An aerosol generation system for the production of respirable grain dust.
Volckens-J; O'Shaughnessy-PT; Hemenway-DR
Appl Occup Environ Hyg 1998 Feb; 13(2):122-126
The ability of an acoustic aerosol generating system to produce respirable grain dust from feed oats was examined. Grain dust was generated by the abrasion of oat grains weighing 50 to 250 grams (g) in an acrylic/plastic cylinder via an oscillating air wave. The flow rate within the generator was varied from 0 to 18 liters per minute (L/min) using a rotameter. The input energy supplied to the audio speaker was controlled between 0 and 12 volts (V) by a voltage regulator. A real time aerosol monitor was used to measure grain dust concentrations. The inspirable portion of grain dust was collected on 0.8 micrometer (microm) membrane filters and analyzed gravimetrically. Dust particles were viewed using a light microscope. An eight stage cascade impactor was applied to particle size analysis. Evidence of oat grain abrasion was observed under the scanning electron microscope. At a flow rate of 12L/min, the collected grain dust had a mass median aerodynamic diameter of 1.05+/-1.86microm. At a flow rate of 12L/min, the dust generation limits were measured at oat grain masses between 120 and 190g and speaker voltages ranging from 8 to 12V. At a grain mass of 150g and an input voltage of 5.86V, the aerosol mass flux increased with increasing air flow through the cylinder, until peaking at 6L/min. Aerosol mass flux decreased with increases in air flow above 6L/min. Over a 1 hour period, the output rate of the generator increased significantly with time, as grain bolus age increased. The authors conclude that a feedback control system may be needed to combat the increased aerosol production rate with time.
NIOSH-Publication; NIOSH-Grant; Control-technology; Aerosol-generators; Aerosol-particles; Aerosol-sampling; Grain-dusts; Dust-analysis; Dust-collection; Gravimetric-analysis; Respirable-dust; Sampling-methods; Microscopic-analysis; Particle-aerodynamics; Particulate-sampling-methods; Particulate-dust; Particulates
Civil Engineering University of Vermont RM 226 Votey Bldg Burlington, VT 05405
Applied Occupational and Environmental Hygiene
University of Vermont & St Agric College, Burlington, Vermont