ISO 9096:1992

IS0
INTERNATIONAL
STANDARD 9096
First edition
1992-06-I 5
Stationary source emissions - Determination of
concentration and mass flow rate of particulate
material in gas-carrying ducts - Manual
gravimetric method
imissions de sources fixes - Mtermination de la concentration et du
debit-masse de matieres particulaires dans des veines gazeuses -
Mthode gravim&ique manuelle
Reference number
IS0 9096: 1992(E)
IS0 9096:1992(E)
Contents
Page
1 Scope .
......................................................................... 2
2 Normative reference
Definitions . 2
Symbols with their corresponding-units, subscripts and index
4.1 Symbols and their corresponding units .
42 . Subscript and index .
Principle .
6 Summary of the method .
............................. 7
7 Review of measurements and calculations
................................................................................... 10
8 Apparatus
8.1 General .
8.2 List of equipment for measurement of particulate
.......................................................................... 10
concentration
............................................................................. 12
8.3 Entry nozzle
...............................................................................
8.4 Probe tube
Particle separators .
8.5
.............................................................. 13
9 Advance preparations
.................................................................................... 13
9.1 General
Selection of a suitable sampling location .
9.2
Minimum number and location of sampling points .
9.3
Size and position of access ports .
94 .
.................................................................... 14
95 I Working platform
Selection of apparatus .
9.6
Check on the suitability of the selected sampling position
9.7
Preparatory work before sampling .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10.1 Preparation of equipment
0 IS0 1992
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permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Genkve 20 l Switzerland
Printed in Switzerland
ii
IS0 9096:1992(E)
............................... 16
10.2 Assembly and mounting of equipment
............................................................... 16
10.3 Area measurement
....................
10.4 Preliminary velocity and temperature survey
................................................................
11 Sampling procedure
.................... 16
11.1 Gas velocity and temperature measurement
........................... 16
-11.2 Number and location of sampling points
............................................................
11.3 Duration of sampling
................................................................................
11.4 Sampling
11.4.1 General .
................................................. 18
11.4.2 Cumulative sampling (3.3)
................................................
11.4.3 Incremental sampling (3.8)
.............. 18
11.4.4 Repeat gas velocity and temperature readings
11.5 Repeat samples .
..................................................................................
12 Weighing
13 Method of calculation .
13.1 General .
13.2 Duct gas flow .
...................................................................
13.3 Sample gas flow
..............................................................
13.4 Sample gas volume
.....................................................
13.5 Particulate concentration
................................................... 21
13.6 Particulate mass flow rate
14 Accuracy .
.
15 Test report . .
Annexes
.......................
A Factors affecting the accuracy of the method
.................................................. 23
A.1 Location of sampling plane
A.2 Number of sampling points. .
. . . . . . . . 23
A.3 Sampling time . . . . . . . . .
A.4 Nozzle design .
...................................................................
A.5 Nozzle alignment
.................................... 23
A.6 Departure from isokinetic sampling
. . .
III
IS0 9096:1992(E)
B Methods and rules for determining the position of sampling points
in circular and rectangular ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
B.l General rule for circular ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
B.2 Tangential rule for circular ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B.3 Rule for rectangular (and square) ducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
C Care and use of Pitot static tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
C.l General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
C.2 Routine examination and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
. . . . . . . . . . . . . . . . . . . . . . . . 26
C.3 Relation of Pitot head to gas flow direction
D Calibration of Pitot tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E Recommendations regarding sampling locations not meeting the
requirement of a straight duct length of seven duct diameters
F Alternative method of determining the particulate mass flow rate in
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
the duct
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
G Bibliography
iv
IS0 9096:1992(E)
-Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
technical committees. Each member body interested in a subject for
which a technical committee has been established has the right to be
represented on that committee. International organizations, govern-
mental and non-governmental, in liaison with ISO, also take part in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Inter-
national Standard requires approval by at least 75 O/o of the member
bodies casting a vote.
International Standard IS0 9096 was prepared by Technical Committee
ISO/TC 146, Air quality, Sub-Committee SC 1, Stationary source emis-
sions.
Annexes A, B, C, D, E and F form an integral part of this International
Standard. Annex G is for information only.

