Collection efficiency of field sampling cassettes

Technical Report · Mon Dec 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/6742134· OSTI ID:6742134

Fairchild, C I; Tillery, M I; Smith, J P; Valdez, F O

Industrial hygiene particulate samples are often collected under anisokinetic sampling conditions and in crosswinds. Experiments were conducted to quantitate errors associated with sampling under these nonideal conditions. Three types of field sampling cassettes were tested to determine particle sampling efficiencies for 0, 2, and 5 m/s winds at incidence angles of 0, 90, and 180/sup 0/. Tests were conducted in a chamber in which the cassettes or filter holders were moved to generate a relative wind. Eight filter cassettes mounted symmetrically on a horizontal arm which rotated about a vertical shaft at 250 rpm were positioned so that four cassettes moved at 2 m/s and four at 5 m/s. In addition to two each of the test cassettes, two in-line filter cassettes equipped with isokinetic probes were mounted on the arm. Mass, or number of particles, collected by test cassettes and isokinetic samplers was compared to that collected by stationary filters placed near the rotating arm. Results from tests in the rotating arm chamber were checked against similar tests made in a turbulent flow wind tunnel. Sampling efficiencies were compared to theoretical values calculated from Belyaev and Levin's theory, and Davies' modification for calm air sampling. Satisfactory agreement was obtained for 5-..mu..m D/sub ae/ particles; however, considerable discrepancy was noted with larger particles. The results indicate that corrections must be made to determine concentration when particles collected under nonideal sampling conditions are larger than approx. 5-..mu..m D/sub ae/.

• Research Organization: Los Alamos Scientific Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6742134
• Report Number(s): LA-8640-MS
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AEROSOL MONITORING
AEROSOLS
AIR SAMPLERS
COLLOIDS
COMPARATIVE EVALUATIONS
DATA
DATA COMPILATION
DISPERSIONS
EQUIPMENT
ERRORS
INDUSTRIAL MEDICINE
INFORMATION
LABORATORY EQUIPMENT
MEDICINE
MONITORING
NUMERICAL DATA
PERFORMANCE TESTING
SAMPLERS
SOLS
TESTING
WIND