Airmetrics MiniVol User manual

MiniVol
Portable Air Sampler
Operation Manual
Airmetrics
2121 Franklin Boulevard, #9
Eugene, OR 97403
U.S.A.
PHONE: [phone]
FAX: [phone]
E-mail: [e-mail]
www.airmetrics.com
Notice:
Information in this manual is subject to change without notice and does not
represent a commitment on the part of Airmetrics, which reserves the right to make
changes in construction, design, specifications, and/or procedures that may not be
reflected in this manual.
Printing History
Manual Version 1.0 - October, 1992, applies to Sampler M odels 3.x
Manual Version 1.0a - November, 1992, applies to Sampler Models 3.x
Manual Version 1.1 - June, 1993, applies to Sampler Model 4.0
Manual Version 1.1a - January, 1994, applies to Sampler M odel 4.0
Manual Version 1.2 - December, 1994, applies to Sampler Model 4.0
Manual Version 1.2a - July, 1996, applies to Sampler Model 4.1
Manual Version 4.2 - May, 1997 applies to Sampler M odel 4.2
Manual Version 4.2a - February, 1998 applies to Sampler Model 4.2
Manual Version 4.2b - December, 2000 applies to Sampler Model 4.2
Manual Version 4.2c - June, 2001 applies to Sampler M odel 4.2

Table of Contents
Airmetrics i
Table of Contents
1INTRODUCTION 1
Principles of Operation ...................................1
Particulate Matter Sampling Mode .........................2
Integrated Gas Sampling Mode ...........................3
2GETTING STARTED 5
Inspecting Components ...................................5
Charging Batteries ......................................5
Connecting Sampler Body and Battery Pack ......................6
Removing Pump and Timer Assembly .........................7
Turning the Sampler On/Off ................................8
Programming the Timer ..................................8
Setting the Real-Time Clock .............................9
Setting the On/Off Times ...............................9
Setting the Timer to “On,” “Auto,” and "Off" Modes ...........10
Checking for Leaks ....................................11
3CONTROLS AND ADJUSTMENTS 13
All Operating Modes ...................................13
Elapsed Time Totalizer ...............................13
Programmable Timer ................................13
Flowmeter .......................................13
Flow Rate Adjustment ................................13
12V Battery Power Connector ..........................14
Low Flow Threshold Indicator ..........................14
Low Flow Cutoff Indicator .............................15
Low Flow Zero & Cutoff Adjustments .....................15
Low Battery Indicator ................................16
Lo-Flow/Lo-Battery Reset Switch ........................ 16
ON/AUTO/OFF Button ...............................17
Integrated Gas Sampling Option ............................17
Solenoid Valve Output C onnectors ........................ 18
Active Solenoid Output Indicators ........................18
Manual Sequence Advance Button ........................18
Airmetrics MiniVol Users Guide
ii Airmetrics
Pulse Interval Adjustment ............................. 18
Pulse Duration Adjustment ............................ 18
Power On/Off .................................... 19
Pulse Indicator .................................... 19
Overlap Jumper ................................... 19
4PARTICULATE MATTER SAMPLING 21
Consumables ........................................ 21
Siting Requirements ................................... 21
Attaching the Mounting C radle ............................ 21
Preparing the Sampler .................................. 22
Flow Rate ....................................... 24
Flowmeter Calibration ............................... 25
Preseparator/Filter Holder Assembly ........................ 25
Clean and Grease Impactor ............................ 25
Installing Filters ................................... 26
Preparing the Battery Pack ............................... 27
Battery Charging .................................. 27
Changing/Installing Battery Pack on Sampler ................ 28
Other Battery Checks ............................... 28
Setting the Desired Sampling Time .......................... 29
Particulate Matter Sampling Procedure ....................... 29
Particulate Matter Sample Retrieval ......................... 30
Exposed Filter .................................... 32
Error Conditions .................................. 33
Low Battery Indicator ON ......................... 33
Low Flow Indicator ON ........................... 33
Overriding Low Flow /Low Battery Indicators ............. 34
5INTEGRATED GAS SAMPLING 35
Consumables ........................................ 35
Siting Requirements ................................... 35
Attaching the Mounting C radle ............................ 35
Preparing the Sampler .................................. 36
Operation Modes - Standard Mode or Overlap Mode ........... 36
Adjusting Pulse Frequency and Duration ................... 39
Pulse Interval Adjustment .......................... 40
Pulse Duration Adjustment ......................... 40
Preparing the Sampler .................................. 41
Installing Tedlar® Bags and Attaching Canisters .............. 42

