Why the Sensor Coverage Range is Larger in Parking Garages

In many commercial applications, the coverage area for carbon monoxide (CO) gas detectors is primarily determined by their proximity to fuel-burning appliances and other potential sources of CO emissions. These sources may include boilers, furnaces, gas stoves, generators, and other combustion equipment or processes. The risk level increases significantly in occupied spaces, such as schools, offices, kitchens, chemical labs, and vehicle maintenance garages, where prolonged exposure to CO can pose serious health hazards. In such environments, detectors must be strategically placed to ensure rapid detection and response, near fuel-burning appliances and the presence of potential gas sources.

Conversely, low-occupancy or non-occupancy areas—such as parking garages—present a different risk profile. While CO can still accumulate due to vehicle emissions, the transient nature of human presence reduces the immediate exposure risk. As a result, sensor coverage in these areas may be broader, with detectors spaced farther apart and integrated into ventilation control systems to maintain safe air quality levels. The typical sensor coverage range for CO and NO2 in parking garages is around a 50 ft (15 m) radius per sensor, offering 360-degree detection, and here's why:

Open Layout and Air Movement

• Parking garages are often large, open spaces with minimal obstructions, allowing gases like CO and NO2 to disperse more evenly.
• Air movement from vehicles and ventilation systems helps distribute gases, making it feasible for a single sensor to monitor a wider area effectively.

Energy Efficiency Goals

• Ventilation systems in garages are energy-intensive. Using fewer sensors with larger coverage helps reduce installation and operational costs, especially when tied to on-demand ventilation control.
• Systems are designed to activate fans only when needed, based on sensor readings, which helps conserve energy.

Sensor Placement in the Breathing Zone

• CO is roughly the same density as air and tends to stay in the breathing zone (4—6 feet above the floor).
• NO2 while heavier than air, is emitted hot from diesel exhaust and initially rises before cooling and settling into the breathing zone.
• This predictable behavior allows for strategic sensor placement that maximizes coverage.

Regulatory and Safety Standards

• Standards like ASHRAE, IMC, and OSHA recommend gas detection systems that balance safety and energy efficiency.
• These standards often support larger coverage areas in garages due to the nature of the space and the intermittent presence of vehicles.