an introduction to isokinetic source sampling presented by: apex instruments inc. manufacturer of...

An Introduction to An Introduction to

Isokinetic Source Sampling Isokinetic Source Sampling presented by:presented by:

Apex Instruments Inc.Apex Instruments Inc.Manufacturer of Quality Sampling Equipment

“Since 1988”

204 Technology Park Lane

Fuquay Varina, North Carolina 27526tel: 919-557-7300 fax: 919-557-7110

email: [email protected]

web: www.apexinst.com

Apex Instruments Inc.Apex Instruments Inc.

Apex Instruments Inc.

designs, manufactures, and

markets equipment used for

the collection of air samples

from smoke stacks, chimneys,

industrial ducts, and other

process air streams.

Apex Instruments Inc..Apex Instruments Inc..

Emission Data can be used:Emission Data can be used:

GovernmentGovernment

To provide data for determining appropriate

emission limits.

To provide data for determining compliance.

To provide data for health risk assessments.

To provide data for dispersion modeling.

Isokinetic SamplingIsokinetic Sampling

Emission Data can be used:Emission Data can be used:

IndustryIndustry

(continued)

To evaluate air pollution control equipment.

To provide information for design of new

process and control equipment.

To provide information on process operations.


Isokinetic Measurement of Source Emissions:Isokinetic Measurement of Source Emissions:

Particulate emissions from a source are sampled isokinetically using a US EPA Method 5 sampling train. The collected sample is analyzed to determine the pollutant concentrations.


“ISOKINETIC”

ISO = EQUAL + KINETIC = MOTION

Isokinetic Sampling is an equal or uniform sampling of particles and gases in motion within the air stream.


Basic TerminologyBasic Terminology Pmrs = Cs Qs

CONCENTRATION (Cs)

Quantity of pollutant per volume of effluent gas

grams / cubic meter

STACK GAS FLOW RATE (Qs)

Volume of effluent gas per length of time

cubic meters / hour

POLLUTANT MASS RATE EQUATION (Pmrs)

Volume of pollutant gas per length of time

grams / hour


Isokinetic Sampling is the application of five Isokinetic Sampling is the application of five sampling methods developed by the USEPA sampling methods developed by the USEPA plus the applicable method:plus the applicable method:

• Method 1 - Sample and Velocity Traverses from Stationary Sources

• Method 2 - Determination of Stack Gas Velocity and Volumetric Flow Rate

• Method 3 - Gas Analysis for Carbon Dioxide, Oxygen, Excess Air, and Dry Molecular Weight

• Method 4 - Determination of Moisture Content in Stack Gases

• Method 5 - Determination of Particulate Emissions from Stationary Sources


Method 8 Sulfuric Acid Mist & SO2

Method 12 Inorganic Lead

Method 13A Fluorides

Method 17 Particulate Emissions (in stack filter)

Method 23 Dioxin / Furans

Method 26A Hydrogen Chloride

Method 29 Multi Metals

Method 201A Determination of PM10 Particulate

Method 0010 Semi Volatile Compounds

Partial Listing of US EPA Isokinetic Sampling Methods:Partial Listing of US EPA Isokinetic Sampling Methods:


Method 1Method 1 Sample and Velocity Traverses

from Stationary Sources


Method 1 is used to:Method 1 is used to:

1. Select an appropriate sampling location

2. Determine the required number of particulate sampling points

3. Calculate the location of the sampling points within the duct.

B

MEASUREMENTSITE

A

DISTURBANCE

DISTURBANCE

Method 1Method 1

2.0 D e

8.0 D e

Ideal site should be at least 8 duct diameters downstream & 2 duct diameters upstream from any flow disturbance.

Minimum distances are 2 duct diameters downstream and ½ duct diameters upstream from any flow disturbance.

Method 1Method 1

4.0 D e

1.0 D e The number of sample points is dependent on the distance from any flow disturbance (measured in duct diameter).

Method 1Method 1

The following table is used for determining the required number of sampling points.

Method 1Method 1

The cross section is The cross section is divided into the divided into the desired number of desired number of equal areas.equal areas.

Isokinetic sampling is Isokinetic sampling is conducted at discrete conducted at discrete points in the cross-points in the cross-section of the duct .section of the duct .

Method 1Method 1

The following table is used for determining the location of sampling points.

Method 1Method 1

Traverse (Fraction of Stack Dimension from Inside Wall to Traverse Point)

Point Number of Traverse Points Across the StackNumber 2 4 6 8 10 12

1 .146 .067 .044 .032 .026 .0212 .854 .250 .146 .105 .082 .0673 .750 .296 .194 .146 .1184 .933 .704 .323 .226 .1775 .854 .677 .342 .2506 .956 .806 .658 .3567 .895 .774 .6448 .968 .854 .7509 .918 .82310 .974 .88211 .93312 .979

Location of Traverse Points in Circular Stacks

The probe is marked to correspond to the appropriate sampling point using the table from Method 1.

Method 1Method 1

Method 2Method 2Determination

of Stack Gas Velocity and Volumetric Flow Rate


Velocity Velocity Traverses are Traverses are conducted by conducted by measuring the measuring the stack gas stack gas velocity velocity pressure (pressure (p) p) and stack and stack temperature at temperature at each of the each of the sample points sample points determined by determined by the Method 1 the Method 1 calculations.calculations.

