1.0 OBJECTIVE:
The provide written procedure for High Volume Air Sample Model – HVS-1,2,3
2.0 SCOPE:
This Standard Operating Procedure covers operation,
Calibration & maintenance of the Instrument.
3.0 RESPONSIBILITY:
Supporting Staff/
Jr. Research Officer/ Research Officer
QA
Officer/ QAM: Governing the Document
4.0 PRE-SAMPLING
TASKS:
4.1 SELECTION OF SAMPLING SITE:
Since sampling is usually
effected at 1.5 meter height, raise the Sampler on the stand or Table.
Ensure that filter is parallel
to the ground.
To obtain a representative
sample, it should not be placed under a tree, near a wall or other obstruction that would prevent free
air flow atmosphe During inclement weather (including
high winds), move the entire sampler to protected location for servicing
when practical. While the sampler is removed from the shelter or before the new filter
is installed, always remove loose particles from the inside surfaces of the shelter
cover and from the surfaces around the filter holder, by wiping them with a clean
cloth. Protect the clean installed filter when returning the sampler to the
sampling site.
4.2 SELECTION OF FILTER MEDIUM
Criteria for filter
selection are good collection
efficiency, high particles & mass loading capacity,
low flow resistance, temperature
stability and non- hygroscopicity.
Glass micro
fiber selection are
particularly suitable for determination of particulates
because of their high retention efficiency combined with low pressur drop, high resistance of blocking
and low alkalinity for moisture. Choice of two types of filter i.e. GF/A, and
EPM-2000 are available for high volume sampling. Whatmann, GF/A, Glass Fiber filter
has been in use for more than 30 years and can be used safely where low trace
element analysis is not required. EPM-200 are spectro quality grade glass
fiber filters and contain very low levels of inorganic and organic contaminants. They are
recommended for use where addition chemical analysis is anticipated. EPM-2000
has been approved by Environmental Protection.Agency of U.S.A. for
National Air Surveillance Network. It does not contain and binding material and maximum purity
is ensured by the use of heat treatment after manufacturing to remove any traces
of organic material. Only the filter having collection efficiency of more than
99 % for particles of 0.3 micron diameters ( as measured by the DOP test
ASTN-D2986-71) are to be used the two types of the glass fiber filters meet
this criteria
Particulate matter that is oily, such as photochemical smog or wood smoke, may block the filter and cause a rapid drop in airflow at a non-uniform rate. Dense fog or high humidity can cause the filter to become too wet and severely reduce the air flow through the filter. Glass-fiber filter filters are comparatively insensitive to changes in relative humidity, but collected particulates can be hygroscopic.
4.3 PREPARATION OF FILTER
Particulate matter that is oily, such as photochemical smog or wood smoke, may block the filter and cause a rapid drop in airflow at a non-uniform rate. Dense fog or high humidity can cause the filter to become too wet and severely reduce the air flow through the filter. Glass-fiber filter filters are comparatively insensitive to changes in relative humidity, but collected particulates can be hygroscopic.
4.3 PREPARATION OF FILTER
Prior to use, each filter
should be visually inspected using a light source. Remove loose fibers with a soft brush.
Discard or return to the supplier the filters with pinholes
and other defects such as tears, creases, or lumps. Always handle the filter papers from its edges and do not
crease or fold the filter prior to use.
5.0 IDENTIFICATION, CONDITIONING & WEIGHING:
Assign
a serial number to each filter. Stamp this number on two diagonally opposite corners, stamp on each side of the
filter. EPM-2000 comes numbered directly from the
manufacturer.
To prevent the filter from getting damaged apply very litter pressure by
pressing
it gently.
Filter
papers, both blank & containing samples should be conditioned containing
active desiccant for 24 hours before
weighing it to minimize errors in the weight; longer periods
Of
equilibration will not affect accuracy. The conditioning environment should
average between 20°C and 25°C and not
very more than ±3°C with relative humidity (RH) less than 50% without varying more than ±5 % RH. A
convenient working RH is 40%.
Weight
the filters to the nearest milligram preferably up to 0.1 mg and record the
weight
and
filters identification number, data in data sheet. Ensure keeping a perforated
plastic
bottle
filled with active silica gel in weighing chamber for minimizing effect of
moisture
during
weighing.
