2. • Particulate matter - SPM, Fluoride , Lead, PAH
Temperature , Velocity, Flow
• Gaseous pollutants –
Routine parameters- O2 , CO2 , HC , CO
SO2 , NOx
Acid mist as HCl /H2SO4
Cl2 , NH3 , H2S
2
3. Selection of Sampling location and Minimum
Number of Traverse Points
• Select the sampling location at any cross section of the stack
at least eight stack diameters downstream (8D) and two stack
diameters upstream (2D) from any point of flow disturbance
(bend, expansion, contraction, visible flame, or stack exit)
• Cross section of stack is divided into a number of equal areas
where traverse points are located
• Determine the number of traverse points required.
Inside diameter of stack or duct (m) Number of points
I.D. ≤ 0.3 4
0.3 ≤ I.D. ≤ .6 8
0.6 ≤ I.D. ≤ 1.2 12
1.2 ≤ I.D. ≤ 2.4 20
2.4 ≤ I.D. ≤ 5 32 3
4. Location of traverse points on circular cross section
4
For circular stack divide the cross section into equal parts by two
right-angle diameters, locate half the traverse points symmetrically
along each diameter.
5. Rectangular stacks
• Equivalent diameter shall calculated first,
De = 2 (L) (W) / L + W
• Determine the number of traverse points
• Determine the grid configuration
5
Number of Traverse points Matrix Layout
9 3x3
12 4x3
16 4x4
20 5x4
25 5x5
30 6x5
36 6x6
42 7x6
49 7x7
6. Location of traverse points on rectangular cross section
6
Divide the stack cross-section into as many equal rectangular
elemental areas as traverse points, and then locate a traverse
point at the centroid of each equal area
7. If (8 D – 2 D) criterion cannot be met
• Determine the distances from the measurement site to the
nearest upstream and downstream disturbances
• Divide each distance by the stack diameter or equivalent
diameter, to determine the distance in terms of the number
of duct diameters.
• Determine from Figure the minimum number of traverse
points that corresponds: (1) to the number of duct diameters
upstream; and (2) to the number of diameters downstream.
• Select the higher of the two minimum numbers of traverse
points.
7
10. Example showing circular stack cross section divided
into 12 equal areas, with location of traverse points
10
11. • For stack having dia. > than 0.61 m , no traverse point shall be
located within 2.5 cm of stack wall.
• For stack diameters < than 0.61 m , no traverse point shall be
located within 1.3 cm of stack wall.
• If any traverse points falls within 2.5/1.3 cm of stack wall,
relocate them away from stack wall.
• For elliptical stacks having unequal perpendicular diameter,
separate traverse points shall be calculated along each
diameter.
• Use same traverse points and locations for velocity and
particulate measurements.
11
12. Location of sampling port
• To ensure laminar flow, 8D- 2D
i. Number of sampling port – min. 2 ports are required, so that full
cross- sectional area of stack can be covered for measurements.
ii. Dimensions of sampling port – standard flanged pipe of 0.10 m
inside diameter with 0.15 m bolt circle diameter. Port should
extended outward from the exterior stack wall not less than
40mm, installed at height between 0.90 and 1.2 m above the
floor of working platform.
iii. Platform – If two ports are required at 90o , half of stack
circumference and If four ports are required, entire
circumference ; minimum platform width shall always be 1.2 m
iv. Platform access – caged ladder, stairway, rooftop
v. Platform loading – support load of at least three men and
equipments
vi. Power supply – At platform and stack base 12
14. Iso-kinetic sampling
• Obtaining representative particulate sample
• Kinetic energy of gas stream in stack should be equal to
kinetic energy of gas stream through the sampling nozzle
• If sampling velocity is greater than velocity in duct tube will
suck extra particles, collecting higher percentage of smaller
particles, the sampling will have a lower mass concentration
• If the sampling velocity is less than velocity in duct then tube
will became pressurized and particles will want to be expelled
from the tube. The particles more easily dispelled are small
particles resulted into collection of larger particles ,PM has a
higher mass conc.
