# Title 40

## SECTION 53.62

### 53.62 Test procedure: Full wind tunnel test.

§ 53.62 Test procedure: Full wind tunnel test.(a) *Overview.* The full wind tunnel test evaluates the
effectiveness of the candidate sampler at 2 km/hr and 24 km/hr for
aerosols of the size specified in table F-2 of this subpart (under
the heading, “Full Wind Tunnel Test”). For each wind speed, a
smooth curve is fit to the effectiveness data and corrected for the
presence of multiplets in the wind tunnel calibration aerosol. The
cutpoint diameter (Dp50) at each wind speed is then determined from
the corrected effectiveness curves. The two resultant penetration
curves are then each numerically integrated with three idealized
ambient particle size distributions to provide six estimates of
measured mass concentration. Critical parameters for these
idealized distributions are presented in table F-3 of this
subpart.

(b) *Technical definitions.* Effectiveness is the ratio
(expressed as a percentage) of the mass concentration of particles
of a specific size reaching the sampler filter or filters to the
mass concentration of particles of the same size approaching the
sampler.

(c) *Facilities and equipment required* - (1) *Wind
tunnel.* 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 the test section area. The wind tunnel
blower system must be capable of maintaining uniform wind speeds at
the 2 km/hr and 24 km/hr in the test section.

(2) *Aerosol generation system.* A vibrating orifice
aerosol generator shall be used to produce monodisperse solid
particles of ammonium fluorescein with equivalent aerodynamic
diameters as specified in table F-2 of this subpart. The geometric
standard deviation for each particle size generated shall not
exceed 1.1 (for primary particles) and the proportion of multiplets
(doublets and triplets) in all test particle atmosphere shall not
exceed 10 percent of the particle population. The aerodynamic
particle diameter, as established by the operating parameters of
the vibrating orifice aerosol generator, shall be within the
tolerance specified in table F-2 of this subpart.

(3) *Particle size verification equipment.* The size of the
test particles shall be verified during this test by use of a
suitable instrument (e.g., scanning electron microscope, optical
particle sizer, time-of-flight apparatus). The instrument must be
capable of measuring solid and liquid test particles with a size
resolution of 0.1 µm or less. The accuracy of the particle size
verification technique shall be 0.15 µm or better.

(4) *Wind speed measurement.* The wind speed in the wind
tunnel shall be determined during the tests using an appropriate
technique capable of a precision of 2 percent and an accuracy of 5
percent or better (e.g., hot-wire anemometry). For the wind speeds
specified in table F-2 of this subpart, the wind speed shall be
measured at a minimum of 12 test points in a cross-sectional area
of the test section of the wind tunnel. The mean wind speed in the
test section must be within ±10 percent of the value specified in
table F-2 of this subpart, and the variation at any test point in
the test section may not exceed 10 percent of the measured
mean.

(5) *Aerosol rake.* The cross-sectional uniformity of the
particle concentration in the sampling zone of the test section
shall be established during the tests using an array of isokinetic
samplers, referred to as a rake. Not less than five evenly spaced
isokinetic samplers shall be used to determine the particle
concentration spatial uniformity in the sampling zone. 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.

(6) *Total aerosol isokinetic sampler.* After
cross-sectional uniformity has been confirmed, a single isokinetic
sampler may be used in place of the array of isokinetic samplers
for the determination of particle mass concentration used in the
calculation of sampling effectiveness of the test sampler in
paragraph (d)(5) of this section. In this case, the array of
isokinetic samplers must be used to demonstrate particle
concentration uniformity prior to the replicate measurements of
sampling effectiveness.

(7) *Fluorometer.* A fluorometer used for quantifying
extracted aerosol mass deposits shall be set up, maintained, and
calibrated according to the manufacturer's instructions. A series
of calibration standards shall be prepared to encompass the minimum
and maximum concentrations measured during size-selective tests.
Prior to each calibration and measurement, the fluorometer shall be
zeroed using an aliquot of the same solvent used for extracting
aerosol mass deposits.

(8) *Sampler flow rate measurements.* All flow rate
measurements used to calculate the test atmosphere concentrations
and the test results must be accurate to within ±2 percent,
referenced to a NIST-traceable primary standard. Any necessary flow
rate measurement corrections shall be clearly documented. All flow
rate measurements shall be performed and reported in actual
volumetric units.