6.0 OPRATION
OF ELECTRONIC CONTROL MODULE:
An
explained earlier, all ECMs i.e. EDM1, ECM2 & ECM3 have minimum common
basic
Function
of Timer/Time Totaliser. This fuction
can be sub-divided into two modes i.e.
DELAY
MODE and SAMPLE MODE.
The
Delay Mode provides an option to the user to start the sampling operation after
a user
Settable
delay time. The sample mode refers to the direct operation of sampling with
immediate running of the blower.
At
power on of the control module, the first message is
During this massge, the micro controller checks the integrity of the
internal non-Volatile
memory. If any error if observed, the same is displayed. For details
see messages of error
conditions.
7.0 DELAY
MODE:
This mode should be used for delayed operation of sampling mode
wherein the first step
is to the delay time.
8.0 Setting
of Delay Mode:
Press DELAY TIME key & the
message on display will be as follows
To set delay time press ENTER Key.
With this selection, a blinking cursor would appear
On the digit of Hours. Use ↑(Increment)
↓(Decrement) to set the desire delay time of Hours.
Every press of ↑ key will increase the hour value by one. Every press of ↓ key
will
Decrement the hour value by one.
ease
note that if either ↑/↓ is kept pressed, then the digits will keep on
incrementing/
Decrementing till the key is
released. Reset key can be used to make the digit value to Zero. Once the desired value for Hours is
set on the display, press Enter Key, the cursor
will
shift to the digit of Mts. Again use ↑/↓ keys to set the Mts. Press of
Enter key will
complete the setting of the Delay
Time.
9.0 ACTIVATION OF DELAY MODE:
The delay mode will
only get activated when of start key is pressed. The display will show
The colon in lower line will be blinking every second. The time left
will be down counted till it becomes zero at which instant, the system will
automatically switch over to Sample
Mode and sampling
will start.
If any power
failure occurs during this mode, then all the time data is stored in the memory
& the system will start automatically, when power is resumed, with
following message for a short time.
After which then earlier message (3) of Time left will be shown. The
operation of Delay mode can be stopped with the press of stop key & the
display will show message no. 3
With no colon
blinking.
If power goes off at this time, then this status is stored &
same message will be shown on resumption of power.
Press of Start key will resume the operation of delay mode.
10.0 MODIFICATION
OF DELAY TIME:
The
modification of set delay time during operation of delay mode is not allowed.
It can
be
done only after stopping of delay mode with stop key. Press ENTER key, the
cursor will appear on Hrs. digits.
Change the values with ↑/↓ keys as explained earlier for Hrs. &
Mts
to the new values. The press of ENTER key will modify and store the new values.
Press of start key will resume the
operation of Delay mode with new delay time values.
11.0 SAMPLE MODE:
During this mode,
the process of sampling of SPM/REPM will proceed with start of blower. At the
end of sampling, the blower will stop. The time of sampling can be set
on the display.
12.0 SETTING OF SAMPLE TIME:
To set Sample Time,
first press the Sample Time Key. With this, following message will
be shown with the
cursor being off.
In
this message, the second line will be blank, at the start of sampling. To set
the Sample
Time, press ENTER
Key. The cursor will appear on the digit of Hrs.
Subsequent to this,
the process of setting of the hours and min. value is similar to Delay
Set Time, as
explained earlier i.e. use ↑ & ↓ key to change the Hrs. digit. Press ENTER
Key to move cursor to Minute digits & so on till cursor disappears.
13.0 OPERATION OF SAMPLE MODE:
At the press of
START Key (in case of Delay time is zero) the blower will get ON immediately.
The second line of the display will start showing the Sample Run Time with
the colon blinking
every second.
The above message
will also appear when the Time Left becomes zero if delay mode has
been used. Thus, at
the start of this phase, the ‘Run Time’ will be zero and every minute, this
Run-Time will be duly incremented by 1 minute. At the end of sampling i.e.,
when the sampling phase equals the Set-Time, then the sampling phase is
terminated and the blower as well as the sampling is stopped. With this
following message is shown.
With this message,
3 long audio beeps are emitted to signify end of sampling.