Table of Contents
Airmetrics iii
Integrated Gas Sampling Procedure ..........................44
Gas Sample Retrieval ...................................45
6HARDWARE DESCRIPTION 47
Pneumatic System .....................................47
Pneumatic System Flow Schematic ....................... 47
Filter Holder Assembly ...............................47
Flowmeter .......................................47
Flow Control System ................................47
Miniature Brushless D.C. Double Acting Diaphragm Pump .......47
Electronics System .....................................49
Motherboard ......................................49
Power ..........................................49
Programmable Timer ................................49
Flow Controller C ircuit ...............................50
Elapsed Time Totalizer ...............................50
Interconnect Board ..................................50
Motherboard E lectronics S chema tic ....................... 50
Battery Pack Charger Electronics Schema tic .................50
Valve D river Board Electronics Schematic ..................50
7MAINTENANCE 51
Preseparator/Filter Holder Assembly ......................... 51
Impactor Cleaning ..................................51
Flow Control System ...................................52
Programmable Timer ...................................53
Battery Pack .........................................53
Cleaning/Inspecting Pump Valves and Diaphragms ................53
Cleaning/Inspecting Pump Head Valves ....................54
8TROUBLESHOOTING 55
Airmetrics MiniVol Users Guide
iv Airmetrics
Appendices
ASAMPLER FLOW RATE CALIBRATION 59
BGRAVIMETRIC ANALYSIS PROCEDURE 67
CQUICK REFERENCE 79
DWARRANTY POLICY 83
EREPLACING DAMAGED/DEFECTIVE COMPONENTS 85
FPARTS LIST 87
GFORMS and SCHEMATICS 105
List of Figures
Figure 2.1. Attaching Battery Pack 7
Figure 2.2. Programmable Timer 8
Figure 3.1. Sampler Contro ls and Adjustments 14
Figure 4.1. Mounted Sampler 23
Figure 4.2. Tubing Configuration for PM Sampling Mode 24
Figure 4.3. PM10 Preseparator and F ilter Holder Assem bly 26
Figure 4.4. PM2.5 Preseparator and F ilter Holder Assem bly 27
Figure 5.1. Tubing Configuration for Integrated Gas Sampling Mode 36
Figure 5.2. Installing Tedlar® Bag 42
Figure 5.3. Attaching Bag Canisters and Tubing 43
Figure 6.1. Pneumatic System Flow Schematic 48
Figure 7.1. Regreasing PM2.5 Impactor 52
Figure A.1. Portable Sampler Calibration Output 61
Figure B.1. Relative Hum idity Effects on Quartz Filters 72
Figure F.1. Main Circuit Board Parts Identification. 88
Figure F.2. Valve Driver Board Parts Identification 90
Figure F.4. Preseparator and Filter Parts Identification 94
Figure F.5. Battery Pack Parts Identification 97
Figure F.6. Integrated Gas Sampling Bag Parts Identification 99
Figure F.7. Mounting Hardware Parts Identification 101

Section 1: Introduction
Airmetrics 1
1INTRODUCTION
The MiniVol Portable Air Sampler is an ambient air sampler for particulate matter
and non-reactive gases. The patented low flow technology used in the MiniVol was
developed jointly by the U. S. Environmental Protection Agency (EPA) and the
Lane Regional A ir Pollution A uthority in an effort to address the need for portable
air pollution sampling technology.
While not a reference method sampler, the M iniVol gives results that closely
approximate reference method air quality data. Both accurate and precise, the
battery operated, lightweight MiniVol is ideal for sampling at remote sites or areas
without power. In addition, the low cost of the sampler allows a network of
MiniVols to be deployed at a fraction of the cost for a similar reference station
network.
The MiniVol features a 7-day programmable timer, a constant flow control system,
an elapsed time totalizer, rechargeable battery packs, and all-weather PVC
construction. The MiniVol can be configured to sample for just particulate matter,
just gases, or both simultaneously.
Principles of Operation
The MiniVol Portable Air Sampler is basically a pump controlled by a
programmable timer which can be set to make up to six "runs" within 24 hours or
throughout a week. When used outdoors it may be hung from a bracket mounted on
a variety of structures—utility poles, trees, fence posts, etc.
The sampler is equipped to operate from either AC or DC power sources. In the
DC operational mode, the sampler operates from a battery pack, thus making the
sampling site independent of line power. In the AC mode the battery pack is
connected to line power and mated to the sampler unit. This configuration charges
the battery while using AC power. The M iniVol comes with two battery packs to
accomplish continuous field sampling. A charged battery pack is capable of
operating the sampler for up to 24 sampling hours on a single charge.
The sampler is equipped with two "fault circuits":
Airmetrics MiniVol Users Guide
2Airmetrics
!A low battery circu it automatically shuts the sampler down should the
rechargeable lead-acid battery fail to supply sufficient voltage (below 10.3
volts) to the pump. This feature p rotects the battery which could be damaged if
used continuously at low voltage. A "low-battery" indicator lights to alert the
operator of this condition.
!A low flow circuit monitors the flow rate. Should excessive accumulation of
particulate m atter or som e restriction in the tubing cause the air flow to fall
below a specified rate, the sampler shuts down and a "low flow" indicator
lights to alert the operator.
An Elapsed Time Totalizer linked in parallel with the pump records the total time
in hours of pump operation.
PARTICULATE MATTER SAMPLING MODE
In the particulate matter (PM) sampling mode, air is drawn through a particle size
separator and then through a filter medium. Particle size separation is achieved by
impaction. Critical to the collection of the correct particle size is the correct flow
rate through the impactor. For the MiniVol, the actual volumetric flow rate must
be 5 liters per minute (5 lpm) at ambient conditions. To assure a constant 5 lpm
flow rate through the size separator at differing air temperatures and atmo spheric
pressures, the sam pler must be adjusted for each sampling project.
NOTE: The terms SIZE SEPARATOR, PRESEPARATOR and IMPA CTOR are
used interchangeably in this m anual.
Impactors are available with a 10 micron cut-point (PM10) and a 2.5 micron cut-
point (PM2.5). Operating the sampler without an impactor allows for collection of
total suspended particulate matter (TSP).
The inlet tube downstream from the filter takes the air to the twin cylinder
diaphragm pump. From the pump, air is forced through a standard flowmeter
where it is exhausted to the atmosphere inside the sampler body.
The program mable timer will automatically turn the pump o ff at the end of a
sampling period. The sampler must then be serviced and set up for the next
sampling period. Servicing includes removing the sampler from its hanging
bracket, removing the filter holder with the exposed filter inside from the sampler,