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IS0 9096:1992(E)
INTERNATIONAL STANDARD
Stationary source emissions - Determination of
concentration and mass flow rate of particulate material in
gas-carrying ducts - Manual gravimetric method
WARNING - SAFETY PRECAUTIONS
Sampling operations may involve a variety of hazards depending on the circumstances. All those concerned, e.g. management,
sampling operators and control authorities, shall consider the likely hazards adequately beforehand.
If hazards cannot be eliminated, it will be necessary to make appropriate safety arrangements with regard to any specific local,
national or international regulations before sampling operations commence.
The hazards most likely to be encountered and the means of reducing them include those described below.
On every occasion, plant management and plant operators should be aware that sampling operations are taking place. Management
should consider what appropriate safety procedures, e.g. work permits, should be adopted and ensure that they are understood by all
those likely to be concerned.
HAZARDS TO SAMPLING OPERATORS
a) Working at heights or under conditions of difficult access - Consider a means of escape and the need for guard rails and base
boards (see 9.5), warning systems, etc. Telecommunication will be desirable at remote locations. It is recommended that operators do
not work alone.
b) Exposure to toxic, corrosive or hot gases or dusts thorn the access ports or from elsewhere in the processing plant - Consider
circumstances, monitoring or warning systems, personal protective equipment, etc.
c)
Electrical hazards, from electrical equipment or electrostatic charge - Consider equipment protection, earthing, etc. (see 9.5).
d) Noise and heat from the plant or equipment - Consider protective measures.
e) Handling of heavy or bulky equipment - Consider lifting arrangements and accessibility of sampling location.
HAZARDS TO OTHER PERSONNEL
a) Objects falling from the platform - Consider warning signs, barricading, etc.
b) Presence of temporary equipment, e.g. cables causing trip hazards - Consider warning signs etc.
HAZARDS TO PLANT
a) Ignition of flammable gases - Consider using non-sparking equipment, etc.
b) Equipment dropped into duct system - Take special care that sampling heads etc. cannot become detached.
0,050 g/m3, the inaccuracy of this method will be
1 Scope
greater than + IO % (see clauses 12 and 14).
This International Standard specifies a manual
It is primarily a reference method for the determi-
gravimetric method for the measurement of the
nation of particulate matter emitted from stationary
concentration and mass flow rate of particulate
sources and it can also be used for calibrating
matter in a moving gas stream in confined spaces
automatic continuous particulate monitors. The
such as ducts, chimneys and flues. This method can
method should be applied as much as possible un-
be used to determine concentrations ranging from
der steady state conditions of the gas flow in the
0,005 g/m3 to 10 g/m3.
For concentrations under
IS0 9096:1992(E)
duct. It is not suitable for use on ventilation or air
IS0 3966:1977, Measurement of fluid flow in closed
conditioning systems, indoor atmospheres, or gases conduits - Velocity area method using Pitof static
carrying droplets. tubes.
This International Standard also sets out require-
3 Definitions
ments for the design features of apparatus which
can be used for the determinations if correctly used
For the urposes of this International Standard, the
P
and indicates basic requirements for the positioning
followin definitions
g apply-
of sampling facilities.
3.1 access port: A hole in the duct at the extremity
If any of the requirements of this International Stan-
of a sampling line, through which the sampling
dard are not fulfilled, the method can still be applied
probe is inserted [see figure1 and sampling line
in special cases but the uncertainty on particulate
(3.15)].
concentration or flow rate may be larger (see
clause 14).
3.2 actual conditions: Temperature and pressure
at the sampling points.
3.3 cumulative sampling: The collection of a single
composite sample obtained by sampling for the re-
2 Normative reference
quired period at each sampling point in turn.
The following standard contains provisions which,
3.4 duct; flue; chimney; stack: An enclosed struc-
through reference in this text, constitute provisions
ture through which gases travel.
of this International Standard. At the time of publi-
cation, the edition indicated was valid. All standards
3.5 effective pressure: The difference between the
are subject to revision, and parties to agreements
pressure at the sampling point and the pressure of
based on this International Standard are encour-
the ambient air at equal altitude.
aged to investigate the possibility of applying the
most recent edition of the standard indicated below. 3.6 gas: A mixture of gaseous compounds or el-
Members of IEC and IS0 maintain registers of cur- ements which may carry particulate matter flowing
rently valid International Standards. in a duct.
