Why use a Gas Detector?

With the increasing focus on indoor healthy air quality and energy efficiency, the demand for gas detection instruments and IAQ controllers has been increasing in the HVAC market recently. Specifically, a common type of Gas Detector/vent controller is a CO2 or carbon dioxide Detector. These controllers sense carbon dioxide levels and, once they reach a high enough level, send a signal to control ventilation to remove and replace air in the space. Typically, these sensors will send a proportional signal to the damper motor, which will adjust accordingly to allow fresh air into the space. Additionally, many controllers have relays that will open or close contacts to turn power to the exhaust and/or supplemental fan on or off.

Carbon dioxide, carbon dioxide Detectors monitor spaces occupied by people or animals to remove excess carbon dioxide as a by-product of breathing. High levels of carbon dioxide have been linked to what's known as "sick building syndrome." Most building codes require a certain amount of make-up or turnover of the air to avoid large build-up of CO2 and the resulting health problems. Typically, a CO2 Detector has an adjustable setpoint, an analog signal, and one or more relays.

Carbon monoxide and nitrous oxide, CO, NO2, Detectors are used in spaces where internal combustion engines are operated: parking garages, service garages, small engine workshops, warehouses, underground garages, generator rooms. Carbon monoxide is a byproduct of gasoline combustion, while nitrogen dioxide is a byproduct of diesel combustion. Much like CO2 controllers, these units monitor the gas and send a proportional analog signal, and/or make a relay contact a stage fan to displace toxic air in a given space.

While it is possible to just maintain a constant ventilation rate, this is generally not preferred as the ventilation rate should match demand and often varies with these gases. Additionally, building ventilation and associated building pressure should be in balance, as discussed in a previous article. Therefore, a demand control system is desirable in most cases. This type of system will remove toxic air as needed while replacing it with an equal amount of fresh make-up air. The driving factor in the system is a properly applied IAQ Gas Detector/controller.