During the
operation of the sample mode if stop key is pressed any time, the blower power
will be put-off and sampling will stop. The Run-Time on the display message 7
will freeze, colon blinking will stop. If power goes off during this mode, then
on resumption of
power, following
message will appear,
The sampling can be restarted any time with press of start key.
However if power fails during sampling mode, all the relevant time data will be
stored in memory and on power
Resumption, the
sampling will start automatically from the point of interruption. The first
Message for a few
seconds will be message 1 for few seconds the following message will
be shown. This will
be followed by sample mode Run message (7) with
last time values will be on shown in display blinking colon.]
14.0 MODIFICATION OF SAMPLE TIME:
As explained in
delay mode, the sample time can also be modified provided the sampling has been
stopped with press of stop key. With time frozen on display, press ENTER Key.
The cursor will
appear on digits of Hrs. of set time. Modify this value with ↑/↓ keys. Press
ENTER Key & the
cursor will shift to Mts; set the new value of Mts. At press of ENTER
Key, the modified
sample time value be stored in the memory provided that the new sample time
vale is not less than present value of Run-rime as seen on display. However,
if by mistake the
modified sample time value is set less than rum-time, then following message
will be shown for short time.
15.0 DISPLAY OF RUN-TIMER AFTER COMPLETION OF
SAMPLING RUN:
You can view this
value, by pressing the Sample Time key to display the Sample-Set-Time &
Run-Time The message 7 will appear on display with sample time & Run time
being equal. Similarly, to observe Delay Time value, press Delay Time Key. The
set Delay time & Time left will appear on display. This key can also be
used in RUN subsequent to such display values, the above message 8 of run
completion is shown again.
16.0 Start of Fresh Sample Run after Completion
of Previous Run
When the message 8
of sample run completion appears on display, then the values of previous Run
completion, can be reset by pressing RESET Key or Start Key. With this,
Following LCD
message is shown with the cursor on Y (of Yes)
Note that, press
of Enter key with cursor on yes will reset all run time values to zero. This
will also be true for time Left values. However, set value of Delay time &
sample time will remain unchanged.
17.0 ADDITIONAL FEATURES OF ECM 2
As mentioned
earlier, model ECM2 suitable for brush type blower has an extra feature of
varying the sampling flow rate through keys instead of using a potentiometer.
This feather allows precise setting of sampling flow in terms of percentage of
speed control of blower. To activate this mode, press Misc. Key
Press ENTER key and
the cursor will appear on numerical values. Use ↑/↓ keys to increase or decrease the speed. Press ENTER key again
to come out of this mode.
Please note that
there is no one to one relationship between percentage value of speed
control on display &
the flow value as determined by measurement of DP on manometer and
corresponding flow value from the calibration graph.
18.0 ADDITIONAL FEATURES OF ECM 3:
CONSTANT FLOW
CONTROL DURING SAMPLING
In addition to the
timer totalizer functions, the ECM 3 has additional feature of maintaining the
sampling flow constant irrespective of dust load and mains supply voltage
variation. This is
achived by increasing or decreasing the
sampling flow rate through the blower speed control.
*The Sampling flow
is set by moving the sensor block to the required set position on the U-Tube
manometer.
Procedure for Setting the Required Flow:
As explained earlier, the
sampling flow rate should be set at 1.13 M3/Min. for SPM. This is
achieved by first finding the equivalent differential pressure from the
calibration graph & then moving the sensor block to the required position.
The detailed procedure is given bellow:
1. Decide
the Sampling flow
2. Refer to calibration
graph of flow v/s differential pressure in CM WC on U-Tube. Read the DP value
on X-Scale by drawing a horizontal line from the Y-axis for the set flow value
to the curve. Read corresponding value of DP on X-Scale by drawing a vertical
line from the intersection on the curve & horizontal line.
3. Ensure that water
level in manometer is filled upto 0-0 level & there are no bubbles in
water.
4. Divide the value of DP
by 2 and move the pointer sensor block upward from zero level to half of DP
value.
5. Once the blower starts
the water level in manometer right limb will go up while the left limb it will
go down. Once it reaches the sensor block its level will be detected by the
sensor & this information will be sent to the micro-controller. This
position
of water level will
be maintained by the micro-controller. The difference between
the water levels on
the two limbs will be corresponding DP Value of the required set flow.
