Performance Standards for Continuous Emission Monitoring Systems-GEHO0403BKAB-E-e

Performance Standards forContinuous Emission Monitoring Systems

Performance standards forgaseous emissions, particulates, temperature,

pressure and flow rate

Environment AgencyVersion 2, Revision 1

April 2003

MCERTS Performance Standards for CEMs, Version 2, Revision 1, April 2003 i

Foreword

The Environment Agency (the Agency) has established its Monitoring Certification Scheme,MCERTS, to deliver quality environmental measurements. The scheme is based oninternational standards and provides for the product certification of instruments, thecompetency certification of personnel and the accreditation of laboratories. MCERTS isprogressively being extended to cover all regulatory monitoring activities.

This document contains the performance standards for continuous emission monitoringsystems (CEMs). CEMs are instruments that are used to make measurements in the hostileenvironments of industrial chimney stacks, flues and ducts, often over widely varying processoperating conditions.

MCERTS for CEMs:

• makes available a certification scheme that is formally recognised within theUK and is acceptable internationally;

• gives confidence to regulatory authorities that instrumentation, once certified,is fit for purpose and capable of producing results of the required quality andreliability;

• gives confidence to users that the instrumentation selected is robust andconforms to performance standards that are accepted by UK regulatoryauthorities;

• supports the supply of accurate and reliable data to the public;

• provides instrument manufacturing companies with an independentauthoritative endorsement of their products, which will facilitate their accessto international markets and increase the take-up of their products in the UK.

The MCERTS performance standards for CEMs described in this document are based onrelevant sections of a number of international ISO or CEN standards, as well as taking intoaccount other relevant national standards.

The determinands covered by the scheme include common pollutants, greenhouse gases andphysical parameters. They are the most important emission and physical parameters whenmonitoring from a wide range of industrial processes. However, as MCERTS develops, theperformance standards will be expanded to cover other determinands and industrialprocesses.

MCERTS provides a formal scheme operating under the requirements of European standardEN 45011 for the product certification of continuous monitoring systems conforming to thesestandards. The Agency has appointed Sira Certification Service (the Certification Body) tooperate MCERTS on its behalf.

MCERTS Performance Standards for CEMs, Version 2, Revision 1, April 2003 ii

The Certification Body has a governing body made up of nominated representatives from thevarious interests served, with no one interest being predominant. The membership includesCEM manufacturers’ trade associations, CEM users and the Agency. The governing body isresponsible for ensuring that the performance of the Certification Body meets therequirements of EN 45011.

Laboratory and field testing under MCERTS must be carried out by laboratories and testorganisations that are accredited to BS EN ISO/IEC 17025. The evaluation of the resultsobtained during the laboratory and field tests will be carried out by the Certification Body,using a group of independent experts known as the Certification Committee.

The Agency has also been working with the German environmental regulator, theUmweltbundesamt (UBA) to align the German and MCERTS performance standards forCEMs. The performance standards in this document reflect this alignment. Furthermore, theAgency has developed and published a procedure for the acceptance of German test reportsfor instruments having approval in Germany. For such instruments, this results in asignificant reduction of testing requirements for certification under MCERTS.

MCERTS certification will also be recognised in Germany, subject to two instruments beingtested, with both instruments meeting all requirements.

If you have any questions regarding the certification process, or would like furtherinformation on how to make an application, please contact:

Sira Certification Service Tel: +44 (0)208 467 2636South Hill Fax: +44 (0)208 295 1990ChislehurstKent BR7 5EH

If you have any general questions about MCERTS, please contact:

Environment Agency Tel: +44 (0)1772 714362Monitoring & Assessment Process Fax: +44 (0)1772 714360Lutra HouseDodd Way, off Seedlee RoadWalton SummitBamber Bridge, Preston, PR5 8BX

or visit the MCERTS website at www.environment-agency.gov.uk/mcerts/

Dr Mick PearsonProcess Manager: Monitoring & Assessment ProcessApril 2003

MCERTS Performance Standards for CEMs, Version 2, Revision 1, April 2003 iii

Contents

1. Introduction ..................................................................................................................... 11.1 Background ............................................................................................................. 11.2 Unique identification of CEMs ............................................................................... 21.3 Modifications to certified CEMs............................................................................. 31.4 Previous performance tests...................................................................................... 31.5 Certificate validity................................................................................................... 4