Area of sampling plane
sltuated wlthln the duct
Sampling llnes 1
Plane of bend
Access port 2
Figure 1 - Illustration of definitions in relation to a circular duct

IS0 9096:1992(E)
3.11 particulate flow rate: Mass of particulate mat-
3.7 hydraulic diameter: The characteristic dimen-
ter contained in a duct gas flow per unit time.
sion of a duct cross-section defined by
4 x Area of sampling plane
3.12 particles; particulate matter: Solid particles, of
Perimeter of sampling plane
any shape, structure or density, dispersed in the
continuous gas phase.
3.8 incremental sampling: The collection and re-
moval of individual samples from each sampling
3.13 representative gas sample: A gas sample
point.
having the same mean particulate concentration as
prevails in the sampling plane during sampling.
3.9 isokinetic sampling: Sampling at a rate such
that the velocity and direction of the gas entering the
The plane normal to the
3.14 sampling plane:
sampling nozzle (v’,) is the same as that of the gas
centreline of the duct at the sampling position (see
in the duct at the sampling point v’, (see figure 2).
figure 1).
3.15 sampling line: The line in the sampling plane
along which the sampling points are located (see
figure I), bounded by the inner duct wall.
3.16 sampling point: Specific location on a sam-
pling line at which a sample is extracted.
. 3.17 sampling location: A suitable position for
carrying out sampling in the duct.
I
,
3.18 site: Works or plant where sampling is to be
I
carried out.
I
I
3.19 standard conditions: Standard temperature
I
and pressure of the gas, i.e. 273 K and 101,3 kPa.
t
4 Symbols with their corresponding units,
V(N
subscripts and index
4.1 Symbols and their corresponding units
lsokinetic sampling
Figure 2 -
See table 1.
4.2 Subscript and index
3.10 particulate concentration: Mass of particulate
matter per unit volume of duct gas at defined gas
temperature and pressure. See table 2.
- IS0 9096:1992(E)
Table 1 - Symbols and their corresponding units
Symbol Meaning Unit
Effective nozzle area
m*
: Sampling plane area
m*
c Particulate concentration *
91m3
6 Thickness of nozzle wall at the tip m
d Duct diameter at sampling plane m
Hydraulic duct diameter at sampling plane m
dH
Inner nozzle diameter
d m
Nl
d Outer nozzle diameter
m
N2
Orifice diameter
Water vapour concentration Tg,rn3
f
-
i Individual position on sampling line (diameter or radius)
-
K Calibration factor
Characteristic length
I m
Greater side length of sampling plane
m
Smaller side length of sampling plane m
m Collected particulate mass
cl
M Molar mass kg/kmol
-
Number of sampling points on sampling diameter
nd
-
Number of sampling diameters (sampling lines)
ndia
-
Number of sampling points on sampling radius (0,&I)
%
-
Number of divisions of 2,
"I
-
Number of divisions of Z2
n2
Absolute pressure Pa
P
Ambient pressure Pa
P am
Effective pressure (p, = p - pam ) Pa
PC8
Differential pressure across flow measuring device Pa
AP
Particulate flow rate in duct
4m g/h
Gas volumetric flow rate m3/h
4v
-
Y Volume fraction of gaseous component
Gas density
kg/m3
P
Sampling time (total) h
t
Sampling time per sampling point h
At
T Temperature (absolute) K
0 Temperature “C
v Gas velocity ms
v Gas volume m
m3/kmol
Molar volume of a gas
vm
Distance from wall to individual sampling point along diameter or radius m
Xi
Table 2 - Subscript and index
Subscript
Meaning
or index
a Actual conditions in sampling plane
Any gas measuring device
g
i Individual value
n Standard conditions
N Nozzle
0 Orifice
Pt Pitot tube
W Water vapour
Moisture included
IS0 9096:1992(E)
- a suction system.
5 Principle
The particle separator and/or the gas metering sys-
A sharp-edged nozzle is positioned in the duct fac-
tem may be either located in the duct, or placed
ing into the moving gas stream and a sample flow
outside the duct.
of the gas is extracted isokinetically for a measured
period of time. To allow for non-uniformity of the
Illustrations of sampling trains are given schematic-
distribution of particulate concentration in the duct,
ally in figures 3 and 4. The numbers in these figures
samples are taken at a preselected number of
correspond to the items listed in table 3 and are dif-
stated positions in the duct cross-section. The
ferent from those used in figures 5 and 6 and in
particulate matter entrained in the gas sample is
clauses 7 and 13.
separated by a filter medium, then dried and
weighed. The particulate concentration is calculated
It is necessary to avoid condensation of vapour
from the weighed particulate mass and the gas
(water, sulphuric acid, etc.) in the sampling train
sample volume. The particulate mass flow rate is
during gas sampling, because it will interfere with
calculated from the particulate concentration and
particle separation, particulate condition and flow
the duct gas volumetric flow rate. The particulate
measurement. To this end, the probe tube, the par-
mass flow rate can also be calculated from the
ticle separator and the gas flow measuring device
weighed particulate mass, the sampling time and
are heated above the relevant dew-point.
the areas of the sampling plane and the nozzle
opening.