Section 1: Introduction
Airmetrics 3
and attaching a new filter holder with a fresh filter. The battery pack is also
changed at this time.
The sampling technique used by the MiniVol is a modification of the PM10
reference method described in the U. S. Code of Federal R egulations (40 CFR part
50, Appendix J). Under this criteria, a PM10 sampler must have: 1) a sam ple air
inlet system to provide particle size discrimination, 2) a flow control device
capable of maintaining a flow rate within specified limits, 3) means to measure the
flow rate during the sampling period, and 4) a timing control device capable of
starting and stopping the sampler.
The Airmetrics MiniVol Portable Air Sam pler meets all of these specifications. It
is equipped with: 1 ) an inlet impactor capable of se parating particulate matter to
#10 µm, 2) a flow control device which will maintain a specified flow rate, 3) a
flowmeter to measure the flow rate during the sampling period, 4) an elapsed time
meter, and 5) a programmable timer that starts and stops the sampler unattended.
The MiniVol's flow rate is generally less than the flow rates used by reference
method devices. The lower rate results in a greater deviation in accuracy at low
concentrations of particulate matter where precision can be lost through the
handling and weighing of a minute p articulate sample. Howeve r, at high particulate
concentrations the sampler produces results that are precise and com parable to
reference method samplers.
While the MiniV ol's sampling method is no t a reference or equivalent method, it
has proven to be an excellent indicator of absolute ambient PM10 concentrations.
Although the method used by portable PM10 sampling does not wholly conform or
comply with the reference method, the data collected by the sampler still serve as a
useful supplement to data generated by PM10 reference methods.
INTEGRATED GAS SAMPLING MODE
In the integrated gas sampling mode, the sampler can accommodate one or two bag
modules. The bags may be filled one at a time or simultaneously within a
programmable period. There are two circuits which control the gas sampling:
1. A tuneable intervalometer, or pulse circuit, determines the rate at which a bag
is filled. The circuit sends an electronic pulse to open a solenoid on the valve
Airmetrics MiniVol Users Guide
4Airmetrics
driver board. The duration of each pulse can be adjusted from approxim ately
50 to 750 milliseconds. The pulses can also be adjusted for frequency, from
one pulse every 15 seconds to continuously on.
2. A bag sequencer determines which of the two bags is being filled during any
programmed inte rval.
While the bags that are supplied with the samplers are made of relatively non-
reactive Tedlar® (polyvinyl fluoride), other parts of the air path are made of PVC,
polyethylene, silicone rubber, and other substances that are more reactive.
Consequently, you should not use the MiniVol to collect gas samples that are to be
analyzed for reactive gases like ozone or sulfur dioxide.
In the gas sampling mode, the air that is used to fill the bags is diverted from the
normal air path just before the air is vented into the sampler case—at the end of the
air path. Because of this, you may simultaneously collect a PM sample (the filter
holder is situated at the beginning of the air path) while collecting a gas sample.

Section 2: Getting Started
Airmetrics 5
2GETTING STARTED
Inspecting Components
When purchased, a standard MiniVol comes packed in two plastic carrying cases,
one containing two battery packs and a transformer, the other containing the
sampler and two preseparator/filter holder assem blies. A m ounting cradle is
shipped outside of the carrying boxes. Each sampler includes:
!1 pump module
!2 preseparator/filter holder assemblies
!2 battery packs
!1 18-volt transformer
!2 plastic carrying cases
!1 mounting cradle
If you ordered the Integrated Gas Sampling option, you will also receive:
!1 valve driver board (pre-installed on back of main circuit board)
!4 collection canisters, each with a 6-liter Tedlar® bag
!1 24-inch bale bar with removable end caps
!1 special bale handle
Every order also includes an Operation Manual and a packet of spare parts.
On receipt, visually inspect the contents of the cases to account for all components.
Compare the equipment delivered with the enclosed packing slip. Notify Airmetrics
of any missing or damaged equipment (see Appendix D).
Charging Batteries
1. Connect the charging plug of the transformer to the charging jack on the first
battery pack.
2. Plug the transformer into a fused AC outlet.
Airmetrics MiniVol Users Guide
6Airmetrics
NOTE: A Switching AC Adaptor is sup plied with a new sampler. This
universal transformer/adaptor is rated for 100-240 VAC, 50-60 Hz, and
features a 3-pole plug. The user may need to purchase a standard computer
power cord with local plug configuration to connect the tran sformer to a wall
socket for battery recharge.
3. The green LED on the top of the battery will light indicating that the battery is
being charged. W hen this light goes out, the battery is charged but continues to
receive a “trickle” charge as long as it is plugged into the charging
transformer. A fully discharged battery requires at least 18 hours to be
completely recharged.
4. If the battery will be used frequently, leave it plugged into the charging
transformer until its next use. Leaving the battery plugged in allows it to
receive a trickle charge maintaining the battery in a fully charged state. DO
NOT, however, store the battery for extended periods of time while plugged
into the charging transformer.
!The charging LED (green) should light briefly even if the battery is already
fully charged. If the charging LED on the battery fails to light, either the LED
is faulty or the charger is defective (see "Troubleshooting" sec tion).
!The batteries supplied with the sampler are of the lead-acid type. Since these
batteries may vent hydrogen gas while charging, they must be charged in a
well-ventilated area so that the hydrogen gas does not build to an explosive
concentration.
Connecting Sampler Body and Battery Pack
1. Remove the packing foam from the bottom of the sampler body.
2. Lift the sampler over the battery pack and carefully insert the banana pins
extending from the sampler bottom into the sockets on the top of the battery
pack. The pins are unevenly spaced and can fit only one way—the pin closest
to a latch on the sampler body inserts into the odd colored receptacle on
the battery pack (see Figure 2.1).
3. Clamp the two latches.