(d) *Test procedures* - (1) *Establish and verify wind
speed.* (i) Establish a wind speed specified in table F-2 of
this subpart.

(ii) Measure the wind speed at a minimum of 12 test points in a cross-sectional area of the test section of the wind tunnel using a device as described in paragraph (c)(4) of this section.

(iii) Verify that the mean wind speed in the test section of the wind tunnel during the tests is within 10 percent of the value specified in table F-2 of this subpart. 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.

(2) *Generate aerosol.* (i) Generate particles of a size
specified in table F-2 of this subpart using a vibrating orifice
aerosol generator.

(ii) Check for the presence of satellites and adjust the generator as necessary.

(iii) Calculate the physical particle size using the operating parameters of the vibrating orifice aerosol generator and record.

(iv) Determine the particle's aerodynamic diameter from the calculated physical diameter and the known density of the generated particle. The calculated aerodynamic diameter must be within the tolerance specified in table F-2 of this subpart.

(3) *Introduce particles into the wind tunnel.* Introduce
the generated particles into the wind tunnel and allow the particle
concentration to stabilize.

(4) *Verify the quality of the test aerosol.* (i) Extract a
representative sample of the aerosol from the sampling test zone
and measure the size distribution of the collected particles using
an appropriate sizing technique. If the measurement technique does
not provide a direct measure of aerodynamic diameter, the geometric
mean aerodynamic diameter of the challenge aerosol must be
calculated using the known density of the particle and the measured
mean physical diameter. The determined geometric mean aerodynamic
diameter of the test aerosol must be within 0.15 µm of the
aerodynamic diameter calculated from the operating parameters of
the vibrating orifice aerosol generator. The geometric standard
deviation of the primary particles must not exceed 1.1.

(ii) Determine the population of multiplets in the collected sample. The multiplet population of the particle test atmosphere must not exceed 10 percent of the total particle population.

(5) *Aerosol uniformity and concentration measurement.* (i)
Install an array of five or more evenly spaced isokinetic samplers
in the sampling zone (paragraph (c)(5) of this section). Collect
particles on appropriate filters over a time period such that the
relative error of the measured particle concentration is less than
5.0 percent.

(ii) Determine the quantity of material collected with each isokinetic sampler in the array using a calibrated fluorometer. Calculate and record the mass concentration for each isokinetic sampler as:

Equation 7 where: i = replicate number; j = isokinetic sampler number; Miso = mass of material collected with the isokinetic sampler; Q = isokinetic sampler volumetric flow rate; and t = sampling time.(iii) Calculate and record the mean mass concentration as:

Equation 8 where: i = replicate number; j = isokinetic sampler number; and n = total number of isokinetic samplers.(iv) Precision calculation. (A) Calculate the coefficient of variation of the mass concentration measurements as:

Equation 9 where: i = replicate number; j = isokinetic sampler number; and n = total number of isokinetic samplers.(B) If the value of CViso(i) for any replicate exceeds 10 percent, the particle concentration uniformity is unacceptable and step 5 must be repeated. If adjustment of the vibrating orifice aerosol generator or changes in the particle delivery system are necessary to achieve uniformity, steps 1 through 5 must be repeated. When an acceptable aerosol spatial uniformity is achieved, remove the array of isokinetic samplers from the wind tunnel.

(6) *Alternative measure of wind tunnel total
concentration.* If a single isokinetic sampler is used to
determine the mean aerosol concentration in the wind tunnel,
install the sampler in the wind tunnel with the sampler nozzle
centered in the sampling zone (paragraph (c)(6) of this
section).

(i) Collect particles on an appropriate filter over a time period such that the relative error of the measured concentration is less than 5.0 percent.

(ii) Determine the quantity of material collected with the isokinetic sampler using a calibrated fluorometer.

(iii) Calculate and record the mass concentration as Ciso(i) as in paragraph (d)(5)(ii) of this section.

(iv) Remove the isokinetic sampler from the wind tunnel.

(7) *Measure the aerosol with the candidate sampler.* (i)
Install the test sampler (or portion thereof) in the wind tunnel
with the sampler inlet opening centered in the sampling zone. To
meet the maximum blockage limit of paragraph (c)(1) of this section
or for convenience, part of the test sampler may be positioned
external to the wind tunnel provided that neither the geometry of
the sampler nor the length of any connecting tube or pipe is
altered. Collect particles for a time period such that the relative
error of the measured concentration is less than 5.0 percent.