2. Scope................................................................................................................................. 42.1 Legal drivers............................................................................................................ 42.2 Scope of the MCERTS scheme ............................................................................... 4

3. References ........................................................................................................................ 5

4. Definitions ........................................................................................................................ 6

5. General CEM requirements........................................................................................... 95.1 General requirements for all CEM systems ............................................................ 95.2 Operating conditions ............................................................................................. 105.3 Certification range................................................................................................. 115.4 Zero and span drift ................................................................................................ 12

6. Determinand specific requirements............................................................................. 136.1 Introduction ........................................................................................................... 136.2 Gas monitoring CEMs........................................................................................... 136.3 Total organic compound monitoring CEMs.......................................................... 146.4 Particulate monitoring CEMs................................................................................ 156.5 Flow monitoring CEMs......................................................................................... 156.6 Temperature and pressure monitoring CEMs ....................................................... 16

7. Status of this document ................................................................................................ 16

MCERTS Performance Standards for CEMs, Version 2, Revision 1, April 2003 iv

MCERTS Performance Standards for CEMs, Version 2, Rev1, April 2003 Page 1 of 16

Performance Standards for Continuous Emission Monitoring Systems

1. Introduction

1.1 Background

1.1.1 The Environment Agency established its Monitoring Certification Scheme(MCERTS) to focus initially on the product certification of certain categories ofcontinuous emission monitoring systems (CEMs) used for the measurement ofatmospheric emissions from industrial processes via chimney stacks. The scheme isnow being expanded to cover all areas of regulatory monitoring.

1.1.2 This document specifies the MCERTS performance standards for CEMs. Thedeterminands covered include, but are not restricted to:

• sulphur dioxide (SO2);• oxides of nitrogen (principally NO and NO2, but also N2O);• carbon monoxide (CO) and carbon dioxide (CO2);• hydrogen chloride (HCl);• hydrogen fluoride (HF);• methane (CH4);• sulphur hexafluoride (SF6);• hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs);• mercury (Hg);• formaldehyde;• benzene;• volatile organic compounds, expressed as total organic compounds (TOCs);• oxygen (O2);• water vapour (H2O);• particulate matter;• gas temperature, pressure and flow rate.

1.1.3 The performance standards cover a range of emission levels for large combustionplant, including gas turbines, waste incineration and solvent-using processes.

1.1.4 The general CEM requirements and performance standards to be met by CEMs foreach characteristic are presented in Sections 5 and 6. The requirements forcompliance testing to evaluate the performance of CEMs for conformance to theMCERTS performance standards are given in the document entitled Procedures andGeneral Requirements for the Compliance Testing of Continuous EmissionMonitoring Systems.

1.1.5 The main CEM performance characteristics against which a CEM will be assessedby a combination of laboratory and field testing are:


• linearity;• cross-sensitivity to likely components of the stack gas other than the

determinand;• influence of sample pressure and sample temperature;• response time;• detection limit;• influence of ambient conditions on zero and span readings;• performance and accuracy of the CEM against a standard reference method

(SRM) under field conditions;• reproducibility under field conditions (for particulate monitoring CEMs);• availability and maintenance interval under field conditions;• time-dependent zero and span drift under field conditions;• susceptibility to physical disturbances;• design features.

1.1.6 Product certification comprises three phases. These are:

• Laboratory testing – used to determine performance characteristics, wheresuch testing requires a highly controlled environment.

• Field testing – which is at least three months long. The field test is carried outon processes representative of the intended industrial sectors and applications.

• Product certification – which comprises an audit of the manufacturing processto confirm that the manufacturer has provisions to ensure manufacturingreproducibility and to control any design changes to ensure that they do notdegrade performance below the MCERTS standards.

1.1.7 Test laboratories shall have accredited procedures that comply with the requirementsof EN ISO/IEC 17025 and the requirements of the MCERTS scheme.NOTE: If laboratories carried out performance testing on CEMs before March 2002, then procedures that

comply with the requirements of EN 45001 and the requirements of the MCERTS scheme areacceptable.

1.1.8 Throughout this document, the terms “MCERTS certificate” and “certificate” referto the “MCERTS product conformity certificate”.

1.2 Unique identification of CEMs

1.2.1 All MCERTS certified CEMs shall have a unique designation that unambiguouslyidentifies the equipment as a certified model.