Section 2: Getting Started
Airmetrics 7
Figure 2.1. Attaching Battery Pack
Removing Pump and Timer Assembly
The bale assembly bar secures the 6" diameter top cap to the sampler body. To
remove the pump and timer assembly from inside the sampler body:
1. Lift the pump and timer assembly out holding the 6" diameter top cap, taking
care not to pull the connecting wire loose or jar the pump hose fittings.
2. Since the short connecting wire does not allow the assembly to be removed
from the sampler body beyond a few inches, rest the assembly on the edge of
the sampler casing by using the triangular mount stand. Leave the battery
attached to the sampler to stabilize the unit, and hold the assembly by the top
cap. Do NOT grasp the circuit board.
Airmetrics MiniVol Users Guide
8Airmetrics
Figure 2.2. Programmable Timer
L
Turning the Sampler On/Off
The ON/AUTO/OFF button on the
Programmable Timer allows the
operator to manually turn the
sampler on or off (or to place it in
the "Auto" mode in which it is
controlled by programmed on/off
sequences). As the ON/AUTO/OFF
button is pressed, a bar at the lower
edge of the LCD display moves
horizontally over the words "On",
"Auto" and "Off" which are printed
on the timer case (see Figure 2.2).
With the sampler attached to a
charged battery pack, press the
ON/AUTO/OFF button until the bar
is above the "On" legend. The red
power indicator (to the right of the
ON/AUTO /OFF button) should
light and the pump motor should
start.
If the Timer display does not respond, check the single A A battery on the circuit
board. Removing the battery resets the timer and clears the display.
While the sampler is running, press the ON/A UTO/OFF b utton, until the bar is
over the O FF legend. The power indicator light will go off and the pump w ill
stop running.
Programming the Timer
The Programmable Timer can be set to run up to six on/off cycles within a 24 hour
period, as well as to run for separate time periods on separate days within a 7-day
period. To set the timer, first set the real-time clock to establish the correct time
frame in which the cycles are to run. Next, enter the on/off times at which the
programmed cycles are to begin and end. Finally, set the timer to "Auto" mode.

Section 2: Getting Started
Airmetrics 9
L
Refer to Figure 2.2 when performing the following procedures.
SETTING THE REAL-TIME CLOCK
1. DAY SET: Hold dow n the CLOCK button and press the WEE K button until
the correct day appears at the top of the display.
2. TIME SET (Hour): Hold down the CLOCK button and press the HOUR
button until the display indicates the correct hour. You may have to cycle
through the hours twice to obtain the proper AM or PM (on the left side of the
display). Seconds will automatically reset to zero.
3. TIME SET (Minutes): Hold dow n the CLOCK button and press the M IN
button until the display indicates the correct m inutes. Seconds w ill
automatically reset to zero.
SETTING THE ON/OFF TIMES
1. Press the PROG button once. 1ON will appear near the lower left corner of the
display indicating that the power-on time for the first cycle is ready to be
programmed.
2. Press the HOUR and MIN buttons to enter the power-on time for the first
cycle.
3. Press the WEEK button to select the desired day. The days appear along the
top of the display. Continuou sly pressing the WEEK button will sequentially
display "Mo Tu We Th Fr Sa Su", "Mo", "Tu", "We", "Th", "Fr", "Sa",
"Su", "M o Tu W e Th Fr", "Sa Su" and finally back to
"Mo Tu We Th Fr Sa Su". When more than one day is displayed, these days
will all have the same power-on time.
4. After you have entered the power-on time and date for the first cycle, press the
PROG button. 1OFF now appe ars on the display to indicate that the power-off
time for the first cycle is ready to be program med. Repeat steps 2 and 3 to
enter the desired power-off time.
The power-off tim e does not have to occur on the same day as th e on time. In this
way, sampling may start on one day and end on the next day.
Airmetrics MiniVol Users Guide
10 Airmetrics
L
5. Press the PROG button again. 2ON appears on the display to indicate that the
second power-on time is ready to be programmed. Repeat steps 2 to 4 to enter
the remaining power-on/power-off times (up to 6 on/off times).
6. Press the PROG button to step through the times you entered to make sure
they are correct.
Press the RST/RCL button to disable (ReSeT) or reactivate (ReCalL) any time
entries. When you disable a particular power-on/off entry, four dashes w ill
appear instead of the time. When you reactivate an entry, it will return to the
values that were set before you perform ed a reset.
Be sure to clear all unwanted time entries prior to sampling in the AUTO mode.
Both ON and OFF entries need to be disabled for the unwanted programs to be
inactive.
7. Press the CLOCK button to return to the real-time clock display.
8. Press the ON/AUTO/OFF button until the bar is positioned above the "OFF"
legend.
SETTING THE TIMER TO “ON,” “AUTO,” AND "OFF"MODES
The ON/AU TO/O FF button is used to manually turn the sampler on or off, or to
place it in the "Auto" mode. A bar on the lower edge of the LCD display moves
from "Off" to "Auto" to "On" as the button is pressed. In the "Auto" mode the
sampler is controlled by the programmed on/off sequences.
!To manually turn the sampler ON, press the ON/AUTO/OFF button until the
bar on the lower edge of the display is above the "ON" legend. The pum p will
start and the power indicator w ill light.
!To manually turn the sampler OFF, press the ON/AUTO/OFF button until the
bar is above the "OFF" legend.
!To set the timer to "A UTO" mode in which the sam pler will be automatically
controlled by programmed sequences, first turn the sampler OFF. Then press
the ON/AUTO/OFF button until the bar is above the "AUTO" legend.

Section 2: Getting Started
Airmetrics 11
Checking for Leaks
To check for leaks, remove the preseparator/filter holder assembly and cover the
air inlet at the top of the sam pler body with the palm of the hand while the pump is
running. The ball in the flowm eter should drop immediately to zero and remain
there without movement. If it does not, a leak exists somewhere in the hoses and
fittings between the inlet and the flowmeter. Leaks on the inlet side of the pump
are especially critical, since flow measurement will not accurately reflect the
amount of air passing through the filter. The sampler will be measuring air passing
through the filter, plus whatever air may be entering through the leak.
!Verify that all push-on hose fittings are secure.
!Check the screw fittings attached to the pump. T hese must be screwed in
securely. Unlike p ipe threads these fittings "seat" into their connecting socket.
Do NOT attempt to tighten these fittings with a wrench, since too much
pressure could break them. If any appear loose, tighten by hand to a "finger
snugness."
!Check the push-on hose fitting beneath the 6" white cap just below the quick
connect.
Airmetrics MiniVol Users Guide
12 Airmetrics
This page was intentionally left blank.

