Why calibrate your CO2 sensor?
All gas sensors, whether measuring carbon dioxide (CO2), oxygen (O2), ammonia (NH3), or combustible gases require regular calibration to maintain accuracy and reliability over time.
Gas sensors naturally experience drift, a gradual deviation in readings caused by aging components, environmental exposure, or sensor poisoning. Without calibration, this drift can lead to inaccurate readings, creating serious risks in environments such as laboratories, pharmaceutical facilities, manufacturing plants and confined spaces.
Calibration ensures that your gas detection system:
- Provides accurate, real-time measurements
- Meets OSHA, NFPA and safety compliance requirements
- Protects personnel from hazardous exposure
- Maintains data integrity for audits and inspections
While this article references CO2 sensors as a common example, these principles apply broadly across all gas detection technologies.
What is Sensor Calibration?
To combat sensor drift, during calibration a sensor is exposed to one or more known gases with different amounts of CO2. The difference between the new reading and the original reading when the sensor was originally calibrated at the factory is stored in EPROM memory. This “offset” is then automatically added or subtracted to any subsequent readings taken by the sensor during use.
5 Types of Calibration Explained
1. Zero Point Calibration
Zero calibration exposes the sensor to a gas with no presence of the target gas (e.g., nitrogen for CO2 or clean air for some sensors). This resets the baseline reading.
2. Span (Two-Point) Calibration
Span calibration uses two known gas concentrations, typically a zero point and a higher concentration to establish the sensor’s response curve.
3. Multi-Point Calibration
Used in high-precision environments (labs, pharma), this method calibrates at multiple concentrations to improve accuracy across the full measurement range.
4. Fresh Air Calibration
Uses ambient air (400 ppm CO2) as a reference point. Best suited for portable or IAQ applications where simplicity is prioritized over precision.
5. Automatic Calibration (ABC or Algorithm-Based)
Sensors self-adjust over time using baseline assumptions. Effective in stable environments but not suitable for continuous or high-exposure applications.
Learn more about ABC calibration here.
What Gases Require Calibration in Industrial, Laboratory, and Safety Applications?
Calibration requirements vary depending on the gases present in your environment and the level of accuracy required.
Common gases requiring routine calibration include:
- Carbon Dioxide (CO2) – IAQ, incubators, beverage systems
- Oxygen (O2) – Critical for detecting deficiency or enrichment
- Carbon Monoxide (CO) – Toxic gas monitoring
- Ammonia (NH3) – Refrigeration and industrial processes
- Hydrogen (H2) – Flammable gas used in labs and manufacturing
- Methane (CH4) / LEL gases – Explosion risk monitoring
In laboratory and pharmaceutical environments, multi-gas calibration is often required, as multiple gases can impact both personnel safety and experimental outcomes.
Common Questions about Gas Sensor Calibration
Do gas sensors need calibration?
Yes. Over time, all gas sensors need calibration to maintain accuracy. Even sensors that use ABC Calibration (see above) function best with regular calibration. Read the user's manual for the manufacturers recommended calibration interval.
How often should a gas sensor be calibrated?
The more accurate the gas reading required, the more often it should be calibrated. However, CO2Meter staff typically recommends customers to place their sensors or devices on a regular calibration cycle like their important devices and equipment.
For specific industries we recommend the following calibration cycles and methods:
- Scientific Experimentation – zero calibration before each test
- Safety – zero calibration at least annually
- Beverage/Restaurant - zero with nitrogen at least annually
- Indoor Greenhouse – zero with nitrogen after each growing cycle
- Manufacturing – zero with nitrogen at least annually
- Indoor Air Quality – ABC or fresh air as desired
These are general guidelines. Calibration schedules may also be dictated by experimental protocols or by particular industrial standards. Be sure to consult your specific sensor requirements for your application.
How do I know if my gas detector is bad?
The easiest way for example when looking at a co2 gas detector, is to test the sensor by taking your CO2 detector outdoors. Since fresh air has about 400 ppm carbon dioxide, your CO2 detector should measure the same.
Another quick test is to simply blow into the CO2 detectors' sensor opening. Human breath contains about 3,000 ppm CO2. The detector should quickly notice a rise in the CO2 level. Once you quit blowing on it, the detector should return to a normal CO2 level.
How long do gas sensors last?
Sensor lifespan varies by technology:
- NDIR sensors: 5–15 years (CO2 and some hydrocarbons)
- Electrochemical sensors: 2–3 years (O2, CO, H2S)
- Catalytic bead sensors: 4–5 years (combustibles)
- Metal oxide sensors: 10+ years
Even long-life sensors still require regular calibration to maintain accuracy.
Can I calibrate my own gas detector?
Absolutely. Business safety department employees do it all the time. In general, you'll need a cylinder of calibration gas(s), a regulator a calibration bag and some tubing Simply reference your devices calibration procedure in the product manual for instructions. for your specific gas detector, monitor, or sensor.
The challenge is that in a business or factory if an employee is overcome by gas the lawyers will want to see a certificate of calibration. For this reason, many small businesses prefer to have their devices calibrated yearly by the supplier.
Annual Calibration Services for CO2Meter Fixed Gas Safety Systems
Overall, maintaining the accuracy and reliability of your CO2Meter fixed gas safety system is critical to ensuring compliance and protecting personnel from hazardous exposure. CO2Meter offers professional annual calibration services for all of our fixed gas detection safety systems, helping you stay aligned with OSHA, NFPA, and local fire code requirements.
Further, our expert gas safety technicians use certified calibration gas to verify sensor accuracy and make adjustments as needed, providing documentation for your safety records and inspections. Whether your system is installed in a restaurant, brewery, industrial fill plant or lab; our calibration services ensure continued peak performance and peace of mind. We offer on-site service options or fast turnaround with our mail-in program, depending on your needs and requirements.
To learn more about our CO2Meter gas equipment services, or to schedule a calibration today, click here to learn more.
For more information on specific calibration steps and procedures, you can also contact us.
