Parameter category
IAQ Detectors, the instrumentation brand of Ace Instruments, manufactures CE certified wall-mount and duct-type carbon monoxide transmitters for parking garages, mechanical rooms, generator rooms, and commercial buildings. Each instrument uses electrochemical CO detection and outputs via Modbus RS-485, 4-20mA, or relay for direct BMS and fan-control integration.
Carbon monoxide is colourless and odourless, making continuous instrumentation the only reliable detection method. WHO guidelines set an 8-hour exposure limit of 25 ppm, while OSHA 29 CFR 1910 sets an 8-hour time-weighted average workplace limit of 50 ppm.
CO level reference — ppm
CO monitoring uses a fixed electrochemical transmitter to continuously sample carbon monoxide concentration in spaces where combustion sources or vehicle exhaust are present, such as parking garages, generator rooms, and boiler plants. Readings feed the BMS or a dedicated alarm panel to trigger exhaust fans or occupant warnings before concentrations reach unsafe levels.
Referenced standard: OSHA 29 CFR 1910, General Industry Air Contaminants
An electrochemical CO cell oxidises carbon monoxide at a sensing electrode, generating a current proportional to gas concentration. This method gives stable, linear output across the 0–500 ppm range typical of commercial CO monitoring, without the drift associated with older semiconductor-type elements.
Standard-cited ppm levels used to configure alarm setpoints
| CO Level | Status | Standard / Source | Health / Operational Effect |
|---|---|---|---|
| 9 ppm | Long-term reference | WHO annual average | Maximum safe long-term exposure |
| 25 ppm | Short-term reference | WHO 8-hour average | Maximum safe 8-hour exposure |
| 35 ppm | Common alarm setpoint | US parking garage alarm convention | Standard alarm setpoint |
| 50 ppm | Workplace limit | OSHA 8-hr TWA | Regulatory workplace limit |
| 200 ppm | Acute exposure | ACGIH | Headache within 2–3 hours |
Quick specification reference across the range
| Feature | Carbon Monoxide Transmitter | Duct Carbon Monoxide Transmitter |
|---|---|---|
| Mount type | Wall | Duct / In-line |
| CO detection | ✓ | ✓ |
| Relay output | ✓ | — |
| Modbus RS-485 | ✓ | ✓ |
| 4-20mA | ✓ | ✓ |
| Best for | Parking garages, mechanical rooms | AHU, HVAC ducts |
Where continuous CO monitoring is required
Parking structures
Enclosed and semi-enclosed parking garages require continuous CO monitoring to trigger exhaust ventilation before concentrations reach alarm thresholds.
Mechanical & generator rooms
Combustion equipment rooms are monitored continuously for CO buildup from incomplete combustion or exhaust leakage.
Hospitals & clinics
Boiler and plant rooms adjacent to occupied hospital areas are monitored per ASHRAE 170-2021 mechanical safety provisions.
Commercial buildings
Underground parking and loading dock areas in commercial buildings integrate CO transmitters with BMS-controlled exhaust fans.
Educational institutions
Boiler rooms and bus loading areas at schools are monitored for CO per NBC India mechanical safety guidance.
Industrial facilities
Enclosed production areas with combustion-based equipment monitor CO continuously for worker safety compliance.
Answers referenced against WHO, OSHA and ACGIH exposure limits
WHO guidelines set a long-term annual average limit of 9 ppm and an 8-hour exposure limit of 25 ppm, while OSHA sets an 8-hour time-weighted average workplace limit of 50 ppm. IAQ Detectors CO transmitters are configured to alarm well below these thresholds so exhaust ventilation can respond before concentrations become hazardous.
An electrochemical cell oxidises carbon monoxide at a sensing electrode, producing a current proportional to gas concentration. This provides stable, drift-resistant readings suited to continuous monitoring in parking garages and mechanical rooms.
Wall-mount CO transmitters sample ambient air in occupied or semi-occupied spaces such as parking garages, while duct-mounted transmitters install inline within HVAC ductwork to sample supply or exhaust air and feed data directly to the AHU or BMS.
CO transmitters are typically installed in enclosed parking structures, generator and boiler rooms, and mechanical plant areas, where a common alarm convention triggers exhaust ventilation at 35 ppm per US parking garage practice.
Yes. IAQ Detectors CO transmitters output via Modbus RS-485 RTU or 4-20mA, with relay contacts available on wall-mount models for direct fan-start or alarm-panel integration.
Expert guidance
Our application engineers will recommend the right instrument based on your space type, ventilation design, BMS integration, and compliance requirements. Most enquiries answered within 24 hours.