Section 3: Controls and Adjustments
Airmetrics 13
3CONTROLS AND ADJUSTMENTS
All Operating Modes
The following controls (see Figure 3.1) are used to set the operation of the
MiniVol in both the particulate matter sampling mode and the gas sampling mode.
ELAPSED TIME TOTALIZER
The Elapsed Time Totalizer displays the total number of hours, with a resolution of
tenths of hours, that the pump has run. The totalizer accum ulates time only while
the pump is running. It cannot be reset to zero. The total hours should be recorded
at the beginning and end of each sampling period.
PROGRAMMABLE TIMER
The Programmable Timer controls the on/auto/off operation of the sampler. The
timer allows up to six sampling times to be preprogrammed over twenty-four hours
or throughout a w eek (see "Prog ramming the Timer").
FLOWMETER
The Flowmeter indicates the flow rate of air through the system in liters/minute.
The flow rate is adjusted using the "Flow Rate Adjustment".
The flowmeter rea dings must be taken from the center of the ball.
FLOW RATE ADJUSTMENT
The Flow Rate Adjustment potentiometer (knob) varies the sampler's flow rate as
indicated by the level of the ball (read from the center of the ball) in the flow meter.
Slowly turn the knob until the air flow reaches the desired level. The sampler's
Flow Control Circuit will attempt to maintain this flow rate by varying the speed of
the pump as particulate matter accumulates on the filter.
Airmetrics MiniVol Users Guide
14 Airmetrics
Figure 3.1. Sampler Controls and Adjustments
12V BATTERY POWER CONNECTOR
The 12V Battery Power Conn ector is a standard ph one plug-in jack which conducts
power from the battery to the sam pler.
LOW FLOW THRESHOLD INDICATOR
The Low Flow Threshold Indicator light is activated when the flow sensor
determines that the air flow rate has dropped som e increment below the flow rate

Section 3: Controls and Adjustments
Airmetrics 15
that was set using the Flow Rate Adjustment and when the Flow Co ntrol Circuit
can no longer maintain the desired flow rate. The size of the increment is adjusted
with the Low Flow Coarse and Fine Adjustments.
NOTE: This light is on whenever the sa mpler is c onnected to a pow er source but is
not operating.
LOW FLOW CUTOFF INDICATOR
If the Low Flow Threshold Indicator is lit for an extended period of time (several
seconds), the flow sensor will shut off the sampler's pump and turn on the Low
Flow Cutoff Indicator light. The red light will remain lit to alert the operator that
the sampling was aborted because air flow could not be maintained at the desired
rate. The pump is turned off because the cut-point of the PM size selectiv e inlet is
determined by the air flow rate through the inlet. For the inlet to have constant
particle size cut-point, it is necessary to maintain a constant flow rate throughout
the sampling period.
When a low flow cutoff condition arises, the sampler can be restarted only by
pressing the "Reset Switch" (see Figure 3.1).
LOW FLOW ZERO &CUTOFF ADJUSTMENTS
The Low Flow Zero and Cutoff Adjustments set the increment below the desired
flow rate at which point the sam pler will shut off. Two potentiometers are used to
set the cutoff point: the Low Flow Zero Adjustment, with a range of adjustment of
approximately 0% to 100% below the desired rate, and the Low Flow Cutoff
Adjustm ent, with an approximate 0% to 20% adjustment range. In particulate
sampling, the desired flow rate is 5 lpm, and the flow rate below which sampling
should be terminated is between 4.5 and 4 lpm, a 10 - 20 percent decrease in flow
rate.
To set a low flow cutoff 10 - 20 percent below the optimal flow rate:
1. Turn the sampler on.
2. Using the Sampling Flow Rate Adjustment, set the desired optimal flow rate as
measured by the Flowmeter.
Airmetrics MiniVol Users Guide
16 Airmetrics
L
3. Set the Low Flow Cutoff Adjustme nt to the zero position (rotated fully
counterclockwise).
4. Adjust the Low Flow Zero Adjustment until the Low Flow Threshold Indicator
lights dimly but the pump continues to run. If the pump shuts off, turn the
Zero Adjustment clockwise and reset with the Lo-Flow/Lo-Battery Reset
Switch. At this point the cutoff flow rate is nearly equal to the optimal flow
rate.
5. Remembering that the L ow Flow Cutoff Adjustment turned fully
counterclockwise is equivalent to a 0 percent less cutoff flow rate and a fully
clockwise setting (.180° rotation) is equivalent to a 20 percent less cutoff flow
rate, turn the Cutoff Adjustment to the position that will yield the desired
cutoff flow rate. For ex ample, if the optimal flow rate w as set at 5
liters/minute and a cutoff flow rate of 4.5 liters/minute is desired, rotate the
Cutoff Adjustment clockwise by 90°.
The absolute low flow cutoff rate can be determined by running the sampler with a
variable restrictor (valve) installed in the inlet tubing. Watch the flow meter w hile
increasing the restriction until the low flow threshold indicator lights. The cutoff
flow rate is the rate indicated by the flowmeter just as the indicator light turns on.
LOW BATTERY INDICATOR
When lit, the Low Battery Indicator means that the battery voltage has dropped to a
limit too low (10.3 volts) to permit continued operation. When the low voltage
limit is reached, the pump shuts off and the low battery indicator turns on and
remains to alert the operator. If the pump was not turned off and the battery
voltage continued to drop, the battery could be perm anently damaged or its life
significantly shortened.
When a low battery condition arises, the sampler can be restarted only by pressing
the "Reset Switch" (see Figure 3.1).
LO-FLOW/LO-BATTERY RESET SWITCH
The Lo-Flow/Lo-Battery Reset Switch restarts the pump when the system has been
shut down due to low flow or low battery voltage conditions (see "Low Flow
Cutoff Indicator" and "Low Battery Indicator" above).