1.2.2 All MCERTS certified CEMs shall have a means of showing the scope ofcertification.NOTE: This could be an identification plate that shows the type of analyser, serial number, certified

determinands and their ranges.

1.2.3 Any changes in the design that have an effect on the performance of the CEM mustbe reflected in the unique designation of the CEM.NOTE: For example, a CEM that has been modified shall be given a new model designation or number to

distinguish it clearly from previous models.


1.3 Modifications to certified CEMs

1.3.1 Modifications to certified measuring systems are allowable so long as manufacturerscan demonstrate that these design changes do not degrade the performance of theCEM below the MCERTS performance standards.

1.3.2 Manufacturers must keep detailed records and drawings of all design changes toCEMs, and have provisions for design verification, inspection and testing to ensurethat the CEMs still meet the required performance standards.

1.3.3 The Certification Body will conduct a regular audit of the design changes to CEMsto meet the requirements of product certification. Manufacturers must notify theCertification Body of any modifications to equipment that may have a significanteffect on CEM performance.NOTE: The audit frequency would typically be annually, but may be every two or three years depending on

circumstances.

1.3.4 Design modifications or extensions to the range of application of a CEM mayrequire renewed conformance testing. The extent of this renewed testing will dependupon the nature of the modifications to the CEM.

1.3.5 If there is evidence that a modification has only limited effects on the performanceof the CEM, then it would not be necessary to retest a CEM completely. In suchcases, only a supplementary test would be required to the applicable MCERTSperformance standards.

1.3.6 In the case of modifications to software – particularly in measuring instruments –detailed documentation (for example, source code) must be presented to theCertification Body indicating the nature of the modification as well as resultanteffects on operation and functionality. The Certification Body will then decide iffurther testing is required.

1.3.7 The certificate will specify a type of sample conditioning system for extractiveCEMs. Sample conditioning systems different from those which were tested duringcertification are allowable so long as the CEM continues to meet the requiredperformance standards and there is independent, verifiable data from a suitablyaccredited laboratory to support this.

1.4 Previous performance tests

1.4.1 MCERTS is developing in line with the evolving requirements of Europeanlegislation and international standards. These developments in turn are influencingthe alignment of national certification and type-approval schemes. This means that,if CEMs have been approved by other schemes, and such schemes are compatiblewith MCERTS, then some or all of the previous test results may be acceptable forMCERTS certification, depending upon the scope of certification required.

1.4.2 The German environmental regulator, the Umweltbundesamt (UBA), operates atype-approval scheme where most of the testing is performed by TÜV testlaboratories.


The Agency and the UBA have formally agreed to align their respective schemes,mutually recognising the testing carried out under both schemes, and to cooperate inthe development of wider international developments, for example, in CEN.

1.4.3 Manufacturers that have test reports to demonstrate conformance with therequirements of the UBA’s type-approval scheme for their CEMs are encouraged tosubmit test reports along with their application for MCERTS certification. TheAgency has a formal procedure, MCERTS - Guidance on the Acceptance of GermanType Approval Test Reports for CEMs, for assessing the test results for compliancewith the MCERTS performance standards.NOTE: Test reports produced to demonstrate conformance with other national schemes may also be

acceptable.

1.5 Certificate validity

1.5.1 MCERTS certificates are valid for five years. After this time, the certification isreviewed and any necessary retesting will be identified to maintain the certification.

2. Scope2.1 Legal drivers

2.1.1 MCERTS for CEMs is designed to meet the requirements of EC Directives and themandatory standards cited within these Directives. The Directives are:

• Directive on the limitation of emissions of certain pollutants into the air fromlarge combustion plants (2001/80/EC).

• Directive on the incineration of waste (2000/76/EC).• Directive on the incineration of hazardous waste (1994/67/EC).

2.1.2 New Directives for incineration and large combustion plants require monitoring andcalibration to be performed according to the requirements of CEN or nationalstandards, while Directives 2000/76/EC and 2001/80/EC require compliance withISO and international standards as well. Therefore, existing or developing CEN orISO standards applicable to CEMs indirectly become legal requirements, and, asMCERTS product certification is based on these mandatory standards, it provides ameans of demonstrating compliance with these legal requirements.

