Evaluation of IOM Personal Sampler at Different Flow Rates

Abstract

The Institute of Occupational Medicine (IOM) personal sampler is usually operated at a flow rate of 2.0 L/min, the rate at which it was designed and calibrated, for sampling the inhalable mass fraction of airborne particles in occupational environments. In an environment of low aerosol concentrations only small amounts of material are collected, and that may not be sufficient for analysis. Recently, a new sampling pump with a flow rate up to 15 L/min became available for personal samplers, with the potential of operating at higher flow rates. The flow rate of a Leland Legacy sampling pump, which operates at high flow rates, was evaluated and calibrated, and its maximum flow was found to be 10.6 L/min. IOM samplers were placed on a mannequin, and sampling was conducted in a large aerosol wind tunnel at wind speeds of 0.56 and 2.22 m/s. Monodisperse aerosols of oleic acid tagged with sodium fluorescein in the size range of 2 to 100 microm were used in the test. The IOM samplers were operated at flow rates of 2.0 and 10.6 L/min. Results showed that the IOM samplers mounted in the front of the mannequin had a higher sampling efficiency than those mounted at the side and back, regardless of the wind speed and flow rate. For the wind speed of 0.56 m/s, the direction-averaged (the average value of all orientations facing the wind direction) sampling efficiency of the samplers operated at 2.0 L/min was slightly higher than that of 10.6 L/min. For the wind speed of 2.22 m/s, the sampling efficiencies at both flow rates were similar for particles < 60 microm. The results also show that the IOM's sampling efficiency at these two different flow rates follows the inhalable mass curve for particles in the size range of 2 to 20 microm. The test results indicate that the IOM sampler can be used at higher flow rates.

Should we be concerned about composite (nano-)dust?

“…Before the experiment, the glass-fiber filters fixed in the cassette were carefully weighed with a microbalance (ME, Sartorius, Göt-tingen, Germany). The air flow of the pump (4 l/min) was calibrated with the Gilibrator-2 (Gilian, Sensidyne, Schauenburg International GmbH, Mülheim, Germany) [14].…”

Assessment of increased sampling pump flow rates in a disposable, inhalable aerosol sampler

“…[15] Anthony et al [17] reported that computerized simulations of the new sampler operating at a flow rate of 10 L/min also achieved the targeted sampler efficiency. Zhou et al [16] researched the effect of increasing the flow rate of an IOM sampler from 2 L/min to 10.6 L/min in order to evaluate if the performance of the sampler was similar at both flow rates. Using a wind tunnel, they evaluated the sampling efficiency of the IOM sampler as it pertained to particle size, wind speed, and wind direction.…”

“…Using a wind tunnel, they evaluated the sampling efficiency of the IOM sampler as it pertained to particle size, wind speed, and wind direction. [16] Zhou and his colleagues concluded that at a low wind speed of 0.56 m/s, the IOM could maintain its original collection capabilities while operated at a higher flow rate. They found that the direction-averaged sampling efficiencies for both flow rates had a similar trend, but there was a slightly lower efficiency for the 10.6 L/min sampling flow rate as compared with that of the 2 L/min flow rate.…”

A wind tunnel test of newly developed personal bioaerosol samplers

“…Figure 3 shows the schematic diagram of the Lovelace Respiratory Research Institute (LRRI) large wind tunnel facility employed in this research. This wind tunnel facility has been used in many sampler performance studies for different stationary and personal aerosol samplers (Cheng et al, 2004;Irshad et al, 2006;Zhou and Cheng, 2010), and the results acquired have shown that this wind tunnel can provide reliable experimental data for general aerosol sampler evaluation studies. The LRRI large wind tunnel consists of an 11-m circular duct (1.8 m in diameter), an array of industrial gas mixing blenders (Blender Products, Inc. Denver, CO), a honeycomb flow straightener, a 4.3 m (L) Â 3.7 m (W) Â 3.6 m (H) test chamber, a outflow HEPA filter bank, and a 50-hp motor (Marathon Electric, Wausau, WI).…”