The water vapour may intentionally be removed
downstream of the particle separator, to make use
of a dry gasmeter for the measurement of sample
6 Summary of the method
gas volume, if the water vapour content of the duct
gas does not vary appreciably during sampling.
A representative gas sample is withdrawn from the
source. The degree to which this sample represents
For isokinetic sampling, the gas velocity at the
the total gas flow depends on
sampling point in the duct has to be measured, and
the corresponding sample gas flow has to be calcu-
- homogeneity of the gas velocity within the sam-
lated and adjusted.
pling plane;
Normally, a Pitot static tube is used for the meas-
-
a suffi cient number of sampling points in the
urement of duct gas velocity. If the sample gas flow
sampli ng plane;
measuring device is used within the duct, the re-
lation between the measured pressure drop and the
- isokinetic withdrawal of the sample.
Pitot static tube differential pressure is simple, fa-
Normally the gas has to be sampled at more than cilitating the adjustment to isokinetic conditions. If
the gas metering device is located outside the duct,
one sampling point in the sampling plane, depen-
dent on the sampling plane area. This plane is usu- the calculation of the isokinetic sample gas flow rate
ally divided into equal areas, at the centres of which is more complicated. The calculation may also in-
gas is withdrawn (see annex B). To determine the clude the duct gas density under standard con-
particulate concentration in the plane, the nozzle is ditions (which may be derived from the dry gas
moved from one sampling point to the other, ex- composition and the moisture content), the tem-
tracting gas isokinetically at each point. Sampling perature and static pressure of the gas in the duct
and the gas metering device, and the water vapour
periods should be equal for each sampling point,
content of the duct gas, if the sample gas flow is
resulting in a composite sample. If equal sampling
areas cannot be chosen, the sampling period shall measured after water removal.
be proportional to the sampling area.
After sampling, the collected particulate matter is
The sample is extracted through a sampling train,
completely recovered (which can necessitate clean-
which principally consists of
ing of the probe and nozzle), dried and weighed.
-
a sampling probe tube with entry nozzle;
Methods of calculating the particulate concentration
and mass flow in the duct are presented in clauses
- a particle separator, in-stack or external; 7 and 13. An alternative method of calculation of the
particulate mass flow rate in the duct is presented
- a gas metering system, in-stack or external; and in annex F.

- IS0 9096:1992(E)
Velocity measurement
Sample extraction
. .
* 7 --
The numbers correspond to ltems listed in table 1.
Figure 3 - Example of a measuring equipment arrangement (see 8.2), without water removal upstream of the
gas metering device
Velocity measurement
‘I 1
v
i
--
Sample extraction
a
. I
-
: psq ;
-
I
9 7
-
Duct
The numbers correspond to Hems listed In table 1.
Figure 4 - Example of a measuring equipment arrangement (see 8.2), with water removal upstream of the gas
metering device
IS0 9096:1992(E)
particulate matter, including that which was de-
7 Review of measurements and
posited in the sampling train before the filter (19).
calculations
This will give the total mass of collected particulate
matter.
A coherent picture of the necessary measurements
The particulate concentration (22) is calculated as
and calculations for the determination of the
the ratio of the quantity of particulate matter col-
particulate concentration and mass flow is given in
lected (18, 19) to the gas sample volume reduced to
the schematic diagrams of figures 5 and 6. These
standard gas conditions (21).
diagrams are related to the examples of sampling
trains presented -in figures 3 and 4 respectively.