Section 3: Controls and Adjustments
Airmetrics 17
ON/AUTO/OFF BUTTON
The ON/AUTO/OFF Button manually turns the sampler on, off, or places it in the
"Auto" mode. In the "Auto" position, the sampler is controlled by whatever
programmed on/off sequences have been entered. A bar on the lower edge of the
Programmable Timer's LCD display moves from "On" to "Auto" to "Off" as the
button is pressed (see "Programming the Tim er" in Section 2).
Integrated Gas Sampling Option
Integrated bag filling is accomplished with a Valve Driver Circuit board that plugs
into the auxiliary connector on the back of the sampler motherboard. The Valve
Driver Board controls the operation of the two solenoid valves that are mounted on
the board. This arrangement allows for collection of one or two bag samples during
a user selected sampling period. For example, this option allows for collecting two
4- or 8-hour integrated bag samples.
Functionally, sample gas is supplied to the comm on inlet port of each normally
closed solenoid valve by the constant back-pressure of the flow control system. The
sampler pump operates continuously at a pre-set flow rate to purge the system and
supply sample gas to the solenoids under pressure. The output port of each
normally closed solenoid valve is connected to a bag module. Because the pump is
operating continuously during the sampling period, a PM sample may be collected
concurrently with the integrated gas samples.
Electronically, the Valve Driver Board interacts with the Programmable Timer on
the motherboard to perform two functions: 1) control which solenoid valve is
activated, and 2) set the duration and frequency of the "on" time for the active
solenoid valve.
A 4-step circular sequencing circuit advances each time the programmable timer on
the motherboard is switched from the "Auto" to the "Off" mode. There are four
solenoid output connectors with corresponding indicators located in the upper
lefthand corner of the board that the solenoid valves can be plugged onto. The
indicators show the output that is, or will be, active when the sampler is switched
to the "On" mode either m anually or by programmed opera tion. When a solenoid
output is active and the sampler is in the "O n" mode, a solen oid valve plugged onto
the active output pins is opened and closed by a tunable intervalometer circuit.
Both frequency and duration of solenoid valve operation are adjustable to allow the
Airmetrics MiniVol Users Guide
18 Airmetrics
user maximum flexibility in controlling the bag filling rate.
SOLENOID VALVE OUTPUT CONNECTORS
The Solenoid Valve Output Connectors connect the solenoid valves to the
sequencing circuit.
ACTIVE SOLENOID OUTPUT INDICATORS
The Active Solenoid Output Indicator LED above each Solenoid Valve Output
Connector indicates when that set of pins is active. When active the T unable
Intervalometer will open and close the solenoid valve plugged into the
corresponding connector.
MANUAL SEQUENCE ADVANCE BUTTON
The Manual Sequence Advance Button allows the operator to select w hich Solenoid
Valve Output Connector will be active when the pump is turned on. The Manual
Advance only functions when the pum p is off. Each time the pump is turned off,
the channel advances automatically.
PULSE INTERVAL ADJUSTMENT
The Pulse Interval (off time) of the circuit is adjustable over a range of 0-15
seconds by a 16-position rotary switch. This switch is located just to the right of
the solenoid valve output connectors. Switch positions are marked clockwise 0-9,
and continue A-F. The interval between pulses increases in 1-second increments as
the switch is rotated in a clockwise direction. Position "0" enables continuously on.
Position "1" corresponds to a minimum delay time of one pulse per second, and
position "F" indicates the maximum delay of 15 seconds between pulses. The fine
adjustment potentiometer next to this control is for calibrating the one-second
interval (fully counterclockwise - decrease, fully clockwise - increase).
PULSE DURATION ADJUSTMENT
The duration (on time) of each pulse is adjustable over a range of 50-750
milliseconds (ms). This adjustment is made by summing the calibrated interval
values of the dual in-line package (DIP) switches 1-4 on the 5-position DIP switch
located in the upper right corner of the auxiliary board. Each switch has an

Section 3: Controls and Adjustments
Airmetrics 19
assigned "On Time" value, and the on time for each pulse is determined by the
sum of the values of switches in the "off" position. The "On Time" values for each
switch are as follows:
SW-1 = 50 ms
SW-2 = 100 ms
SW-3 = 200 ms
SW-4 = 400 ms
For Example: If SW-1, and SW-4 are in the "off" position, the solenoid on time
for each pulse would be 450 m illiseconds. (50 + 400 ms = 450 ms).
The DOWN position is "on" for these switches. Th e fine adjustment next to this
control adds an extra 50 ms to the total pulse time (fully counterclockwise - adds
50 ms, fully clockwise - adds no time).
POWER ON/OFF
Switch 5 on this DIP switch is the on/off power switch for the auxiliary board, and
must be set to the "on" position for any functions to be active. Th e UP position is
"on" for this switch, the opposite of the other dip switches.
PULSE INDICATOR
The Pulse Indicator flashes when the system is pulsing.
OVERLAP JUMPER
With the Overlap Jumper installed, and solenoid valves plugged into output ports 2
& 4, both valves are energized when the sequencing circuit advances to position #3
(LEDs for positions #2,3,4 are all on at this time). This allows for programming a
sampling period when both bags are filling simultaneously.
Airmetrics MiniVol Users Guide
20 Airmetrics
This page was intentionally left blank.