19.0 USE OF
MISC. KEY:
This
key has two purposes. Before the sampling start, this key can be used to effect
preliminary check for the functioning of the two sensors in the manometer
sensor block. During the Run Mode also, this key can be used to check the flow
status from functioning of these two sources. As can be noted that this flow
status is derived from the water level in
the glass manometer with respect to the Top and Bottom Sensors of the
manometer Sensor Block. Thus when the water level is above or below both the
sensors, then the flow
is
said to be above or below the flow set value. It is only when the water level
is in between the top and bottom sensors, that the flow is declared to be at
set flow:
20.0 USE OF MISC. KEY BEFORE THE
RUN MODE:
Press
of this key before sampling is used to check proper functioning of the sensors.
Following message is shown when this key pressure
During
this test, the blower is started the flow (and hence the water level) is
expected to increase sufficiently high, so that both the top and the bottom
sensor can be tested properly
for
pressure of water.
Press
the ‘START’ key. With this, at first following message is shown and the blower
also
Get
started.
With
blower on, as the flow increases and the resultant ΔP across the
blower ‘Exhaust-Orifice’ causes the water level in the manometer to rise at
first above the bottom sensor. With this, the following single line message is
shown:
When
the flow develops sufficiently high so as to cause the water level rinse above
the top
sensor
as well, then the Top sensor O.K! is displayed on the second line of above
message.
Thus,
when both sensors are declared functionally OK as shown in the above message,
then the blower is put-off. This completes the manometer flow test.
21.0 USE OF
MISC. KEY DURING THE RUN MODE:
During
run mode, when this key is pressed, then one of the following three messages is
shown
appropriately, as per the water level in the glass manometer with respect to
the two
sensors
in the manometer sensor block. These three messages are as follows:
This
will be shown when water level remains in-between the two sensors of the
manometer sensor bock
OR
This
will be shown when water level remains below both the bottom and top sensors of
the manometer sensor block.
OR
This
will be shown when water level remains above both the bottom and top sensor of
the manometer sensor block.
Note
that the Control Module electronics always monitor the water level in the glass
manometer and whenever the level does not remain in between the two sensors,
then the
blower
speed is adjusted in appropriate direction so that the condition corresponding
to
Manometer
at Set-Flow! Is maintained.
22.0 LCD
MESSAGE DURING RUN-SAMPLE-MODE
At the start of this phase, the ‘Control
Module’ starts the blower motor to a predetermined
starting speed. With this, the
blower motor is started and following is shown:
Note
that at the start of this Run-Sample-Time, the second line in this message is
kept black for a while.
Note that the manometer
Sensor Test is effected only at the start of a Fresh Sample-Run
(i.e.
for Run Time beginning from zero). This is to ensure satisfactory operation of
both the sensors of the Manometer Block, right from the start of the Run-Mode,
this Test is not
effected.
After
the blower start, HVS flow increases slowly and the water level in the glass
manometer goes on rising above its initial level. Once, it reaches above bottom
sensor, then following message is inserted in the second line of above message:
After
the above message, the flow increases further and the water level rinses even
above
the
top sensor. With this following message is shown in the second line:
In
this way, the software tests the proper functioning of both the sensors.
23.0 CONSTANT
FLOW CONTROL ACTION DURING SAMPLE-RUN-MODE
After
the above test of Manometer Sensors, the ‘Control Module’ duly adjusts the
blower
speed
in such a way that the water level always remains in between the Top and the
Bottom Sensor of the Manometer Block, i.e. the blower flow is kept constant at
the preset value. In Sample Run Mode, whenever the water level deviates from
this situation, then the blower speed is duly increased / decreased so as to
again restore the water level in between the two sensors.
24.0 ERROR CONDITIONS FOR MANOMETER SENSOR BLCOK
WITH MISC. KEY PRESS :
A. In this ‘Mano. Flow
Test’, at first, the “START” key is expected to be pressed. Thus, at the press
of “START” key (but before the blower start), any of the following Error
situations may be encountered: After pressing the START key, if the water level
in the Manometer is not below both the manometer sensors, then following two
messages are shown one after another:
B. After pressing the START Key, if the water level in the Manometer is
below Top
Sensor
but above the Bot. Sensor, then following two messages are shown one after
another.