Finally, the particulate mass flow rate (23) can he
Other sampling train arrangements (filtration
obtained by multiplying the particulate concentration
and/or sample flow measurement in-stack) and cal-
(22) by the gas flow rate through the duct (11).
culations (annex F) are possible, provided their
performance is accurate enough to meet the needs
If incremental sampling is used in a given sampling
of this International Standard.
plane, particulate concentrations are averaged, by
giving each particulate concentration a weighting
From figure5 (water removal prior to gas metering)
factor according to the corresponding gas flow rate
it can be seen that, for the calculation of the duct gas
through the duct.
velocity (8) measurement of temperature (3) static
pressure (4) water content (6) and composition (5)
From figure 6 (no water removal prior to gas meter-
of the duct gas will enable calculation of the duct
ing), it can be seen that the calculation of the flow
gas density (7). This is included in the formula for
rate of moist gas through the duct under standard
the velocity calculation together with the measured
conditions (10) follows the same path as in figure 5.
differential pressure (1) if a Pitot tube is used. Using
However, the isokinetic sampling flow rate (12) is
the duct gas velocity (8) and the area of the duct
calculated by relating the differential pressure of the
section (2), the gas flow rate through the duct at dif-
Pitot tube (1) to the pressure drop in the flow rate
ferent gas conditions (9, 10, 11) can be calculated.
measuring device in the sampling equipment (14)
allowing for the different pressures (4, 16) and tem-
For isokinetic sampling, a convenient nozzle diam-
peratures (3, 17) and the suction nozzle diameter
eter is chosen, depending on pump capacity, duct
.
(13)
gas velocity, particulate concentration and sampling
time. The flow rate for isokinetic sampling (12) is
In this example, a conversion to dry gas conditions
determined by the nozzle diameter (13), the duct gas
is not applied. The moist sample gas volume, re-
velocity at the sampling point (8) the gas conditions
duced to standard conditions (20) is derived from
in the duct (3, 4) and the gas meter (16, 17), and the
the moist sample flow rate (14) and the sampling
water content. The sample flow (14) is adjusted ac-
time (24). Knowing the moisture content of the gas,
cordingly.
however, the particulate concentration can also be
calculated on a dry gas basis.
The sample gas volume (15) is measured and the
reading is converted to standard conditions (21) for The particulate concentration based on moist gas,
reduced to standard conditions (22), is calculated
which the static pressure (16) and the temperature
from this sample gas volume (20) and the filter
(17) at the gas meter are used.
weights (18, 19). The particulate flow rate (23) is
The filter material for the collection of particulate found by multiplying this particulate concentration
matter is conditioned and weighed (18) and is then (22) by the moist gas flow rate in the duct at stan-
conditioned and weighed again after collection of dard conditions (10).
-IS0 9096:1992(E)
-----m-- -m----m
-7-n mm-------m
m 4 In \o
cv
. ,
, \ I . w /
.
E
aJ 5
C
d
z
-um
+cn
s
L
da E
5%
aJ
E,,
E
is&
tx
s
l%i
z
3 \
l
I t
Figure 5 - Diagram of measurement and calculation, with water removal before measurement of gas sample
volu~
SAMPLE GAS IN EQUIPMENT
GAS IN FLUE DUCT
Flow rate, moist
-- Temperature m
- I
I
4l
Static
pressure k
I
I )
/
1 Filter weight, 19
4 .
I
loaded
I
I
I
I
I
I
I
I
concentration
I
I
I
Measurements
Calculations
Measurements 1
I
Key
,
Measured value Calculated value - - - - Flow adjustment
Numbers correspond to those in parenthesis in the text of clauses 7 and 13.
S.C. Standard conditions
IS0 9096:1992(E)
should be avoided. The recovery of particles from
8 Apparatus
these surfaces may be difficult. Also, degradation of
the filter by corrosive gases and/or high tempera-
8.1 General
tures may result.
Different types of sampling apparatus may have
8.2 List of equipment for measurement of
particular features that render them suitable only for
particulate concentration
selected applications (e.g. only for the normal range
of boiler flue gas temperatures, or for low concen-
Two gas measuring methods can be distinguished:
trations of particulate matter, or for a certain size of
duct). Use, wherever- possible, the arrangements of
- a gas flow measurement (Method I);
measuring equipment given in figures 3-and 4. The
numbers in these figures correspond to the items
- a gas volume measurement (Method II).
listed in 8.2 and are different from those used in fig-
ures 5 and 6 and in clauses 7 and 13.
