Air Quality Monitors: Calibration Standards For Compliance

The Occupational Safety and Health Administration (OSHA) has established guidelines for indoor air quality, which businesses should follow to protect employees and patrons from poor air quality. While OSHA doesn't have specific regulations for gas detector calibration, it has released guidelines for calibrating and testing portable gas monitors. Calibration is essential to ensure the accuracy of gas detection and to prevent worker exposure to harmful gases. OSHA recommends calibrating gas detectors before each use and following the manufacturer's guidelines. Calibration testing is necessary when a monitor has been damaged or exposed to extreme conditions.

Calibration drift

• Degradation caused by exposure to phosphates
• Degradation of phosphorus-containing components
• Degradation of lead-containing components
• Gradual chemical degradation of sensors and drift in electronic components that occur normally over time
• Use in extreme environmental conditions, such as high/low temperature and humidity, and high levels of airborne particulates
• Exposure to high concentrations of target gases and vapours
• Exposure of catalytic hot-bead LEL sensors in instruments to volatile silicones, hydride gases, halogenated hydrocarbons, and sulfide gases
• Exposure of electrochemical toxic gas sensors to solvent vapours and highly corrosive gases
• Handling/jostling of the equipment causing enough vibration or shock over time to affect electronic components and circuitry

Operators should validate a DRPGM's operability when any of these conditions occur or are suspected during use. When attempting to calibrate an instrument after exposure to these conditions, the sensor will often display a failure message or not allow the operator to fully adjust the display reading.

Harsh operating and storage conditions can affect instrument performance, leading to inaccurate readings or even failure. While a DRPGM may appear undamaged during a visual inspection, it could be damaged internally. At this point, the operator should replace the damaged sensor or have it serviced by qualified personnel, following the manufacturer's instructions regarding sensor replacement and servicing.

Sensor poisoning

Understanding Sensor Poisoning

For example, combustible gas detectors used to detect explosive gases like butane are susceptible to sensor poisoning. Once they are exposed to these combustible gases, they can become inaccurate and fall "out of calibration." This means that even if the sensor is repaired or recalibrated, it may not provide accurate readings anymore.

Preventing Sensor Poisoning

To prevent sensor poisoning, it is crucial to follow the manufacturer's guidelines and recommendations for the specific air quality monitor or gas detector. This includes proper handling, storage, and maintenance procedures. Regular calibration and testing of the equipment are also essential to ensure its accuracy and reliability.

Additionally, it is important to be aware of the environment in which the air quality monitor is being used. Extreme environmental conditions, such as high or low temperatures, high humidity, and high levels of airborne particulates, can contribute to sensor poisoning. Proper storage and handling of the equipment, such as protecting it from physical damage and extreme conditions, can help prevent sensor poisoning.

Responding to Sensor Poisoning

If sensor poisoning is suspected or identified, it is crucial to take immediate action. First, refer to the manufacturer's instructions for any specific recommendations or procedures to address the issue. In some cases, it may be necessary to replace the sensor or the entire air quality monitoring device.

It is also important to identify and eliminate the source of sensor poisoning to prevent recurrence. This may involve removing the device from the contaminated environment, improving ventilation, or implementing engineering controls to minimize exposure to harmful substances.

The Impact of Sensor Poisoning on OSHA Compliance

Therefore, it is crucial for employers to regularly calibrate and maintain their air quality monitoring equipment, following the manufacturer's guidelines and OSHA recommendations. This will help ensure the accuracy of the monitors and maintain a safe working environment for employees.

Final Thoughts

Monitor abuse

• Physical Damage: Air quality monitors should be handled with care to avoid physical damage. Dropping, knocking over, or exposing the device to extreme temperatures or humidity can affect its accuracy and performance. For example, if an air quality monitor is dropped, the impact could damage its internal sensors, resulting in inaccurate readings.
• Improper Calibration: Calibration is crucial for ensuring the accuracy of air quality monitors. Failing to calibrate the device according to the manufacturer's guidelines or industry standards, such as those provided by OSHA, can lead to incorrect readings and potentially put people at risk.
• Neglecting Maintenance: Regular maintenance, such as cleaning or replacing filters, is essential for the proper functioning of air quality monitors. Neglecting maintenance can lead to sensor clogging, reduced sensitivity, and inaccurate readings.
• Inappropriate Placement: Air quality monitors should be placed in appropriate locations to ensure accurate readings. Placing the device in an area with poor ventilation, excessive pollutants, or interference from other devices may compromise the accuracy of its measurements.
• Tampering with Settings: Tampering with the settings of an air quality monitor without proper knowledge can affect its performance. Adjusting sensitivity levels, measurement ranges, or alarm thresholds without a thorough understanding of the device's functionality may lead to incorrect readings or failure to detect hazardous conditions.
• Ignoring Alerts: Air quality monitors often have alert systems to notify users of potential issues. Ignoring or disabling these alerts without addressing the underlying problem can lead to prolonged exposure to harmful pollutants or unsafe conditions.