2.1.3 CEN is also developing a new standard for quality assurance of CEMs, which willrequire monitoring equipment to be independently certified or type-approved tointernational and national standards. MCERTS meets this requirement.

2.2 Scope of the MCERTS scheme

2.2.1 The scope of processes within the MCERTS scheme for CEMs is as follows:

• Incineration processes, including those for hazardous waste, co-incineration,municipal waste and clinical waste. In short, those processes covered by theDirective on the incineration of waste (2000/76/EC).

• Combustion processes covered by the Directive on the limitation of emissionsof certain pollutants into the air from large combustion plants (2001/80/EC).


• Solvent-using processes covered by the Solvent emissions Directive(1999/13/EC).

• Gas-fired turbines. While covered by Directive 2001/80/EC, there is evidencethat gas turbines are highly specialised and demanding applications formonitoring, particularly regarding the measurement of low concentrations ofnitrogen dioxide and nitrogen oxide.

2.2.2 CEMs will ordinarily be tested on a highly demanding process, such as a large coal-fired power station, municipal waste incinerator or a gas-fired turbine, depending onthe intended application. The premise is that, if the CEM performs acceptably onthese applications, then experience has shown that CEMs will generally performwell on 95% of other processes. However, there will always be exceptions, and it isthe responsibility of the manufacturer in conjunction with the user to ensure that theCEM will perform adequately on a specific process.

3. References

3.1 Normative references

a) BS EN 45001:1998. General criteria for the operation of testing laboratories.b) BS EN ISO/IEC 17025 (2000). General requirements for the competence of

testing and calibration laboratories.c) Procedures and General Requirements for the Compliance Testing of

Continuous Emission Monitoring Systems – The Environment Agency’sMonitoring Certification Scheme (MCERTS), Version 2, Revision 1, April2003.

3.2 General references

d) BS 6069 Section 4.4 (1993). Stationary source emissions – Determination ofthe mass concentration of sulphur dioxide – Performance characteristics ofautomated measuring methods. Also known as ISO 7935.

e) BS EN 12619 (1999). Determination of the mass concentration of TOC at lowconcentrations in flue gases.

f) BS EN 13526 (2002). Determination of the mass concentration of TOC at highconcentrations in flue gases.

g) BS EN 50081-1 (1992). Electromagnetic compatibility. Generic emissionstandard. Residential, commercial and light industry.

h) BS EN 50081-2 (1994). Electromagnetic compatibility. Generic emissionstandard. Industrial environment.

i) BS ISO 6879 (1995). Air quality – Performance characteristics and relatedconcepts for air quality measurements.

j) BS ISO 10155 (1995). Stationary source emissions – Automated monitoringof mass concentrations of particles – Performance characteristics, test methodsand specifications.

k) BS ISO 14164 (1999). Stationary source emissions – Determination of volumeflow rate of gas streams in duct – automated method.

l) ISO 9169 (1994). Air quality – Determination of performance characteristicsof measurement methods. Also Amendment 1 (CD) (1998).


m) ISO 10396 (1993). Stationary source emissions – Sampling for the automateddetermination of gas concentrations.

n) ISO 10849 (1996). Stationary source emissions – Determination of massconcentration of nitrogen oxides – Performance characteristics of automatedmeasuring systems.

o) ISO 12039 (2001). Stationary source emissions – Determination of thevolumetric concentration of CO, CO2 and oxygen – Performancecharacteristics and calibration of an automated measuring system.

p) BS EN 60359 (2002). Electrical and electronic measurement equipment.Expression of performance

q) MCERTS – Guidance on the Acceptance of German Type Approval TestReports for CEMs, Environment Agency, 2001.

r) VDI 4203, Part 1 (2002). Testing of automated measuring systems. Generalconcepts.

s) VDI 4203, Part 2 (2002). Testing of automated measuring systems. Testprocedures for measuring systems of gaseous and particulate emissions.

4. Definitions

4.1 Accuracy: The closeness of agreement between a single measured value of thedeterminand and the true value (or an accepted reference value).

4.2 Analysis function: Statistical relationship between the starting variable (signalmeasured) of the measuring system and the associated measurement result(measured value) simultaneously determined at the same point of measurementusing a standard method of reference measurement.NOTE 1: The analysis function is normally calculated using linear regression.

