Ax60+ CO₂ Calibration Guide
Proof Testing and Calibration Explained
Regular calibration of CO₂ gas sensors is essential to ensure accurate readings and maintain a safe working environment. If gas monitors are not correctly maintained, they may fail to detect hazardous conditions, potentially putting personnel and operations at risk.
Routine proof testing and calibration help verify that sensors are functioning correctly and responding accurately to known gas concentrations.
This guide explains how to proof test and calibrate your Analox Ax60+ CO₂ sensor, helping you maintain measurement accuracy, support compliance requirements, and ensure ongoing safety.
What Is Gas Sensor Calibration?
Calibration is the process of comparing a gas sensor’s readings against a known reference gas concentration to verify and maintain accuracy.
Over time, gas sensors can drift from their original settings due to environmental conditions, aging components, or normal use. Calibration helps correct this drift and ensures the sensor continues to perform as intended.
In simple terms, calibration helps confirm that your gas monitor is:
- Measuring gas concentrations accurately
- Responding correctly to gas exposure
- Providing reliable alarms and safety warnings when required
Regular calibration is a key part of maintaining an effective gas detection system and ensuring ongoing workplace safety.
Why Is Calibration Important?
Without proper calibration, gas sensors can drift over time, reducing their accuracy and reliability. This can result in:
- Inaccurate gas readings
- False alarms
- Failure to detect hazardous gas concentrations
Regular calibration helps to:
- Maintain measurement accuracy
- Reduce unplanned downtime
- Protect personnel and operations
- Support compliance with safety standards and workplace regulations
By ensuring gas sensors continue to perform as intended, routine calibration plays a critical role in maintaining an effective gas detection system and a safe working environment.
Proof Test vs Calibration: What’s the Difference?
Understanding the difference is key:
Proof Test (Bump Test)
A quick check to confirm the sensor responds correctly to gas.
Calibration (Zero & Span)
Adjusts the sensor to restore accurate readings.
If a proof test fails, calibration is required.
How Often Should You Calibrate?
For the Analox Ax60+ CO₂ sensor, we recommend:
- Proof testing: At least every 12 months
- Calibration: Only if the proof test indicates the sensor is out of tolerance or drift has been detected
Additional calibration may also be required if:
- A high-level alarm event has occurred
- The sensor has been exposed to an incorrect calibration gas
- Routine maintenance has been missed or neglected
Following a regular proof testing schedule helps ensure the sensor continues to operate accurately while minimizing unnecessary calibration.
Equipment Required
Before beginning the proof test or calibration procedure, ensure you have the following equipment available:
- Push-in flow adaptor
- 2 m neoprene tubing
- 0.5–1.0 L/min flow regulator
- Calibration gas (3.0% CO₂, balance nitrogen)
- Zero gas (20.9% oxygen or clean air)
For convenience, Analox offers a complete Ax60+ CO₂ Check Kit, containing all the components required to perform routine proof testing and calibration. This helps simplify maintenance procedures and ensures you have the correct equipment for accurate sensor verification.
How to Perform a Proof Test (Bump Test)
- Ensure the Ax60+ is powered on and operating normally.
- Attach the tubing and flow adapter to the CO₂ sensor.
- Connect the regulator to the calibration gas cylinder.
- Apply the calibration gas to the sensor for 1–2 minutes.
- Verify that the displayed reading is between 30,000 and 30,150 ppm CO₂.
- If the reading is within this range, no further action is required.
- If the reading falls outside this range, proceed with sensor calibration.
Zero Calibration (First Step)
Before performing a span calibration, a zero calibration must be completed to establish an accurate baseline for the sensor.
- Access the calibration menu by pressing and holding Cancel and Cycle simultaneously.
- Select Zero Calibration from the menu.
- Connect a source of zero gas or expose the sensor to clean, fresh air as specified in the service manual.
- Apply the gas for 1–2 minutes.
- Allow the reading to stabilize.
- Confirm the calibration when prompted.
Important: Always perform a zero calibration before carrying out a span calibration. This ensures the sensor is correctly referenced and helps maintain calibration accuracy.
Span Calibration
To perform a span calibration on the Ax60+ CO₂ sensor:
- Select Span Calibration from the system menu.
- Set the calibration value to 3.0% CO₂.
- Apply the span gas to the sensor using the flow adapter and regulator.
- Allow the gas to flow for 1–2 minutes.
- Wait for the reading to stabilize.
- Confirm the calibration when prompted.
Once confirmed, the Ax60+ will store the new calibration values and return to normal monitoring operation. Always verify that the displayed reading is stable before accepting the calibration to ensure the best possible accuracy.
Troubleshooting Tips
To help ensure a successful proof test or calibration:
- Only calibrate one sensor at a time.
- Ensure the calibration gas is flowing correctly and that tubing is not kinked or blocked.
- Remove any splash guards or protective covers before applying calibration gas.
- If calibration fails, refer to the Ax60+ Service Manual and check any displayed fault codes before repeating the procedure.
Following these checks can help identify common issues and reduce unnecessary downtime during maintenance.
Troubleshooting Tips
To help ensure a successful proof test or calibration:
- Only calibrate one sensor at a time.
- Ensure the calibration gas is flowing correctly and that tubing is not kinked or blocked.
- Remove any splash guards or protective covers before applying calibration gas.
- If calibration fails, refer to the Ax60+ Service Manual and check any displayed fault codes before repeating the procedure.
Following these checks can help identify common issues and reduce unnecessary downtime during maintenance.
FAQs About Ax60+ Calibration
What is a bump test?
A proof test (or bump test) is a quick check using calibration gas to confirm that the sensor responds correctly and is operating as expected.
How often should I calibrate my Ax60+?
Annually, or whenever a proof test indicates drift.
Is there a video to show me how to calibrate the Ax60+?
Yes, please see below:
What happens if calibration fails?
A fault code may appear, indicating the need for further checks or servicing.
Can I calibrate the Ax60+ myself?
Yes. The Ax60+ is designed to be user-friendly, allowing operators and engineers to perform routine proof testing and calibration procedures quickly and efficiently.
Why is calibration important?
Regular calibration helps ensure accurate readings, protects personnel, and reduces the risk of dangerous gas exposure by verifying that the sensor responds correctly to hazardous conditions.
To learn more about the Ax60+, please click below:
Key Takeaway
Maintaining your Ax60+ CO₂ sensor through regular proof testing and calibration is essential for ensuring accurate and reliable gas detection.
A properly maintained system helps to:
- Protect personnel from hazardous gas exposure
- Maintain compliance with safety requirements
- Reduce the risk of costly incidents and downtime
If your environment uses CO₂, routine proof testing and calibration are not optional; they are critical components of an effective gas safety strategy.