To prevent monitor abuse, it is essential to follow the manufacturer's instructions and industry guidelines, such as those provided by OSHA. Proper training, regular maintenance, and responsible handling of air quality monitors can help ensure their accuracy and reliability, ultimately contributing to a safer and healthier environment for all.

Real-time monitoring

In the context of OSHA standards, real-time monitoring can help businesses identify and address indoor air quality issues. OSHA guidelines cover various aspects of indoor air quality, including temperature controls, humidity, ventilation, and smoking. Businesses can utilise real-time monitoring tools to ensure they meet these standards and provide a safe environment for their employees and patrons.

Furthermore, real-time monitoring is crucial in industries where workers are exposed to hazardous gases. OSHA has released guidelines for calibrating and testing portable gas monitors, which are frequently used in confined spaces. By conducting regular calibration and testing, employers can ensure the accuracy of these monitors and protect their workers from toxic gases and oxygen-deficient or combustible atmospheres.

Overall, real-time monitoring plays a vital role in maintaining air quality standards and ensuring the health and safety of individuals, whether in indoor environments or industrial settings.

Calibration and bump testing

Calibration

Calibration is the process of adjusting an instrument's readings to align with known concentrations of a test gas. This procedure is crucial for the accurate detection of hazardous gases and is recommended by the Occupational Safety and Health Administration (OSHA). While OSHA doesn't specify calibration frequency, it advises following the manufacturer's recommendations. The International Safety Equipment Association (ISEA) suggests verifying sensor accuracy before each day's use. Calibration should also be performed after any event that might affect the instrument's accuracy, such as damage or prolonged inactivity.

The calibration process involves exposing the instrument to a known concentration of test gas and comparing the sensor's response to the expected outcome. This verification ensures that the instrument's alarms function properly and provides an accurate reference point for future measurements. Calibration is particularly important for gas detectors used in confined spaces, as they play a vital role in worker safety.

Calibration Drift

Calibration drift is a common issue with gas monitors over time. It occurs when the instrument's reference point shifts, resulting in unreliable readings. This drift is caused by various factors, including sensor degradation, exposure to extreme environmental conditions, sensor poisoning, and physical damage to the instrument. Regular calibration checks or full calibrations are necessary to correct calibration drift and ensure the instrument's accuracy.

Bump Testing

Bump testing, also known as a function check or calibration check, is a qualitative test to ensure the functionality of the instrument. During a bump test, a challenge gas is passed over the sensor(s) to activate all alarm settings. While bump testing does not measure the instrument's accuracy, it confirms that gas can reach the sensor(s) and that the alarms are functional. Bump tests are typically recommended before each use and serve as a crucial indicator of when a full calibration is required.

Calibration Frequency

The frequency of calibration depends on the specific type of gas monitor and the usage environment. While OSHA doesn't provide specific guidelines, it emphasizes the importance of regular calibration to maintain instrument accuracy and worker safety. Most manufacturers recommend bump testing before each day's use and calibrating monthly or every six months. Calibration should also be performed after any event that might impact the instrument's accuracy or performance.

Best Practices

To ensure effective calibration and bump testing, it is essential to follow the manufacturer's guidelines and standard procedures. Calibration should be conducted in environmental conditions similar to the actual workplace conditions to account for factors like temperature and humidity. Maintaining detailed calibration records for each instrument is crucial, as it helps identify instruments with a history of maintenance issues or erratic readings.

In summary, calibration and bump testing are vital procedures for ensuring the accuracy and reliability of air quality monitors, especially in industrial settings where worker safety is paramount. By following recommended practices and manufacturer guidelines, organizations can maintain proper instrument functionality and protect their workers from hazardous gases and airborne pollutants.

Frequently asked questions