[Code of Federal Regulations]
[Title 40, Volume 5]
[Revised as of July 1, 2004]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR53.42]
[Page 49-50]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 53_AMBIENT AIR MONITORING REFERENCE AND EQUIVALENT METHODS--Table of Contents
Subpart A_General Provisions
Sec. 53.42 Generation of test atmospheres for wind tunnel tests.
(a) A vibrating orifice aerosol generator shall be used to produce
monodispersed liquid particles of oleic acid tagged with uranine dye and
monodispersed solid particles of ammonium fluoroscein with equivalent
aerodynamic diameters as specified in table D-2. The geometric standard
deviation for each particle size and type generated shall not exceed 1.1
(for primary particles) and the proportion of multiplets (doublets and
triplets) in a test particle atmosphere shall not exceed 10 percent. The
particle delivery system shall consist of a blower system and a wind
tunnel having a test section of sufficiently large cross-sectional area
such that the test sampler, or portion thereof, as installed in the test
section for testing, blocks no more than 15 percent of that area. To be
acceptable, the blower system must be capable of achieving uniform wind
speeds at the speeds specified in table D-2.
Table D-2--Particle Sizes and Wind Speeds for Sampling Effectiveness
Tests
------------------------------------------------------------------------
Wind speed (km/hr)
Particle size ([mu]m) a -------------------------------------
2 8 24
------------------------------------------------------------------------
30.5........ l l l
50.5........ l l l
70.5........ l l l
90.5........ l l l
100.5....... l l l
110.5....... l l l
131.0....... l l l
151.0....... l l l
201.0....... l l l
251.0....... l l/s l/s
------------------------------------------------------------------------
a&thnsp[gE] Mass median aerodynamic diameter.
l = liquid particle.
s=solid particle.
Number of liquid particle test points (minimum of 3 replicates for each
combination of particle size and wind speed): 90.
Number of solid particle test points (minimum of 3 replicates for each
combination of particle size and wind speed): 6.
Total number of test points: 96.
(b) The size of the test particles delivered to the test section of
the wind tunnel shall be established using the operating parameters of
the vibrating orifice aerosol generator and shall be verified during the
tests by microscopic examination of samples of the particles collected
on glass slides or other suitable substrates. When sizing liquid
particles on glass slides, the slides should be pretreated with an
oleophobic surfactant and an appropriate flattening factor shall be used
in the calculation of aerodynamic diameter. The particle size, as
established by the operating parameters of the vibrating orifice aerosol
generator, shall be within the tolerance specified in table D-2. The
precision of the particle size verification technique shall be 0.5 [mu]m
or better, and particle size determined by the verification technique
shall not differ by more than 0.5 [mu]m or 10 percent, whichever is
higher, from that established by the operating parameters of the
vibrating orifice aerosol generator.
(c) The population of multiplets in a test particle atmosphere shall
be determined during the tests and shall not exceed 10 percent. Solid
particles shall be checked for dryness and evidence of breakage or
agglomeration during the microscopic examination. If the solid particles
in a test atmosphere are wet or show evidence of significant breakage or
agglomeration ([mu]5 percent), the solid particle test atmosphere is
unacceptable for purposes of these tests.
(d) The concentration of particles in the wind tunnel is not
critical. However, the cross-sectional uniformity of the particle
concentration in the sampling zone of the test section shall be
[[Page 50]]
established during the tests using isokinetic samplers. An array of not
less than five evenly spaced isokinetic samplers shall be used to
determine the particle concentration uniformity in the sampling zone. If
the particle concentration measured by any single isokinetic sampler in
the sampling zone differs by more than 10 percent from the mean
concentration, the particle delivery system is unacceptable in terms of
uniformity of particle concentration. The sampling zone shall be a
rectangular area having a horizontal dimension not less than 1.2 times
the width of the test sampler at its inlet opening and a vertical
dimension not less than 25 centimeters. The sampling zone is an area in
the test section of the wind tunnel that is horizontally and vertically
symmetrical with respect to the test sampler inlet opening.
(e) The wind speed in the wind tunnel shall be determined during the
tests using an appropriate technique capable of a precision of 5 percent
or better (e.g., hot-wire anemometry). The mean wind speed in the test
section of the wind tunnel during the tests shall be within 10 percent
of the value specified in table D-2. The wind speed measured at any test
point in the test section shall not differ by more than 10 percent from
the mean wind speed in the test section. The turbulence intensity
(longitudinal component and macroscale) in the test section shall be
determined during the tests using an appropriate technique (e.g., hot-
wire anemometry).
(f) The accuracy of all flow measurements used to calculate the test
atmosphere concentrations and the test results shall be documented to be
within 2 percent, referenced to a primary
standard. Any flow measurement corrections shall be clearly shown. All
flow measurements shall be given in actual volumetric units.
(g) Schematic drawings of the particle delivery system (wind tunnel
and blower system) and other information showing complete procedural
details of the test atmosphere generation, verification, and delivery
techniques shall be submitted to EPA. All pertinent calculations shall
be clearly presented.