14
16. Stack Temperature and Velocity Measurement
• VVM-1
• Temperature- Has a digital pyrometer and thermocouple.
• Velocity- A digital pressure cell (for measurement of pressure
in mm of H2O) along with pitot tube.
16
Thermocouple
Inter-connection
tubings
Carrying
case
Extension for pitot
tube
Pitot tube
Pyrometer
Digital pressure
cell
17. VVM1 - Specifications
i. Temperature range :- Ambient to 600o C
ii. Velocity range :- 0 to 100 m/sec
iii. Thermocouple sensor :- length= 0.6m with 2m long
cable
iv. Manometer :- With 0 – 1300 mm of H2O range
v. Pitot Tube :- S type, 0.6m length with extension of
0.6m.
vi. Inter-Connection tubings :- for inlet and outlet gas
connections
17
18. Stack Temperature and Velocity Measurement
• APM 602
• Temperature- Has a digital pyrometer and thermocouple.
• Velocity- An inclined cum vertical manometer along with pitot
tube.
18
Pitot tube
Thermocouple
sensor
Manometer
Digital
pyrometer
Inter-connection
tubings
Spirit level
19. APM 602 - Specifications
i. Temperature Range : Ambient to 600°C
ii. Velocity Range : 0 to 30 m/sec
iii. Thermocouple sensor : Stainless steel, length of
insertion : 1m with 2m long cable
iv. Manometer : Inclined/vertical Glass Borosilicate
tube with spirit level attached for levelling, max. of
50m/s with red oil & Range increased to 75m/s with
CCl4
v. Pitot tube : Modified S-type ,length- 1m, 1.5m, 2m
and 4m
vi. Interconnection : 3 m long, synthetic rubber tube.
19
20. Temperature Measurement
• Thermocouple is connected with the Pyrometer
• Switch on the pyrometer to measure the Ambient
temperature (Tm)
• Insert the thermocouple sensor into the stack
through sampling port
• Allow the temperature to stabilize for atleast 10
minutes
• Record Stack temperature (Ts) from pyrometer
• Remove the thermocouple
• Hold the sensor by its handle, it is likely to be hot.
20
21. Stack gas velocity determination
• Connect two ends of the manometer marked “pitot” to ends
of Pitot tube (pitot end which has mark is connected to ‘+ve’
end of manometer)
• Manometer sets to zero before hoses are connected
• Insert pitot tube into stack keeping marked end of the tube
facing the air stream
• Plug the clearance between the port hole walls and pitot tube
with asbestos wool to prevent air flow through port hole
• Orient the pitot tube axis and search best alignment (highest
reading )
• Note the manometer reading at various traverse points
• Disconnect the pitot tube when entire cross-section of stack
has been traversed
21
24. i. Stack gas velocity
V = k (2GH Dm/Ds)1/2
here Ds = Da x Ta/Ts
V = 0.2043 x (H x Ts)1/2
where, V = Air velocity (m/sec)
k = Pitot calibration constant (0.890)
G = Acc. Due to gravity, 9.81 m/sec2
H = Manometer reading in mm H2O
Dm= Density of manometer fluid (1000 kg/m3 for H2O)
Ds = Stack gas density ( kg/m3 )
Da = Density of atm. Air (1.25 kg/m3 )
Ta = Ambient air temperature (K)
Ts = Stack gas temperature (K)
24
25. ii. Stack gas volumetric flow Rate
The following equation is used to calculate Qs.
Qs = V x 60 x 1000 x Tm/Ts x A
where,
Qs = Flow rate (lpm)
V = Velocity of stack gases (m/sec)
A = Cross - sectional area of nozzle (m2)
Tm= Absolute ambient gas temperature (K)
Ts = Absolute stack gas temperature (K)
25
26. Nozzles
• Stainless steel (SS 304) with sharp tapered leading edges.