Method 2 is used to:Method 2 is used to:

• Conduct a pre-test velocity traverse

• Determine the effluent gas velocity

Method 2Method 2

Pressure Components in Gas StreamsPressure Components in Gas Streams

a) Stagnation Pressure

b) Static Pressure

c) Velocity Pressure, (P)

Method 2Method 2

Type S (Stausscheibe) Pitot TubeType S (Stausscheibe) Pitot Tube

Most commonly used in conjunction with Method 5 because of its:

• Compact size - fits in small ports

• Durability in design

• Plugging resistance in heavy particulate

• Sensitivity at low velocities

Method 2Method 2

Velocity measurements are conducted simultaneously during the sample period for the setting of the isokinetic sampling rate.

Method 2Method 2

Volumetric flows are adjusted for temperature, pressure, and gas molecular weight.

Stack Gas Analysis for Carbon Dioxide, Oxygen, Excess Air,

and Dry Molecular Weight

Method 3Method 3


Method 3Method 3Method 3Method 3

Method 3 is applicable for determining Dry Molecular Weight and excess air correction factors from fossil fuel combustion sources.

Orsat Analyzer

A gas sample is collected in a tedlar bag and analyzed for CO2, O2 and sometimes CO.

Method 3Method 3

Dry molecular weight (Md) is calculated from the gas analysis results

Md = (0.44 % CO2) + 0.32 (% O2) + 0.28 (% CO + % N2)

Method 3Method 3


Determination of Moisture Content in Stack Gases

Method 4Method 4

Method 4Method 4

Moisture Content Procedure

The water vapor is condensed in the impingers. The net gain is measured and the percent moisture is calculated.

* Approximation methods are used to estimate percent moisture for setting isokinetic sampling rates.

Determination of Particulate Emissions from Stationary Sources

Method 5Method 5


Method 5Method 5

Method 5 PrincipleMethod 5 Principle

Particulate matter is withdrawn isokinetically from the source and collected on a glass fiber filter maintained at a temperature in the range of 120 + 14oC.

The particulate mass is determined gravimetrically after removal of uncombined water.

Components:Components: Probe Assembly

Heated Filter Compartment (Hot Box)

Condenser Unit (Cold Box)

Umbilical Cable

Metering Console with Pump

Method 5Method 5

Method 5 SystemMethod 5 System

To obtain a representative sample of particulate matter from an air stream the velocity at the nozzle opening should be equal to the velocity of the approaching gas stream.


100% Isokinetic

100% isokinetic means that the velocity at the tip of the nozzle is equal to stack velocity. The true particulate concentration will therefore be obtained.

Method 5Method 5

Under Isokinetic

When the nozzle velocity is less than the stack velocity the results will be biased high due to the inertia of the large particles.

Method 5Method 5

Over Isokinetic

When the nozzle velocity is greater than the stack velocity the results will biased low since the larger particles break through the air stream and bypass the nozzle.

Method 5Method 5

Tools available for solving isokinetic rate equations include:

Method 5Method 5

Slide RuleSlide Rule

Computer ProgramComputer Program

CalculatorCalculator

PRETEST PREPARATIONSA tared filter is placed in the filter holder

A known amount of water and silica gel is placed in the impingers

A preliminary velocity determination is made to select the proper size nozzle

Sampling train is leak checked

Method 5Method 5

Method 5 ComponentsMethod 5Method 5

Particulate Train Operation

A compliance test will require at least three Method 5 sample runs.

Each run must be for a minimum of 1 hour and 30 scf or other specified minimum time and sample volume.

Sample train placed at first point and sample pump is started

Method 5Method 5

Particulate Train Operation

(cont.)

Sample rate is adjusted to isokinetic after moving to each new sample point and any time the velocity pressure reading changes by more than 20%.

The isokinetic rate setting is determined with a calculator or nomograph and established with a flowrate meter called an orifice meter.

The sampling train is only shut down to move from port to port and at the end of the sample run.

Method 5Method 5

Post Test Operation

Upon completion of testing the sampling train must pass a leak test.

The sample train is removed to a cleanup area that is free of dust and wind.

The filter is removed from the container and placed in a sample container.

Sample is removed from the sample exposed portions of the nozzle, probe liner and filter holder with acetone and placed in a sample container.

Method 5Method 5

AnalysisFilter is desiccated for a minimum of 24 hours and then weighed to a constant weight.

Acetone sample rinse and an acetone blank are evaporated to dryness and weighed to a constant weight. The sample residue is weighed to a constant weight and the residue weight of the acetone is subtracted from the evaporated sample to yield the weight of the sample.

Sum of the weight of the sample on the filter and in the acetone rinse is used to calculate the particulate emissions.

Method 5Method 5

Alternative Sampling Alternative Sampling Trains for ParticulatesTrains for Particulates

Flexible Method 5

Compact Method 5

Method 17

Method 201A


Flexible Method 5Flexible Method 5

Alternative Sampling Trains for ParticulatesAlternative Sampling Trains for Particulates

Uses flexible line between filter unit and condenser

* Heated line may be required for some methods

Compact Method 5Compact Method 5

Includes:

•Heated Stainless Steel Filter Unit

•Stainless Steel Liner

•Flexible Sample Line extension

•Cut-back Umbilical Cable


Method 17Method 17In-stack Filter Applicability


In sources where particulate matter concentration is independent of temperature.

Schematic of the EPA Method 17 Flex Sampling TrainSchematic of the EPA Method 17 Flex Sampling Train

Method 17Method 17

Method 201AMethod 201A


PM10 Sampling Train Constant Sampling Rate

Procedure (CSR)

The PM10 Cyclone is built to EPA specifications for Method 201A testing and is designed for in-stack measurement of particulate matter equal to or less than 10 microns. The cyclone and in-stack filter assembly adapts easily to Method 5 probe assembly.

Method 201AMethod 201A

PM10 Kit

an introduction to isokinetic source sampling presented by: apex instruments inc. manufacturer of...

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