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As NIOSH point out in the manual of analytical methods (NMAM)¹, industrial hygiene methods are geared towards measuring personal exposure, which for the last six decades has typically meant deploying a personal air sampling pump. The NMAM has no fewer than 220 references to the pump and details how the basics of sampling with a pump haven’t fundamentally changed much in those 60 years. In recent years, lithium-Ion batteries and Bluetooth® connectivity are new technological developments, in addition, there have been huge advancements in digital flow calibrators that improve Industrial Hygienist’s productivity and increase the likely successful outcome of a campaign. Air sampling pumps are regularly used in monitoring activity, but there are still a number of dos and don’ts that act as a worthy reminder for effective monitoring. There is lots of guidance on using pumps, here we consider some of these, but also some lesser-known issues that can be considered.
Safety. Many pumps come intrinsically safe (IS) rated as standard but it is worth double-checking that your pumps IS rating is still appropriate for your facility to avoid any invaluable or misleading readings.
Design. The size, weight, and convenience of the pump are all very important elements in its design. It should allow freedom of movement, be unobtrusive, robust, and not prone to leakage. There is anecdotal evidence from the pharmaceutical industry, where workers, women, in particular, find the burden of a 1lb pump just too much. If sampling for vapors and gases, do consider a smaller, lightweight low flow pump (0.05-1L), which is likely to be more acceptable than a medium flow pump (1-5L) equipped with a low flow adaptor.
When using a sorbent tube, managers need to check that the smaller (backup) section is nearer to the pump and that is positioned vertically to prevent a premature breakthrough. Most low flow pumps can handle the pressure drops of available sorbent tubes without problems, except that the nominal flow rate may decrease for certain models.
Calibration. All pumps should be calibrated with representative sampling media prior to use and it is good practice to check the pump calibration before and after use each day. Monitoring equipment must be calibrated in accordance with the ISO quality standards and regular maintenance will maximise the life of your equipment while avoiding unplanned repair costs.
Safety Standards. Don’t forget to check that your pump meets the latest standard i.e. ISO 13137² (an independent market report from INRS (France) is expected later this year). Failure to adhere to standards will put employees in the line of fire, increasing their risk of safety fines and absence costs affecting business finance.
Pulsation. If you are using a cyclone don’t assume that your pump has sufficiently low pulsation, which the ISO standard states shall not exceed 10% of the flow rate. A large pulsation value means that the size cut performance of cyclones used can be affected because their performance is flow rate dependent. Consequently, pumps that generate significant pulsation will collect smaller samples, meaning there is less data to analyse.³
Pump usage. However new your air-sampling pump is, health and safety managers must ensure that they check the pump has not exceeded its recommended run time between services, typically 2000-3000 hours.
Pumps are likely to be around for many years to come and your current 10-year-old pump may have had two new mechanisms and three battery packs and still be as good as new. Nevertheless, the latest generation of air-sampling increases efficiency in monitoring activity. The latest generation of Bluetooth® enabled pumps and flow calibrators can automate the calibration process and save valuable time, increasing confidence in the calibration results that can be saved and/or emailed for inclusion in a report.
The last generation of air sampling means that pulsation, once tested in a laboratory, can now be checked in the field at the same time as a normal flow rate calibration, through a newly introduced airflow calibrator equipped with Bluetooth®. When deployed, the pump can also be interrogated remotely from a discrete distance meaning that the worker does not have to be disturbed and the Industrial Hygienist can have more confidence that they will get a valid sample and reliable data.
The helpful do’s and don’ts of air sampling enable health and safety managers to ensure all air sampling equipment is being used appropriately while adhering to safety standards. These simple, yet effective, steps will keep employees protected throughout the working day by ensuring air-sampling pumps are accurately identifying hazardous amounts of fumes, dust, and gases that increase the risk of long-term damage.
NIOSH Manual of Analytical Methods (5th Edition)
ISO 13137:2013 Workplace Atmospheres: Pumps for personal sampling of chemical and biological agents: Requirements and test methods.
Anderson et al 1971, Lamonica and Treaftis, 1972, Caplan et al 1973, Blachman and Lippmann 1974, McCawley and Roder, 1975.