C. After pressing the START Key, if the Top Sensor signal is found to
be corresponding to water level above this sensor but Bottom Sensor signal is
not found to be active (i.e.
Bot.
Sensor signal does not correspond to water level above it), then at first
following
Three
messages are shown one after another:
In
this Error situation, check if the Manometer Block position is properly placed
and not over tightened nor kept loose.
D. At the end of Mano.Flow Test, if the water level fails to reach
above the two sensors, then following two messages are shown continuously one
after another
25.0 ERRORS
AT POWER-ON AS
In
case such error has been encountered at power-on, then following two messages
are shown with initialization action of the entire Nonvolatile memory starting
from 00 onwards.
With
the above initialization action, all the data as regards Set and Run time
values of the
Delay-Phase
and Sample-Phase gets initialized to default values.
26.0 METHOD FOR SAMPLING OF
GASEOUS POLLUTANTS:
As
explained earlier, the Sampler has provision to collect four gaseous pollutants
simultaneously while sampling for particulate matter. In case the gaseous
pollutants are to be collected, you may follow the methods that are approved by
the Central Pollution Control Board or Bureau of Indian Standards. These
methods for SO2 & NO2 have been
Described
in detail in Appendix II. For, further information on sampling of other
pollutants i.. H2S, NH2, Cl2 etc., please
check with Central or State Pollution Control Board or BIS .
The
method involves filling each of the impinger tube with a specific adsorbing
solution and then passing known volume of ambient air through the solution at
an appropriate flow rate. The concentration of the pollutants can then be
determined in the lab using specific reagents and spectrophotometer or
colorimeter as per detailed procedure given in each method.
In
Practice, take out an impinger tube and fill it with the adsorbing solution for
SO2 take out 2ng impinger & fill it with specific reagent for
absorption of NO2.
Put
crushed ice or cold water in the impinger box from the opening impinger tube.
This helps in better absorption of pollutants & also reduces vaporation of
reagents when ambient temperature is high. Follow these steps.
i.
At first set a required
Sampling Time at the Control Unit. Also put the filter paper on the filter
holder.
ii.
Now, put-on the HVS equipment.
With the Blower ON, set the desired sampling flow by controlling the respective
needle valve of the manifold after rotameter to the centre tube of the
respective impinger & check the flow rate (Refer the Flow Schematic Diagram
at the end of the Manual) reading.
At
the end of the Sampling, again connect rotameter to the central tube of each
impinger note down this and note down the flow rate. Take the impinger tubes to
the laboratory for analysis. Drain out the water at the Impinger tube Housing
by removing the drain plug. Fix it back after all water is drain out.
Take
average of the initial & final flow, compute the average flow and compute
volume of sampled air by multiplying sampling time in mts to the average flow
i.t.
Initials Flow + Final
Flow
Volume
of sampled gaseous pollutant = -------------------------------- (LPM) X Time
(mts.)
2
Please
note that gaseous pollutants are normally collected for 4 hrs while particulate
sampling will be for 24 hrs. There fore it is important to note down the sample
time & final rate to achieve better accuracy.
DO NOT KEEP THE ROTAMETER
TUBE CONNECTED TO THE CENTER TUBE OF ANY IMPINGER WHILE SAMPLING GASEOUS
POLLUTANTS.
27.0 POST SAMPLING TASKS:
REMOVAL
OF FILTER PAPER
The following procedure should be
used to remove the exposed filter
1. Remove
the pressure plate and lift the exposed filter from the supporting screen by
grasping it gently at
the ends. Under no circumstances one should try to remove filter
paper with blower on.
2. Fold
the filter lengthwise at the middle with the exposed side in, if the collected sample
is not centered on the filter (i.e. the unexposed border is not uniform around the
filter), fold so that only the deposit touches the deposit. An improperly folded filter
where smudge marks from the deposit extend across the borders can reduce the value
of the sample if the analysis for which the sample was collected needs to be divided into equal portions.
3. Check
the filter for signs of air leakage. Leakage may result from a worn pressure plate
gasket or from an improperly installed gasket. If leakage signs are observed,
void the sample, determine
the cause, and take corrective actions.