If an orifice plate is applied (Method I), the water
vapour content of the sample gas is generally
Sampling and flow measuring apparatus to be used
maintained (see figure 3). This device can also be
in accordance with this International Standard shall,
wherever possible, include facilities for securing the used to adjust and maintain isokinetic sampling. If
apparatus in the access port and for minimizing the an integrating dry gas meter is applied (Method II),
ingress of air or the escape of gases through the the water vapour shall be removed before the gas
access port. The size of the access port shall be enters the meter (figure4). The gas meter will en-
able an accurate measurement of the sample gas
such that the entry nozzle will not be damaged dur-
ing insertion. volume, whereas a separate gas flow measuring
device (e.g. a variable area flowmeter) is essential
Items of apparatus and their requirements comply-
to adjust and maintain isokinetic sampling.
ing with this International Standard are listed in ta-
ble 3. Table3 summarizes the equipment parts necessary
for the measurement of particulate concentration
A general requirement is that the materials used in
and mass flow.
the apparatus shall be resistant to corrosive gases
and prevailing temperatures. Rough internal sur- Part numbers 1 through 17 correspond to the num-
faces, which might cause deposition of particles, bers in figures 3 and 4.
Table 3 - List of equipment parts
Part
Part Specification
Design
number
Entry nozzle See 8.3
2 Probe tube See 8.4
3 Particle separator See 8.5. With an efficiency of
> 98,0 O/o for particles of 0,3 mm
4 Sampling flow rate measuring Orifice plate, flow-meter, equiv- Volumetric flow rate and/or total
device (Method I) alent gas volume, accurate to within
+ 2 %
-
Sampling flow rate control device Two controls advisable (one for
fine adjustment), a stop valve for
blocking the gas flow
Exhauster Pump (Method II), ventilator, fan Capable of extracting gas sample
ejector at required rate against resist-
ance imposed by nozzle, tube,
filter, orifice, etc. When employ-
ing a gas-meter, the pump shall
be gas-tight
Gas volume accurate to within
7 Gas volume meter (Method II) Integrating dry gas meter
+ 2 %
-
When employing a gas-meter,
the pump shall be gas-tight
IS0 9096:1992(E)
Part
Part Specification
Design
number
Sampling flow rate measuring Orifice plate, rotameter, equiv- To control isokinetic sampling,
device (Method II) alent accurate to within + 5 O/o
9 Water removing device (Method Condenser, dryer (e.g. silica gel) To measure water content, accu-
rate to within 1 O/o of gas volume
11)
Thermometer for temperature Accurate to within + 1 % of ab-
10 Thermocouple, temperature
-
solute temperature
measurement in duct probe, equivalent
Instrument for measuring effec- Liquid manometer, equivalent Accurate to within + 0,l O/o of
tive static pressure in duct absolute pressure ii duct
12 Sensitive differential pressure Inclined liquid manometer, Manometer capable
instrument connected to a Pitot equivalent read to within 5 Pa
tube (see part number 13)
Gas velocity measuring device One of the Pitot tubes rec- Calibration against a standard
ommended in IS0 3966; devices Pitot tube to within + 1 % of
not included in IS0 3966 (e.g. velocity (also see annex D)
type S Pitot tube) may also be
considered, if calibrated against
a standard Pitot tube
To measure water content of
14 Instrument for measuring the hu- Condenser, wet and dry bulb,
duct gas to within + 1 % of gas
midity of gases in duct temperature dryer
volume
15 Thermometer for temperature Thermometer, equivalent Accurate to within + 1 % of ab-
-
measurement at gas metering solute temperature
device
Accurate to within + 0,l % of
16 Instrument for measuring effec- Liquid manometer, equivalent
-
absolute pressure in gas meter-
tive static pressure at gas
metering device ing device
17 Sensitive differential pressure Inclined liquid nometer, Manometer capable of being
instrument connected to sam- equivalent read to within + 4 O/o of the
reading
pling flow rate measuring device
(Method I)
Accurate to within + 300 Pa
18 Barometer for measuring local
-
atmospheric pressure
shall not
19 Device for recovering any par- Means should be provided to re- Method employed
ticles which are retained in entry cover all matter deposited in scratch internal su rface
nozzle or probe tube entry nozzle and probe tube
Collected particulate matter
20 Containers for transporting the Containers shall be capable of
particulate matter being sealed; when particulate should not be less than 0,3 O/o of
matter and containers are to be the mass of container to be
weighed together, containers weighed, unless use is made of
should be of lightweight con- a compensating balance capable
struction and capable of with- of weighing to within + 1 O/a of
particulate mass or to the near-
standing drying temperature
est 0,l mg
21 Filter supports and/or Same specification as for part
housi number 20, substituting
nw
“support” or “housing” for con-
tainer
Timing device Timing device shall read to 1 s
22 Timing device shall be fitted with
a start and stop mechanism
23 Accessory particle separators Cyclone, microcyclone, cloth fil-
ter bag, etc.
