checked against MSA Safety and General Monitors company information, October 2026.
Browse General Monitors products by category: Fire & Gas Detectors.
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Frequently Asked Questions
What gases does the IR400 detect, and how fast does it respond?
It's an infrared point detector for combustible hydrocarbon gases and vapors (methane, propane, ethane, butane, hexane, pentane, ethylene, and others depending on sensor selection), with a T90 response time of 3 seconds or less, even with a splash guard fitted.
How does the IR400 communicate with the control system?
It offers a 4-20mA analog output, with Modbus and HART configurations available, giving flexibility for integration with existing gas detection and control room systems.
How does the detector distinguish a real fault from dirty optics?
It includes dirty optics indication that discriminates between an actual instrument fault and an optical surface that simply needs cleaning, reducing unnecessary maintenance call-outs.
Is the IR400 approved for hazardous areas, and is it available in different housing materials?
Yes, IECEx-certified sensor variants are available, and the detector can be ordered in either aluminum or stainless steel explosion-proof housings depending on the environmental corrosion requirements.
What accessories are available for installation and calibration?
Available accessories include a calibration cup, a hardware kit with regulator and tubing for applying calibration gas, and junction boxes in CSA/FM or ATEX/IECEx-rated aluminum or stainless steel variants, with or without integral switches.
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