Section 4: Particulate Matter Sampling
Airmetrics
25
ambient con ditions. Since the den sity of air and the beha vior of the flowm eter are
functions of the ambient air temperature and atmospheric pressure, a flow rate set
point m ust be calc ulated for e ach differe nt samp ling projec t.
The sampler air flow calibration curves that are supplied with each sampler
contains the necessary information needed to determine the flowmeter set point for
a particular ambien t condition . Appen dix A co ntains the c omple te instruction s in
calculating the flow set points.
F
LOWMETER
C
ALIBRATION
The sam pler shou ld be reca librated if the flo wme ter or the pu lse dam pener is
replaced.
Presep arator /Filter H older A ssemb ly
Depending on the required particle size separation, the configuration of the
Preseparator changes. The attached Filter Holder Assembly contains a filter
cassette in which the 47mm filter is supported by a filter supp ort screen (see Figu re
4.3 for PM
10
and Figure 4.4 for PM
2.5
).
C
LEAN AND
G
REASE
I
MPACTOR
Initially, and after every seventh sample, the impactor target should be cleaned and
greased under a laboratory fume hood (preferably) or any well ventilated area
(including on-site). The cleaning frequency should be increased or decreased
depending on the ambient loadings and degree of soiling observed on the target
disk.
For Impactor cleaning procedures, see Section 7, Maintenance, "Impactor
Cleaning."
Airmetrics MiniVol Users Guide
26
Airmetrics
Figure 4.3.
PM
10
Preseparator and
Filter Holder Assembly
I
NSTALLING
F
ILTERS
This procedure should tak e place in
a laboratory or other clean area.
Contac t with and handling of all
filters should be limited to the edges
of the filters. Also, the use of non-
serrated, T eflon®-tipp ed forcep s is
strongly recom mended . Filters
should be kep t in protective petri
slides. Filters must never be bent or
folded.
1. Select a filter and remove cover
from petri slide.
2. Using forceps, install the new
filter into the filter cassette.
3. Place the filter cassette in the
filter holder.
4. Replace preseparator adapter
and screw down snugly.
5. Place an identifying tag on the
filter holder so that the ID
numb er of the filter m ounted in
the holder is known.
6. Place a clean, plastic bag over the top of the preseparator adapter inlet and
push the rain cap snugly into place over the bag.
