CO₂ sensors by Gas Sensing Solutions have a history of being used in challenging applications. For example, the CozIR®-A CO2 sensor was specifically designed to withstand harsh environments and was chosen to be used on the International Space Station to monitor air quality.
In confined spaces such as an aircraft cabin and cockpit, it is common for CO₂ levels to be higher than experienced in fresh air. Although it is well known that increased levels of carbon dioxide will have an impact on health, including headaches, sleepiness, poor concentration and cognition and loss of attention, CO₂ levels in aircraft are not currently intelligently managed.
Aircraft are fitted with an Environmental Control System (ECS) to provide protection, comfort, and life support for passengers onboard. These systems monitor and control the environment for passengers and crew but are inflexible and poor at understanding the real air quality.
To keep the CO₂ levels below a mandated upper limit, outside air must be drawn in through the engines of the aircraft. Doing so is important for passenger wellbeing, aircrew cognition and reduction of pollutants and viruses. Whilst it is agreed that this is important, drawing in more fresh air than necessary raises fuel consumption and thus operating costs. The air being drawn into the aircraft is defined by design and not as a result of monitoring real time air quality.
Adding distributed CO₂ sensors to populated areas of the aircraft can improve the intelligence of the ECS, as measuring levels of CO2 indoors is a good indicator fresh air. Adding CO₂ sensors could help improve the ECS capability and allow the aeroplane operator to actively optimise air quality in real time and ensure there is an ideal balance between CO₂ levels, the safety and comfort of staff and passengers, and minimising operating costs.
The starting point is to know CO₂ levels at various points around the aircraft. The sensor needs to be able to cope with the challenging in-cabin environment, as it will be affected by temperature, vibration, and barometric pressure changes.
GSS has designed a CO₂ sensor specifically for high integrity aerospace applications and which meets the full extent of the DO-160 standard, the Environmental Conditions and Test Procedures for Airborne Equipment.
GSS carbon dioxide sensors are all solid-state designs, which provides an intrinsic immunity to being placed in a noisy and stressful environment. This is crucial as changes to the sensor caused by mechanical vibration cannot easily be corrected.
A pressure compensation algorithm was also developed to work within the operating flight level envelope of the aircraft. On-board the sensor, each CO₂ reading is adjusted using this algorithm in real-time to provide pressure adjusted CO₂ measurements.
The sensors can be used to optimise in-cabin air quality by monitoring CO₂ levels in near real-time and manage the volume of fresh air used by the ECS, helping to balance air quality and operating costs.