Section 4: Particulate Matter Sampling
Airmetrics 21
4PARTICULATE MATTER SAMPLING
Sampling procedures for TSP, PM10, and PM2.5 are identical except for the
configuration of the preseparator/filter holder assembly.
Consumables
During particulate matter sampling, the following consumables are needed for
proper operation o f the Min iVol:
!Impactor grease - Glisseal® Ht, Apiezon® M Grease, etc.
!Solvent to mix with grease - hexane, white gas, lantern gas, etc.
!47 mm filters - pure quartz, pure Teflon®, Teflon®-coated glass, etc.
!Petri slides - for storage and transport of the filters.
A microbalance accurate to one microgram is needed to weigh the filters.
Airmetrics offers all of the above consumables (except the solvent), along with
filter weighing services.
Siting Requirements
Siting recommendations in this manual conform to the U. S. Environmental
Protection Agency requirements as stated in the U. S. Code of Federal Regulations
(40 CFR part 58, Appendix E). When operating the sampler in locations under
another jurisdiction, the operator should follow the appropriate guidelines.
The MiniVol should be positioned w ith the intake upward and should be located in
an unobstructed area at least 30 cm from any obstacle to air flow. A ccessibility to
the unit under all weather conditions, along with safety and security of the
monitoring personnel and equipment, should be prime considerations.
Attaching the Mounting Cradle
The MiniVol Mounting Cradle is designed to mount onto a standard 1 1/4 inch
antenna mast or comparable metal tubing (not supplied with the sampler). The mast
Airmetrics MiniVol Users Guide
22 Airmetrics
should be strapped securely to som e other suitable structure)utility pole, parking
meter, fence post, etc. (See Figure 4.1). Available separately from Airmetrics is a
Y-Bracket Assembly which attaches to poles and provides a mast for the mounting
cradle. (Also shown in Figure 4.1).
Preparing the Sampler
If the sampler is equipped with a valve driver board for integrated gas sampling,
make sure to turn off the power (SW-5) on the auxiliary board before sampling
unless integrated gas samples will be collected sim ultaneously with the particulate
matter samples (refer to Section 5, “Integrated Gas Sampling”, for proper sampler
preparation for gas sampling). Be sure that the tubing conforms to the arrangement
shown in Figure 4.2 (if a valve driver board is not attached ) or Figure 5.1 (if a
valve driver board is attached).
TSP - Remove the impactor from the preseparator/filter holder assembly prior
to sampling. Since the impactor will not be used, greasing and cleaning of the
impactor’s target disk need not be done.
PM10 - Use a PM10 impactor in the preseparator/filter holder assembly (see
Figure 4.3). Greasing and cleaning of the impactor’s target disk should be
performed initially and after every seventh sample (or more often if heavy
loading is observed). Refer to Section 7, Maintenance, “Impactor Cleaning.”
PM2.5 - Use a PM2.5 impactor in the preseparator/filter holder assembly and a
PM10 impactor in a multiple impactor adapter mounted on the preseparator
assembly tube but below the rain hat (see Figure 4.4). Greasing and cleaning
of the impactors’ target disks should be performed initially and after every
seventh sample (or more often if heavy loading is observed). Refer to Section
7, Maintenance, “Impactor Cleaning.”
To remove impactors, use your thumb to simply push the impactor out of its tube
from bottom to top. When correctly installed, the impactor’s top is flush with the
surrounding preseparator tube or multiple impactor adapter tube.

Section 4: Particulate Matter Sampling
Airmetrics 23
Figure 4.1. Mounted Sampler
Airmetrics MiniVol Users Guide
24 Airmetrics
Figure 4.2. Tubing Configuration for PM Sampling Mode
Before transporting the MiniVol to the field, perform a laboratory check to
determine if it is operational. Turn the sampler on and observe the motor
performance. Check all tubing for crimps, cracks or breaks. Conduct a flow check
with a "dummy" filter in place to simulate the load against the sampler pump.
Investigate and correct any malfunctions before proceeding. Perform a single-point
flow rate check using a soap-bubble meter or other flow measuring device of
known accuracy and compare to the curve established during calibration. The flow
should be within ± 15% of 5 lpm at current conditions. If the unit fails to operate
in this range, check the sampler for obvious crimps, battery malfunction, etc. The
sampler must be repaired or recalibrated if the flow criteria are not met.
FLOW RATE
The particle size cut point of the preseparator is a function of the velocity w ith
which the air stream passing through the preseparator hits the target. The
preseparator is designed to have the correct cut point at an air flow rate of 5 lpm at

Section 4: Particulate Matter Sampling
Airmetrics 25
ambient conditions. Since the density of air and the behavior of the flowmeter are
functions of the ambient air temperature and atmospheric pressure, a flow rate set
point must be calculated for each different samp ling project.
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 ambient condition. Appendix A co ntains the complete instruction s in
calculating the flow set points.
FLOWMETER CALIBRATION
The sam pler should be recalibrated if the flo wmeter or the pulse dampener is
replaced.
Preseparator/Filter Holder Assembly
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 support screen (see Figure
4.3 for PM10 and Figure 4.4 for PM2.5).
CLEAN AND GREASE IMPACTOR
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. PM10 Preseparator and
Filter Holder Assembly
INSTALLING FILTERS
This procedure should take place in
a laboratory or other clean area.
Contact with and handling of all
filters should be limited to the edges
of the filters. Also, the use of non-
serrated, Teflon®-tipped forceps is
strongly recommended. Filters
should be kept 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
number of the filter mounted 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.

Section 4: Particulate Matter Sampling
Airmetrics 27
Figure 4.4. PM2.5 Preseparator and Filter Holder Assembly
7. Place the entire clean filter assembly into a second plastic bag, or other case,
for transporting to the site. It is best to keep the filter assembly in a vertical
position until installed on the sampler.
Preparing the Battery Pack
BATTERY CHARGING
After each sampling run, the used battery pack should be charged for a minimum
of 18 hours or overnight. The battery need not be completely discharged before
recharging.
Airmetrics MiniVol Users Guide
28 Airmetrics
The rechargeable battery features a green charging light and comes with a
universal transformer that connects to wall sockets by a standard computer-type
power cord. Previous to December, 1997, the batteries featured a red charging
light and were supplied with an 18-VAC Tamura Transformer.
If you own both types of batteries and transformers, please note the following:
!The 18-VAC Tamura Transformer CANNOT charge the new green LED-
equipped batteries. The Tamura Transformer will burn out.
!The new Universal Transformer can charge both types of batteries. The old
batteries, however, will take slightly longer to charge on the Universal
Transformer (18 hours vs. about 14 hours).
DO NO T store the battery while attached to the sam pler as this will cause
irreparable damage to the battery. The indicator lights that remain on when
the battery is con nected to the sa mpler w ill discharge the battery past its 10.3
volt safety cut-off point.
See “Charging Batteries” in the Getting Started section for instructions in the
proper procedure to follow in recharging the batteries.
CHANGING/INSTALLING BATTERY PACK ON SAMPLER
1. Place the charged battery pack beside the sampler.
2. Unclasp the two side latches at the base of the sampler.
3. Lift the sampler off the used battery pack and place the sampler on the charged
battery pack.
Note: The pin on the sampler closest to a side clip inserts into the odd colored
receptacle on the battery pack (see Figure 2.1).
4. Reclamp the two side latches.
OTHER BATTERY CHECKS