Provision for heating or cooling
probe tube, particle separator
and sampling flow rate measur-
ing device (Method I)
25 Instrument for gas composition
Gas density accurate to within
Any
analysis + 2 %
-
- IS0 9096:1992(E)
Part
Part Design Specification
number
26 Balance Compensating balances are re- Capable of weighing collected
quired where relatively small particulate matter to within
quantities of particles are to be + 1 % or to the nearest 0,l mg
weighed in containers (see part
number 20)
27 Duct dimension measuring de- Internal dimensions of duct or
Calibrated rod, reliable drawings
vice chimney shall be measured to
for very large ducts
within ,+ 1 O/ of linear dimension
NOTES
8.3 Entry nozzle
1 No reduction should be made in the internal diameter
The entry nozzle is that part of the equipment which
over a distance of one diameter of the entry section.
first admits a sample of the gas to the sampling
train. The nozzle shall be sharp-edged in principle,
2 It is usual for a range of nozzles with different internal
of a simple design, and shall not include
diameters to be supplied with the equipment, so that
encumbrances that might affect the equipment per-
samples can be withdrawn from gas streams flowing at a
formance. An example of a sharp-edged, simple wide range of velocities.
profile is given in figure7. Other mechanically less
vulnerable designs are permissible, provided that
8.4 Probe tube
they comply with the accuracy requirements of this
International Standard.
The probe tube is that part of the equipment which
enables the entry nozzle to be placed within the duct
If 6/dN, is greater than 0,05, the effective diameter
or chimney in order that a sample of gas may be
(C&J shall be calculated using the formula
taken. It usually connects the various items of
VN, + a>* + 42 equipment, such as the entry nozzle, filter, water
d
N=
separator. Any part of the probe tube that is within
J 2
the duct shall be rigid.
The probe tube shall be fitted with a pointer or other
device to indicate the direction in which the entry
nozzle is pointing.
All internal parts of the probe tube up to and in-
cluding the filter shall be smooth and well polished,
and the number of joints shall be kept to a minimum.
I \ I I
Provisions shall be made, in this tube section, for
t
recovering any solids deposited in the probe tube.
Provisions shall be made, if necessary, for heating
/J and 6 may assume any value if d N2 Id N1 s I,1
or cooling of the probe tube without impeding ease
/3 of handling, to prevent any condensation (water va-
pour, sulfuric acid vapour) between nozzle and par-
Figure 7 - Example of shape of the nozzle (1)
ticle separators (or gas metering devices, where
applicable).
The diameter of the nozzle at the entrance shall not
8.5 Particle separators
be less than 4 mm. Any subsequent changes in bore
diameter shall be tapered rather than stepped and
In this International Standard, the particle separator
joints shall be smooth, to prevent deposition. Any
that acts as the final filter in relation to the particles
bends in this section shall have a minimum radius
suspended in the gas sample is referred to as the
of I,5 times the nozzle bore diameter. The internal
main particle separator, even if it is the only sep-
surface shall be smooth and the nozzle made of
arator. The other separators (cloth filter bag,
material which allows smoothness to be maintained.
cyclone etc.) are used to reduce the burden on the
The distance from nozzle tip to nozzle support shall
main filter.
be long enough to avoid flow disturbances which
The main particle separator shall contain a filter
would affect the local gas flow. In normal circum-
medium, suitable for the collection and retention of
stances this would be about three support diam-
the particulate sample with an efficiency of > 98 %
eters.
IS0 9096:1992(E)
for particles of diameter 0,3 pm at 20 “C (e.g. sampling points (see 9.3). This influences the pos-
dioctylphtalate or equivalent test material). Note that itions of the access ports (see 9.4) and the position
the given maximum gas flow through a filter relevant of a working platform (see 9.5).
to the filter efficiency shall not be exceeded (this
From the information gathered, select the test
may dictate filter size).
equipment (see 9.6) and plan the test procedures.
