3
when connected to a compressor rated at 1,800 standard
cubic feet per minute (scfm). The compressor passed air
through a V-bank filter setup with a MERV 16 filter and
was connected to the DCAC with approximately 40 ft of
6-in (15.24-cm) tubing. Airflow (scfm) to the DCAC from
the compressor was measured continuously during DCAC
operation using a Veltron II transmitter connected to an
ACCU-flo Flow Station (Air Monitor, Santa Rosa, CA).
Both the blower and associated filter bank were located
at the back of the test entry, as shown in Figure 3. The
DCAC setup and location were held consistent throughout
all testing.
Temperature and relative humidity in the test section
were measured continuously during the test using a Vaisala
HM70 HUMICAP ® (Vantaa, Finland).
DCAC Air Velocity Profile
To determine the air velocity profile of the DCAC and
measure DPM concentration, a metal grid, measuring
approximately 3 ft × 3 ft ,was hung 15 inches below and
parallel with the plenum. The 15-inch distance was used to
simulate the distance of the miner’s breathing zone below
the ANFO loader roof, as seen in Figure 2. If the DCAC
was installed directly onto the canopy of an average ANFO
loader, the top of the DCAC would be approximately
79 inches from the bottom of the basket. The average height
of a male is 70 inches, and the breathing zone is 6 inches
below the top of the head (Grasgruber et al. 2016, CDC
2016). Therefore, the breathing zone of an average height
male would be about 15 inches from the DCAC. The mea-
surement grid contained 3-inch (7.62-cm) squares num-
bering 9 to a side. Each square was uniquely identified by
numbers from front to back from 1 to 9 (Y-axis) and then
from left to right by letters ranging from A to I (X-axis), for
a total of 81 sampling points. With the DCAC operating,
the velocity in the center of each square was measured using
a vane anemometer (Davis Instruments, Baltimore, MD)
for a period of one minute, after a 30-second stabilization
period at each point. This testing scenario was completed in
duplicate, and the averaged results are presented.
Sampling Methodology
SKC DPM cassettes (Eighty-Four, PA) with Zefon Elf
pumps were used to collect elemental carbon (EC) samples
for NIOSH Method 5040 analysis (NIOSH 2016, Birch
2003). These cassettes are used in mining for compliance
sampling and include an impactor, with a 1-μm size cut-
point, to remove the mine dust from diesel particulate mat-
ter, which is then collected on a quartz fiber filter (Noll et
al. 2005). After collecting the DPM, the quartz fiber filters
were analyzed at the Pittsburgh laboratory for EC and total
carbon (TC) via NIOSH Method 5040. The flow rate for
samplers was set at 1.7 lpm. Flow rate was calibrated using
Figure 3. Schematic of the diesel laboratory in the Experimental Mine at
NIOSH Pittsburgh
Figure 4. The canopy air curtain designed for the ANFO
loader
when connected to a compressor rated at 1,800 standard
cubic feet per minute (scfm). The compressor passed air
through a V-bank filter setup with a MERV 16 filter and
was connected to the DCAC with approximately 40 ft of
6-in (15.24-cm) tubing. Airflow (scfm) to the DCAC from
the compressor was measured continuously during DCAC
operation using a Veltron II transmitter connected to an
ACCU-flo Flow Station (Air Monitor, Santa Rosa, CA).
Both the blower and associated filter bank were located
at the back of the test entry, as shown in Figure 3. The
DCAC setup and location were held consistent throughout
all testing.
Temperature and relative humidity in the test section
were measured continuously during the test using a Vaisala
HM70 HUMICAP ® (Vantaa, Finland).
DCAC Air Velocity Profile
To determine the air velocity profile of the DCAC and
measure DPM concentration, a metal grid, measuring
approximately 3 ft × 3 ft ,was hung 15 inches below and
parallel with the plenum. The 15-inch distance was used to
simulate the distance of the miner’s breathing zone below
the ANFO loader roof, as seen in Figure 2. If the DCAC
was installed directly onto the canopy of an average ANFO
loader, the top of the DCAC would be approximately
79 inches from the bottom of the basket. The average height
of a male is 70 inches, and the breathing zone is 6 inches
below the top of the head (Grasgruber et al. 2016, CDC
2016). Therefore, the breathing zone of an average height
male would be about 15 inches from the DCAC. The mea-
surement grid contained 3-inch (7.62-cm) squares num-
bering 9 to a side. Each square was uniquely identified by
numbers from front to back from 1 to 9 (Y-axis) and then
from left to right by letters ranging from A to I (X-axis), for
a total of 81 sampling points. With the DCAC operating,
the velocity in the center of each square was measured using
a vane anemometer (Davis Instruments, Baltimore, MD)
for a period of one minute, after a 30-second stabilization
period at each point. This testing scenario was completed in
duplicate, and the averaged results are presented.
Sampling Methodology
SKC DPM cassettes (Eighty-Four, PA) with Zefon Elf
pumps were used to collect elemental carbon (EC) samples
for NIOSH Method 5040 analysis (NIOSH 2016, Birch
2003). These cassettes are used in mining for compliance
sampling and include an impactor, with a 1-μm size cut-
point, to remove the mine dust from diesel particulate mat-
ter, which is then collected on a quartz fiber filter (Noll et
al. 2005). After collecting the DPM, the quartz fiber filters
were analyzed at the Pittsburgh laboratory for EC and total
carbon (TC) via NIOSH Method 5040. The flow rate for
samplers was set at 1.7 lpm. Flow rate was calibrated using
Figure 3. Schematic of the diesel laboratory in the Experimental Mine at
NIOSH Pittsburgh
Figure 4. The canopy air curtain designed for the ANFO
loader