• Minimum recommended internal diameter is 7 mm.
• Select the nozzle size which provides meter sampling rate up
to 30 LPM.
• Nozzle Sizes :-
26
Nozzle
(inches)
Internal diameter
(mm)
Area
(m2)
1/2 12.58 12.4 x 10-5
3/8 8.60 5.8 x 10-5
1/4 6.32 3.1 x 10-5
1/8 3.10 7.5 x 10-6
27. Sampling Period for Particulate matter
• A minimum of 1 m3 of dry gas has been withdrawn
for sampling.
• The mass of particulate matter amounts to atleast 20
percent of the mass of the filtering medium in the
sampler.
• Sampling period should be of lesser duration in
heavy dust concentrations.
• Too short time may give unreliable results and too
long a time may cause resistance of sampling train to
exceeds capabilities of vacuum pump.
27
28. Sampling Period for Gaseous pollutants
Period of sampling Rate of sampling (LPM)
30 minutes 2
1 hour 1
1 to 4 hours 0.5
8 hours 0.2
8 to 24 hours 0.1 to 0.2
28
Based on practical experience over the years of
sampling in India, it is recommended that air
sampling rates which give minimum of evaporation
with reliable efficiency should be :-
29. Handy Stack Sampler APM-620
• The SPM is trapped and collected in a Filter media
• Various gaseous pollutants are absorbed in suitable reagents,
then analysed subsequently by simple wet chemistry methods
to determine the concentrations.
29
Dry gas
meter
Vacuum
pump
Nozzle
Filter
holder
Probe
Sampler
Hose
pipes
Rotameter
30. Handy Stack Sampler APM-620
i. Nozzles : A set of 4 stainless steel nozzles with internal diameter of
12.5mm, 98.6 mm, 6.3 mm & 3.1 mm.
ii. Filter Holder : Stainless steel (SS 304), Suitable to hold (a) cellulose
filtration thimble (size 28mm lD X 100mm long) (b) glass micro fibre
thimble (size 19mm lD X 90mm long)
iii. Sampling Probe : Made from SS 304 , 0.3m and 1 m in length
iv. Impingers : 2 No. (240 ml) and 3 No. (120 ml) borosilicate glass
impingers with Ball socket joints accommodated in ice tray.
v. Rotameter : Used for flow measurement, Plastic body rotameter , 0
– 30 lpm for particulates and 0-3 lpm for gaseous pollutants
monitoring
vi. Dry Gas Meter : Mechanical Type with a range of 40 lpm flow rate.
vii.Vacuum Pump : Monoblock Rotary Vane type, oil lubricated, 0.5 HP
single phase motor (230V) with 50 lpm free flow capacity
30
31. Accessories with Stack Sampler
• Heated Probe - for sampling of flue gases containing high
moisture
• Cyclone - for high dust concentration to avoid choking of
thimbles as in cement plants
• Flourine kit - for monitoring Fluorine / Fluorides
• Carbon monoxide bottle - to collect samples with high CO
levels as in Carbon-black plants and DG sets
• Extension Vacuum Hoses - for sampling ports located at a
distance
• Differential Density Manometer - for monitoring velocities in
low velocity conditions as in natural draft boilers.
31
32. Stack Nozzle
1st impinger set
Silica gel
impinger
Rotameter
Dry Gas
meter
Filter
holder
Probe
Manifold
2nd Impinger set
Stack gases
Stack gases Sampling train for stack gases
Two sets of impingers, one set as gas sampling impingers and
the other set as moisture absorption and estimation impingers,
are used
Rotameter
Vacuum
pump
Mercury
manometer
34. Filter media - Thimbles
• Paper thimbles – used at temp. up to 150o C
• Alundum thimbles – able to withstand high temp. up
to 550o C, high wet strength, chemical resistance
• Glass fibre thimbles – used in heavy dust loading
conditions, able to withstand 550o C of temperature
34