Filters with the most suitable properties for this Discuss with plant management which provisions
purpose are either flat or thimble (fibre) filters. are available or still have to be provided. Any re-
Fibre-packed filters are less well defined in their quirements concerning the avoidance of explosion
particle retention efficiency, depending on the fibre
and fire risks, the availability of suitable connections
diameter and the method of packing. If they are
to the power supply and the compressed air system
used, the fibres shall be sufficiently fine and be
shall be observed. All safety requirements shall be
packed carefully (avoiding channel formation) to a
assessed (see page 1 of this International Standard)
density such that the requirements given in the pre-
and suitable procedures determined and followed.
ceding paragraph are fulfilled. The retention ef-
A check on the suitability of the selected sampling
ficiency of fibre-packed filters shall be checked
position shall precede the proper sampling (see
against a flat (fibre) filter of known efficiency.
. .
9 7)
The filter support shall be designed in such a way
Dates, starting times, duration of survey and sam-
that any deterioration of the filter during its removal
pling periods, as well as plant operating conditions
from the support can be prevented.
during these periods, shall be agreed upon with the
During transportation, the loaded filters should be
plant management.
handled to avoid any loss of material and/or
moisture absorption prior to weighing.
9.2 Selection of a suitable sampling location
Special cases (e.g. soluble or metal-free materials
The sampling location shall be situated in a length
for microscopic or chemical analysis) may require
of straight duct with constant shape and constant
special filter materials. Soda glass fibre or other
cross-sectional area, preferably vertical, and down-
material likely to suffer attack by corrosive gases or
solids shall not be used. Silica, borosilicate or stream as far as practicable from any obstruction
aluminosilicate fibres are generally suitable. which may cause a disturbance and produce a
change in the direction of flow (e.g. a bend, a fan or
The particle separator can be either inserted bodily
a partially closed damper).
into the duct or mounted externally to the duct. In
the latter case, give consideration to heating the To ensure a sufficiently homogeneous gas velocity
separators, to avoid any condensation. In the former distribution in the sampling plane, this section of
case, the dimensions of the separator in relation to straight duct should be at least seven hydraulic di-
the nozzle tip distance shall be selected so that the ameters long. Over the length of the straight section,
gas stream at the nozzle entrance is not affected. locate the sampling plane at a distance of five hy-
draulic diameters from the inlet. If the sampling
The nozzle, probe tube and particle separator are to
plane is to be located in a chimney discharging to
be designed so that the particulate matter that has
the open air, the distance to the chimney top should
deposited upstream of the filter medium can be col-
also be five hydraulic diameters (making a straight
lected easily and quantitatively.
length of ten hydraulic diameters). Choose a section
where the distribution of particles can be expected
to be reasonably uniform. Prior to sampling, ensure
9 Advance preparations
that the gas flow conditions meet the criteria de-
scribed in 10.4.
9.1 General
If sampling in horizontal ducts is unavoidable, there
Before carrying out any measurements, the purpose are practical advantages in having access ports
of the sampling and the sampling procedures shall
situated on top of a duct and due account shall be
be discussed with the plant personnel concerned.
taken of any deposits at the bottom of the duct.
The nature of the plant process, e.g. steady state or
In practice, a straight duct length of seven hydraulic
cyclic, can affect the sampling programme. If the
diameters will often be non-existent where ducts are
process can be performed in a steady state, it is
wide. Selecting sampling planes here would not
important that, during the sampling, the process is
meet the above recommendation of minimum
conducted as nearly as possible under steady oper-
straight duct length. Under adverse gas flow and
ating conditions.
particulate stratification conditions this could lead to
Initially carry out a preliminary survey of the plant
an unacceptable increase of inaccuracy in the re-
to enable the selection of the best sampling location
sults. Under favourable conditions, all other re-
(see 9.2) and the required number and pattern of the
quirements of this International Standard shall be
- IS0 9096:1992(E)
followed to obtain the next best attainable accuracy
See 9.2 for the position of access ports on horizontal
of results. In this case, see annex E for recommen-
ducts.
dations.
A second port may be required downstream of the
sampling plane, if it is necessary to return sampled
gas to the duct because of insufficient fan capacity
9.3 Minimum number and location of
or a toxicity hazard if vented.
sampling points
9.5 Working platform
The minimum number of sampling points is dictated
by the dimensions of the measuring plane. In gen-
SAFETY PRECAUTIONS - The permanent or tem-
eral, this number increases as the dimensions in-
porary platform shall have an adequate working area
crease.
and shall be provided with 0,s m and 1 m high
Tables 4 and 5 give the min
...