Section 4: Particulate Matter Sampling
Airmetrics
33
filter came.
3.
Use the cassette separator (P/N 600-007) to remove the top half of the filter
cassette.
4.
Using tweezers, carefully remove the exposed filter from the filter cassette and
place it into its original petri slide, replacing the petri slide lid when finished.
(Be sure to replace the filter support screen in the filter cassette assembly ).
5.
Remove the old ID tag from the filter holder assembly base and discard.
(Recheck this n umber to be sure it matches the number o n the petri slide.)
E
RROR
C
ONDITIONS
Low Battery Indicator ON
Should the Low Battery Indicator be ON at the end of a sampling period, check the
Elapsed Tim e Totalizer to determ ine the length of time the sampler ran before
shutting o ff. If the time is short (
e.g.
, only 2 hours out of a programmed 8 or 10
hours), perhaps the battery was not completely charged or is failing to hold a
charge. Note the battery number and, after recharging in the lab, observe
perform ance in th e next sam pling perio d. If the batter y fails again , it is most like ly
defective and should be replaced.
If a different battery performs in the same manner after shown to be fully charged,
the pum p moto r is perhap s drawin g more current tha n it should . If possible, in stall
a pump from another sampler. If this solves the problem, the previous pump motor
is likely defective and should be replaced. If the problem continues, a more serious
fault is occurring wh ich should be refe rred to Airme trics (see Appen dix D).
Low Flow Indicator ON
Should the Low Flow Indicator be found ON at the end of sam pling period, first
check the Elapsed Time Totalizer to determine the length of time the sampler ran
before shutting off. The possible causes for low flow are:
!
Low Battery:
Althoug h pow er did not fa ll to the 10.3 V low er limit that w ould
shut down the system, the pump may not have been receiving enough voltage
to maintain the desired air flow.
Airmetrics MiniVol Users Guide
34
Airmetrics
!
Air Restriction:
If the battery is sound, the problem may be due to a
restriction in the air inlet, filter holder, or tubing. Check for crimps or other
possible restrictions. Also, a broken or loose tubing fitting on the outlet side of
the pump could cause a low flow condition. It is also possible for excessive
moisture on the filter (rain, condensation) to cause enough flow resistance for
the Low Flow Indicator to come on.
!
Pump Malfunction:
The low flow condition could be the result of decreased
pump efficiency, which is usually caused by damaged or contaminated pump
head co mpon ents (valve s, diaphra gms). C heck to se e if the pum p can m aintain
a free (unrestricted) airflow rate of at least 5 lpm. If not, see Section 7 for
pump maintenanc e instructions.
!
NOTE
: The Low Flow Threshold Indicator normally lights whenever the
sampler is attached to a power source but is not operating.
Overriding Low Flow/Low B attery Indicators
When Low Flow and Low Battery Indicator lights are on, the system can be
restarted b y pressing the Rese t Switch. T he system will usua lly run eno ugh to
perform a brief field inspection and to obtain final flow rates. Pressing and holding
the switch provides continuo us overrid e of the fau lt circuit.