4. Inspect
visually the gasket face to see if glass fibers from the filter are being left behind
due to over tightening of the face plate wing nuts and to consequent cutting of the filter along the
gasket interface. One can use small amount of talcum powder to provide a thin layer on the
gasket.
5. Check
the exposed filter for physical damage that may have occurred during or after
sampling. Physical damage after sampling would not invalidate the sample if
all pieces of the filter
were put in the folder; however, sample losses due to leakages
during the sampling period or losses of loose particulates after sampling
(e.g. loss when folding
the filter) would invalidate the sample, so mark such samples
void before forwarding them to the laboratory.
6. Check
the appearance of the particulates. Any change from normal colour for example, may indicate new emission sources or
construction activity in the area.
Note any change on the filter folder along with obvious reasons for the change.
28.0 FILTER
LITERATURE AND INSPECTION:
A. Remove the
filter folder from its shipping envelope.
B. Record
the filter number on the hi-vol. field data laboratory date log.
C. Examine
the shipping envelope. If sample material has been dislodged from the filter
with a soft camel’s-hair brush.
D. Examine
the filter. If insects are embedded in the sample deposit, remove them with
Teflon-tipped tweezers, but disturb as little of the sample deposite as
possible If more
than 10 insects are observed, refer the sample to the supervisor for a decision to
accept or reject it.
29.0 FILTER
CINDITUONING:
The exposed filters should be conditioned in a desiccator containing
active desiccant as was done for 24
hours; or move before sampling. One can use an equilibration chamber
with a saturated chemical solution
to get an RH of less than 50% at 20°C. The chamber
is recommended in lieu of a
controlled-temperature/humidity weighing room. And Air
Conditioned room may be used for
equilibration if an RH of less than 50% that is constant
within +/- 5 % and an
air-temperature that is constant within ±3°C are maintained while the filters are equilibrating. A convenient
working RH is 40 % keep hygrometer in the room.
30.0 GRAVIMETRIC
ANALYSIS:
Weight the exposed filter within 30
sec. after removing it from the equilibration chamber to the nearest milligram (mg) preferably up to 0.1 mg on the
analytical balance.
Weigh the filter in the conditioning
environment if possible. If not, be sure that the analytical balance is as close as possible to the
conditioning chamber where it is relatively free
of air currents and where it is at or near the temperature of the chamber.
Record the weight in the laboratory
data log and on the hi-vol. field data form along with
the filter paper before sampling.
31.0 EVALUTING
THE VOLUME OF THE AIR SAMPLED:
For Simple evaluation of volume of
air sampled, follow these steps
a. Note
down the differential pressure DP of the water level at manometer at the start of sampling and find the
corresponding flow from calibration graph. Let it be called Fs.
b. Similarly,
note down the DP of manometer & the corresponding flow at the end of sampling.
Let it be called Fe.
c. Find
the average flow as follow
Fs + Fe
Favg =
------------ Cu.mt/min
2
d. Multiply
the Favg with time of sampling in Minutes to get volume V of sampled air. V =
Favg X Time ( im mt.)
32.0 For
Systematic evaluation of the air volume sampled follows these steps:
1. Note down
the differential pressure with the manometer after every hour and fixed the corresponding dlow in
cubic meter per min. from the calibration graph provided along with the
equipment.
2. At
the end of Sampling, also note down the differential pressure value and the
flow value.
3. For
every hour after the Sampling, start, find out the average flow by adding the flow
values at the start and at the end of the hour and divide the resultant
addition by
two.
4. For
every hour, multiply the average flow for this particular hour by 60 minutes to
find out volume in cubic
meters in this hour.
Evaluate the total volume by adding
all the volume in cubic meters for every hour.
33.0 CALCULATION
OF SPM CONCENTRATION:
The weight of the particulate matter is then divided by the total
volume of the sampled air
to determine the dust concentration
in microgram per cubic meter.
For calculating the SPM
concentration use the following equation
(Wf - Wi)
S.P.M.
Concentration (µg/m3) = ----------------------- X 106
V
Wf =
Final weight of exposed filter in gms.
Wi = Initial
weight of filter in gms.
Record all original
calculations in the data log book.
Of DP on manometer and corresponding
flow value from the calibration graph.
34.0 History
of Revision:
Revision No.
|
Effective
Date
|
Revision
details
|
Reason for
revision
|
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