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.

Breathing Air Carbon Dioxide (CO2) Contamination Monitor

Normal CO2 levels outdoors (i.e. 200 – 400 ppm) or indoors (i.e. 500 – 2,500 ppm) are not considered hazardous. However, compressed air with CO2 levels that are within the “indoors range” can create problems in Self-Contained Breathing Apparatus (SCBA) applications. Some compressors might be equipped with filters to reduce CO2 levels. CGA G-7.1 lists a 1,000 ppm maximum for Grade D and a 500 ppm maximum for Grade E air. High CO2 levels in SCBA tanks can produce many of the same symptoms as CO poisoning. In addition, high CO2 levels increase breathing rates, which shorten SCBA usage time. One of the most common causes of SCBA air quality failures is excessive CO2 content.


Sigma 95H-WH-B-A

for continuous monitoring of multiple gases

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
Display: 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: IP65
Other configurations: On request