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 compartment.
Refer to Section 8, “Troubleshooting” for additional comments 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 sampler 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 ssembly, the sam pler is ready to collect air
samples. Note: For a quick reference to the following steps, see "Particulate
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. Remove the clean Preseparator/F ilter Holder Assem bly from the plastic
transport bag and remove the protective plastic bag under the rain cap. Attach
the assem bly to the sampler top at the quick connect.
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 Manual).
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 beginning flow rate, press the ON /AUTO /OFF button to start
the pump. On the LCD display, the horizontal bar should move to "ON ".
8. If the flowmeter, which should be in the vertical position, indicates zero or a
very low reading, check for restrictions in the tubing, or improperly seated
screw fittings between the pump and the flowmeter.
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
Appendix 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 MUST be in “Auto” mode before the operator leaves.
12. Place the pump and timer assembly back into the sampler body. Replace the
bale assembly bar.
13. Using the hoisting pole, hook the bale assembly bar and raise the sampler, as
vertically as possible, to the m ounting cradle. This 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 of the sampling period, the operator should 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 sampler for extend ed periods. On the Field Data
Sheet record the ambient temperature (Ta), barometric pressure (Pa), and flowmeter

Section 4: Particulate Matter Sampling
Airmetrics 31
reading.
Note: Taand Pareadings may be estimated on site or may be obtained from a
nearby US National Weather Service Forecast Office or airport weather station.
Barometric pressure readings obtained from airports must be at station pressure
(not corrected to sea level), and they may have to be corrected for differences
between the elevation of the monitoring site and that of the airport. If Taand Pa
readings are not available, seasonal av erage tempe rature (Tavg) and barometric
pressure (Pavg) may be substituted. Care must be taken that the actual conditions at
the site can be reasonably represented by such averages. It is therefore
recommended that seasonal values represent actual values within 20 °C and 40
mm Hg.
Note: If a gas sample is also being retrieved, refer to Section 5 “Integrated Gas
Sampling” for proper gas sample retrieval.
1. Remove the sampler from the mounting cradle using the hoisting pole. Position
yourself directly under the sampler, hook the bale assembly bar, and lower the
sampler as vertically as possible. This vertical take-aw ay not only
accommodates the sampler's weight, but prevents the hook from dislodging the
rain cap or damaging the preseparator/filter holder assembly (see Figure 4.1).
2. Place the sampler on a firm level surface.
3. Unscrew either cap of the bale assembly bar and remove the bar. Newer
samplers come with quick-release snap buttons, so the bar need not be
removed.
4. Lift the pump and timer assembly out by the top cap and rest it on the edge of
sampler body using the triangular mount stand. Take care not to pull the
connecting wire loose and hold the top cap.
5. Check the sampler face plate for any error conditions. If an error conditions
exists, refer to the “Error Conditions” section at the end of this chapter.
6. Verify correct time and day of week on time LCD.
7. Record elapsed time as sho wn on the Elapsed Time Totalizer.
8. Obtain ending flow rate:
Airmetrics MiniVol Users Guide
32 Airmetrics
!Press the ON/AUTO/OFF button twice to start the pump.
!With the flowmeter in a vertical position, record flow rate to the nearest
10th of liter/minute (read at center of ball).
Note: If flowmeter indicates zero or very low reading, check the quick-
disconnect to be sure the filter assembly is completely connected.
!Press the ON/AUTO/OFF button twice to stop the pump.
9. Place the pump and timer assembly into the sampler body. Do not replace the
bale assembly bar.
10. Exchange a new preseparator/filter holder assembly for the exposed filter
holder assembly . If possible, perform the exchange inside a building or vehic le
to minimize exposure to the elements. Perform a cross-check of the exposed
filter number with the filter number recorded on the Field Data Sheet for the
run just completed. Also, check the filter number against the site number.
11. Change Battery Pack (see page 28)
12. Obtain beginning flow rate (see "Particulate Matter Sampling Procedure"
above, steps 7 to 12).
13. Make sure the timer is set for the desired period and in the “AUTO” mode.
14. Place the pump and timer assembly back into sampler body . Replace the bale
assembly bar.
15. Using the hoisting pole, hook the bale ba r and raise the sampler, as vertically
as possible, to the mounting cradle.
EXPOSED FILTER
1. In the laboratory, unscrew the filter holder and remove the filter cassette.
2. Locate the petri slide with the filter number which matches the number on the
side of the filter holder assembly. This is the original petri slide in which the

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 number to be sure it matches the number on the petri slide.)
ERROR CONDITIONS
Low Battery Indicator ON
Should the Low Battery Indicator be ON at the end of a sampling period, check the
Elapsed Time Totalizer to determ ine the length of time the sampler ran before
shutting off. 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
performance in the next sam pling period. If the battery fails again, it is most likely
defective and should be replaced.
If a different battery performs in the same manner after shown to be fully charged,
the pump motor is perhaps drawing more current than it should. If possible, install
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 which should be referred to Airmetrics (see Appendix D).
Low Flow Indicator ON
Should the Low Flow Indicator be found ON at the end of sampling 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 power did not fall to the 10.3V lower 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 components (valves, diaphragms). Check 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 maintenance 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 by pressing the Reset Switch. T he system will usually run enough to
perform a brief field inspection and to obtain final flow rates. Pressing and holding
the switch provides continuo us override of the fault circuit.