Section 4: Particulate Matter Sampling
Airmetrics
29
A single AA battery on the circuit board operates the Programmable Timer. The
lifetime for this battery is approximately six months when it is left in place on the
circuit board. Be sure to observe the correct polarity when inserting a new AA
battery into the battery comp artmen t.
Refer to Section 8 , “Troublesho oting” for additional co mmen ts on battery
functions.
Setting the Desired Sampling Time
Determine the time of the day when the sampler is to turn on and off. Program the
timer to turn the sam pler on and off at these times (see "Prog ramming the Timer"
in Section 2).
Particulate Matter Sampling Procedure
After the sampler has been assembled, adjusted, verified to be in proper working
order, and a filter loaded in the Filter A ssemb ly, the sam pler is ready to collect air
samples.
Note
: For a qu ick referen ce to the follo wing ste ps, see "P articulate
Matter Sampling Routine at Site" (Appendix C). If a gas sample is also to be
collected simultaneously, refer to Section 5, “Integrated Gas Sampling” for proper
gas sampling procedures.
1.
Carefully transport the sampler to the field site. Verify that the sampler, when
finally installed in the mounting cradle, will be positioned with the intake
upward in an unobstructed area at least 30 cm from any obstacle to air flow.
2.
Place the sampler on a firm level surface.
3.
Rem ove the c lean Pres eparator/F ilter Holde r Assem bly from the plastic
transport bag and remove the protective plastic bag under the rain cap. Attach
the assem bly to the sa mpler to p at the qu ick conn ect.
4.
Record the following information on the PM Field Data Sheet: number of the
filter, the battery ID, sampler ID, ambient temperature and pressure,
flowmeter reading, and elapsed time meter reading. (see Figure G.1 insert at
the end of this M anual).
5.
Unscrew either cap of the bale assembly bar and remove the bale assembly.
Airmetrics MiniVol Users Guide
30
Airmetrics
6.
Lift the pump and timer assembly out by the 6" diameter top cap and rest it on
the edge of the sampler casing, using the triangular mount stand. Take care not
to pull the connecting wire loose or jar the pump hose fittings. Hold the top
cap and do NOT grasp the center of the circuit board.
7.
To obtain the be ginning flow rate, p ress the ON /AUTO /OFF bu tton to start
the pump. O n the LCD display, the horizon tal bar should m ove to "ON ".
8.
If the flowmeter, w hich should be in the vertical position, indicates zero or a
very low reading, check for restrictions in the tubing, or improperly seated
screw fittings betw een the pum p and the flow meter.
9.
Using the Flow Rate Adjustment control (see Figure 3.1), set the flowmeter
flow within specifications for the project temperature and pressure conditions.
Take the reading of the flowmeter from the center of the ball. (See
Append ix A).
10. Press the ON/AUTO/OFF button twice to stop pump.
11. Press the ON/AUTO/OFF button to set the timer to "Auto" mode. The
Sampler MU ST be in “Auto” m ode before the operator leaves.
12. Place the pump and timer assembly back into the sampler body. Replace the
bale assemb ly bar.
13. Using the hoisting pole, hook the bale assembly bar and raise the sampler, as
vertically as possible, to the m ounting cradle. T his position not only m ore
easily accommodates the sampler's weight, but prevents the hook from hitting
and possibly dislodging or breaking the preseparator/filter holder assembly.
(See Figure 4.1 ).
Particulate Matter Sample Retrieval
As soon as possible after the end o f the sampling p eriod, the operator sh ould return
to the monitoring site to retrieve the exposed filter. Potential for filter damage or
changes in sample mass due to particle loss, passive deposition, or volatilization
increases if the filter is left in the sample r for extend ed period s. On the Field Da ta
Sheet record the a mbient tem perature (T
a
), barometric pressu re (P
a
), and flowmeter
