A Matter of Accuracy: Calibrating & Using Personal Sampling Pumps
By: Tim Turney, Contributor
According to a recent collaborative study between the World Health Organization (WHO) and the International Labor Organization (ILO), the majority of work-related deaths over a 15-year period can be attributed to respiratory and cardiovascular diseases. Air sampling pumps are crucial pieces of a kit that offer employers a tool to effectively monitor the air quality of employees’ working environment. This equipment can offer invaluable data for assessing potential health risks, provided it remains accurate and reliable, requiring regular calibration.
Importance of Proper Usage
Personal air sampling pumps are body-worn instruments that process a volume of air at a known flow rate. When paired with air sampling accessories, these pumps can be used to determine the gases, dusts and vapors that the individual is exposed to throughout their working day. As the pump is attached to the person, the sample recorded is specific and accurate to their exposure—meaning that employees with different working routines will collect samples to identify the level of risk to which they are subjected.
Different types of pollutants require specific media for accurate collection. This could be a filter for sampling dusts or a charcoal tube for sampling vapors. Understanding the nature of the target pollutants and selecting the appropriate media ensures that the pump captures a representative sample. Once the dust, gases or vapors are sampled onto a medium, this is sent to a laboratory where analytical tools are used to calculate the level of exposure; this can then be used to determine the health risks associated.
Factors such as flow rate, sampling duration and pump compatibility with target contaminants must be carefully considered. Failure to adhere to proper usage guidelines can lead to inaccurate measurements, compromising the effectiveness of air quality assessments.
Components & Types of Air Sampling Pumps
Air sampling pumps consist of various components, including a pump mechanism, flow control devices and sample collection media. Different types of pumps exist, such as personal pumps for individual exposure assessments and area pumps for broader environmental monitoring.
Understanding the components and functionalities of air sampling pumps is vital for their proper usage. Users should be familiar with the pump’s operational settings; how to assemble and disassemble components used for sampling (referred to as the sample train); and the appropriate calibration procedures.
Calibrating Air Sampling Pumps
Calibrating personal air sampling pumps is the most critical step in ensuring consistent accuracy and reliability throughout the product’s lifetime. Calibration involves adjusting the pump to deliver a precise and consistent flow rate. The calibration process typically includes the following steps:
- Preparation: Before calibration, ensure that the pump is clean and charged, and all components are in good condition.
- Selection of Calibration Equipment: Use calibrated flowmeters to measure the pump’s flow rate accurately. After the sample has been taken, flow should not deviate by more than 5% compared to the flow set before the sample was taken.
- Calibration Setup: Connect the air sampling pump to the calibration train following the manufacturer’s guidelines, ensuring all components are attached properly and without loose or leaking connections. If sampling heads or tunes have ‘O’ rings in them for sealing, check they are in place and not damaged.
- Adjustment of Flow Rate: Check manufacturers’ guidance for pumps; some older pumps require a warmup period where they need running before calibration. Following operating instructions for the calibrator, adjust the flow rate on the pump until the appropriate flow rate is displayed.
- Post Measurement Verification: After the air sampling is complete, verify the pump’s flow rate. Flow should not have deviated by more than 5% from the pre-sample value.
- Transporting Samples: Recorded samples should be delivered to a laboratory in a sealed bag for analysis to reduce the risk of contamination, with nullifies the accuracy of the sample.
- Periodic Calibration: Regular calibration is crucial to account for pump performance changes over time. Establish a calibration schedule and adhere to it to maintain the pump’s accuracy.
The selected flow measurement equipment used to calibrate pumps should have a known and traceable calibration standard. There are primary and secondary types of flowmeters. Secondary flowmeters, such as rotameters, can be used in the field but they can be less accurate. They must be calibrated against a primary standard on a regular basis.
Common Challenges and Best Practices
Despite following proper usage and calibration procedures, personal sampling pumps and items in the sampling may need maintenance and care.
- Regularly Maintain: Perform routine maintenance to keep the pump in optimal condition. Pumps are mechanical devices with valves and other items which can wear. Note the pump service interval and maintain the pump following the manufacturer’s recommendations.
- Consider the Working Environment: Be aware of ambient conditions during sampling, as variations in temperature and altitude can affect pump performance. Check any manufacturers’ guidelines for any flow corrections you might need to make, to ensure the volume of air sampled is correct.
- Refer to Previous Records: Keep detailed records of calibration occurrences; any resulting maintenance required; and any anomalies that appear during the first test after calibration.
- Complete Training: Ensure that individuals using personal air sampling pumps are adequately trained in proper usage, calibration and troubleshooting. For example, ensure sample train items are cleaned, such as cyclone sampling heads, and items like tubing are checked for damage.
Personal air sampling pumps are important tools to quantify employee exposure, but only if they are used correctly and calibrated properly can they deliver accurate, reliable samples. Employees in high-risk environments should carry out regular calibration on air sampling pumps, so that when they are needed to assess dangerous working environments, the pumps are in working order. Simply maintaining this practice can and will contribute to the reduction of workers suffering from long latency respiratory illnesses and diseases.
Tim Turney is Global Marketing Manager and an occupational hygiene and environmental expert at Casella. www.casellasolutions.com
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