Breathing / Rescue Air Contamination Monitors

The dangers associated with breathing contaminated air are also well known and especially critical when using SCBA tanks in emergency situations.

Sigma Sensing has solutions for individual or multiple contaminant monitoring of breathing or rescue air.


Occupational Safety and Health regulations require procedures to ensure adequate quality of breathing air contained in breathing apparatus (SCBA).
SCBA is a device worn by rescue workers, firefighters, paramedics and others working for example on ships & oil rigs to provide breathable air in an immediately dangerous to life or health atmosphere (IDLH).


SCBA fill station air quality monitoring
Air filling in fire stations typically refers to the process of filling self-contained breathing apparatus (SCBA) cylinders with compressed air. Firefighters use SCBA to breathe while operating in hazardous environments, such as during firefighting operations in smoke-filled or oxygen-deficient areas.
Monitoring the air quality during the filling of Self-Contained Breathing Apparatus (SCBA) cylinders is critical to ensure the safety and reliability of the breathing air supplied to firefighters. Contaminated or poor-quality air can jeopardize the effectiveness of SCBA and put firefighters at risk.
Fire departments and agencies often follow established air quality standards, such as those set by the National or local regulatory bodies. These standards dictate the acceptable levels of contaminants, including gases, particulates, and moisture, in the breathing air.
Air quality monitoring and maintenance of the air filling equipment are crucial to ensure that firefighters receive the highest quality breathing air when using SCBA during their operations. It helps minimize health risks and ensures the SCBA equipment operates effectively in hazardous environments.


Sigma 606 24/7 Continuous Breathing Air Analyser

Sigma 606 is a wall mounted breathing air analyser for continuous monitoring in accordance with EN 12021. This instrument measures gas concentrations for oxygen (O2), carbon dioxide (CO2) and carbon monoxide (CO) in addition to dew point and oil vapour with programmable alarm settings for out of range alarms.

24/7 breathing air monitoring reduces the risk to users from quality issues that might occur between periodic testing and Sigma 606 system does not require regular user input to function reliably. Indeed, once the system is installed, the single pneumatic connection made and the power and signal connections established, the system can be relied on to provide alarm signals whenever the parameters exceed preset safe thresholds.

The easy to read touch screen display offers at-a-glance indication of the measured parameters in real time so that any operator can understand the air quality reading without fear of misinterpretation or needing specific training. The touchscreen menu system allows easy viewing and adjustment of the alarm settings and has an integral datalogger and PDF report generator for spot checks and specific testing.

Communication to BMS/SCADA systems or the dedicated S4A software is through Modbus TCP/RTU and there is an optional 4G dongle to enable wireless communication. Traditional local alarms can be wired through an optional 8 way relay expansion should that be needed.

S606 offers 24/7 breathing air user safety through continuous measurement from a self contained stand-alone system that only requires periodic calibration through exchange sensor modules that can be fitted by the user. There is no need for highly trained specialists or external contractors for this and the comprehensive instruction manual provides all the information and training needed.

• O2 0-25%
• CO2 0-1000ppm
• CO 0-20ppm
• H2O -100 +20degC TD
• Oil Vapour 0.001 – 5.000mg/m3
• Pressure 0-16bar
• Modbus TCP/RTU Communication
• Programmable alarms
• PDF report generator
• Integral data logger

The S606 is perfect for monitoring breathing air quality continuously, but if you need mobile intermittent testing capability, the S605 is the perfect solution.

Sigma Sensing is offering for this purpose a fixed installation unit of the Sigma95H-B series with display that can monitor the correct levels of CO2 and CO (NOx optional) in the air system. The unit which is designed for industrial applications is using a long life NDIR CO 2 sensor and an electrochemical CO sensor for this purpose.. The sensors monitor the air in ambient pressure as the compressed air pressure is reduced to ambient pressure for air sampling in a low pressure measurement chamber.
Version Sigma 95H-B-A with an alarm beacon and the alarm setting freely configurable is also available.

Breathing Air Quality Monitor, Fireman CO2 protection, Scuba Diver protection 

Sigma 95H-B series Specifications


System max pressure: <15 bar
Response time ≤30 seconds (T90)
Sensor measuring range: 

CO2: 0 ~2000 ppm

CO: 0-50 ppm

Sensor operating principle:

CO2: Non-dispersive infrared (NDIR)

CO: Electrochemical -

Accuracy :  ≤±5%F.S. (higher accuracy optional)
Sensor operating humidity: 0 - 95% RH, non-condensing
Sensor operating temperature: -20.....+50C
Gas sampling method: suction pump
Sensor operating life expectancy:

CO2: 5 years in air

CO: 18-24 months in air

Recommended calibration interval: 12 months


2.4-inch color display, resolution 320*240

Display content: gas molecular formula, concentration, unit, pump status, etc.
Power supply: 12-24V DC
Current outputs (for one sensor): 4-20mA
Relay output: 1
Other outputs RS485

Alarm mode:



buzzer, alarm status prompt on the display screen, high and low alarm values can be set by end user.

Protection rating:


Other configurations:

On request