(ii) Remove the test sampler from the wind tunnel.

(iii) Determine the quantity of material collected with the test sampler using a calibrated fluorometer. Calculate and record the mass concentration for each replicate as:

Equation 10 where: i = replicate number; Mcand = mass of material collected with the candidate sampler; Q = candidate sampler volumetric flow rate; and t = sampling time.(iv)(A) Calculate and record the sampling effectiveness of the candidate sampler as:

Equation 11 where: i = replicate number.(B) If a single isokinetic sampler is used for the determination of particle mass concentration, replace Ciso(i) with Ciso.

(8) *Replicate measurements and calculation of mean sampling
effectiveness.* (i) Repeat steps in paragraphs (d)(5) through
(d)(7) of this section, as appropriate, to obtain a minimum of
three valid replicate measurements of sampling effectiveness.

(ii) Calculate and record the average sampling effectiveness of the test sampler for the particle size as:

Equation 12 where: i = replicate number; and n = number of replicates.(iii) Sampling effectiveness precision. (A) Calculate and record the coefficient of variation for the replicate sampling effectiveness measurements of the test sampler as:

Equation 13 where: i = replicate number, and n = number of replicates.(B) If the value of CVE exceeds 10 percent, the test run (steps in paragraphs (d)(2) through (d)(8) of this section) must be repeated until an acceptable value is obtained.

(9) Repeat steps in paragraphs (d)(2) through (d)(8) of this section until the sampling effectiveness has been measured for all particle sizes specified in table F-2 of this subpart.

(10) Repeat steps in paragraphs (d)(1) through (d)(9) of this section until tests have been successfully conducted for both wind speeds of 2 km/hr and 24 km/hr.

(e) *Calculations* - (1) *Graphical treatment of
effectiveness data.* For each wind speed given in table F-2 of
this subpart, plot the particle average sampling effectiveness of
the candidate sampler as a function of aerodynamic particle
diameter (Dae) on semi-logarithmic graph paper where the
aerodynamic particle diameter is the particle size established by
the parameters of the VOAG in conjunction with the known particle
density. Construct a best-fit, smooth curve through the data by
extrapolating the sampling effectiveness curve through 100 percent
at an aerodynamic particle size of 0.5 µm and 0 percent at an
aerodynamic particle size of 10 µm. Correction for the presence of
multiplets shall be performed using the techniques presented by
Marple, et al (1987). This multiplet-corrected effectiveness curve
shall be used for all remaining calculations in this paragraph
(e).

(2) *Cutpoint determination.* For each wind speed determine
the sampler Dp50 cutpoint defined as the aerodynamic particle size
corresponding to 50 percent effectiveness from the multiplet
corrected smooth curve.

(3) *Expected mass concentration calculation.* For each
wind speed, calculate the estimated mass concentration measurement
for the test sampler under each particle size distribution (Tables
F-4, F-5, and F-6 of this subpart) and compare it to the mass
concentration predicted for the reference sampler as follows:

(i) Determine the value of corrected effectiveness using the best-fit, multiplet-corrected curve at each of the particle sizes specified in the first column of table F-4 of this subpart. Record each corrected effectiveness value as a decimal between 0 and 1 in column 2 of table F-4 of this subpart.

(ii) Calculate the interval estimated mass concentration measurement by multiplying the values of corrected effectiveness in column 2 by the interval mass concentration values in column 3 and enter the products in column 4 of table F-4 of this subpart.

(iii) Calculate the estimated mass concentration measurement by summing the values in column 4 and entering the total as the estimated mass concentration measurement for the test sampler at the bottom of column 4 of table F-4 of this subpart.

(iv) Calculate the estimated mass concentration ratio between the candidate method and the reference method as:

Equation 14 where: Ccand(est) = estimated mass concentration measurement for the test sampler, µg/m 3; and Cref(est) = estimated mass concentration measurement for the reference sampler, µg/m 3 (calculated for the reference sampler and specified at the bottom of column 7 of table F-4 of this subpart).(v) Repeat steps in paragraphs (e) (1) through (e)(3) of this section for tables F-5 and F-6 of this subpart.

(f) *Evaluation of test results.* The candidate method
passes the wind tunnel effectiveness test if the Rc value for each
wind speed meets the specification in table F-1 of this subpart for
each of the three particle size distributions.