NOTE 2: ISO 10155 uses the term “calibration function” instead of “analysis function”. This use of the term“calibration function” conflicts with other ISO standards (for example, ISO 6879) and VDI. WithinMCERTS, the term “analysis function” is used to avoid such inconsistencies.

4.3 Availability: The fraction of the total monitoring time for which data of acceptablequality have been collected.

4.4 Averaging time: The period of time over which an arithmetic or time-weightedaverage of concentrations is calculated. [Ta is the averaging time used by the CEM.Tra is the required data averaging period, e.g. prescribed by legislation.]

4.5 CEM: Acronym for a continuous emission monitoring system. Entirety of allmeasuring instruments and additional devices for obtaining a measurement result.NOTE 1: Apart from the actual measuring device (the analyser), a CEM includes facilities for taking samples

(e.g. probe, sample gas lines, flow meters and regulator, delivery pump), for sample conditioning (e.g.dust filter, pre-separator for disturbing components, cooler, converter) and for recording. Thisdefinition also includes testing and adjusting devices that are required for functional checks and, ifapplicable, for commissioning.

NOTE 2: CEM is an alternative term for “automated measuring system” (AMS), which is the term typicallyused elsewhere in Europe.


4.6 Certification range: The determinand values over which the instrument is to betested, bounded by specified upper and lower limits. Testing takes place within thecertification range.

4.7 Converter efficiency: The efficiency with which the internal converter unit of aNOx analyser reduces NO2 to NO.

4.8 Cross-sensitivity: Response of the CEM to determinands other than those it isdesigned to measure. See Interference.

4.9 Detection limit: This is the concentration value of the determinand below whichthere is at least a 95% level of confidence that the measured value corresponds to asample free of that determinand.

4.10 Delay time, T10: The time taken for the output reading of the CEM to reach 10% ofthe total change in instrument response.

4.11 Expanded uncertainty: Quantity defining a level of confidence about the result ofa measurement that may be expected to encompass a specific fraction of thedistribution of values that could reasonably be attributed to a determinand.NOTE: The level of confidence would typically be 95%.

4.12 Field repeatability: A measure of the 95% level of confidence of the difference ofmeasuring results from two CEMs used under identical conditions.NOTE: The term “reproducibility” is sometimes used instead of “field repeatability”.

4.13 Gas analyser: An analytical instrument that provides an output signal that is afunction of the concentration, partial pressure, flow or temperature of one or morecomponents of a gas mixture.

4.14 Integral performance: The integral performance is defined as a measure of theworking accuracy of the CEM. The integral performance is derived from thedifferences in pairs of measured values of the determinand by the CEM and theSRM. There must be a sufficient number of paired measurements spread over theperiod of unattended operation. It is calculated according to the formula for standarddeviation.

The difference in uncertainties between the measurements from the CEM and thereference methods is defined in equation (1):

2C

2DF SSI −= (1)

where SD is derived from the uncertainty in the differences between the CEM andSRM measurements using equation (2):

−−

= ∑∑==

2

11

2D

11

1 n

ii

n

ii Z

nZ

nS (2)


where

Zi = Xi – Yi;Xi = individual result obtained by the SRM;Yi = mean result obtained by the CEM over the same time period as that taken to

perform SRM measurement;n = number of measurement pairs;SC = known standard deviation in the results obtained by the SRM.

4.15 Interference: A negative or positive effect that a substance has upon the output ofthe instrument when that substance is not the target determinand.

4.16 Interferent: Component of the sample, excluding the measured constituent, thataffects the output signal.

4.17 Limiting conditions: The extreme conditions that an instrument can withstandwithout damage and any decrease in its abilities to perform reliable measurementswhen it is working under its rated operating conditions.

4.18 Linearity: Measure of fit of the instrument’s response to a straight line using anumber of samples of approximately equally distributed concentrations of apollutant and a zero concentration.

4.19 Linearity error: The maximum deviation between the actual analyser readings andthe best-fit line (linear regression line).

4.20 Maintenance interval: Maximum admissible interval of time for which theperformance characteristics will remain within a predefined range without servicing,e.g. refill, calibration or adjustment.

4.21 Output: A reading, or a digital or analogue electrical signal, generated by aninstrument in response to a determinand.

4.22 Performance characteristic: One of the quantities (described by values, tolerances,range) assigned to equipment in order to define its performance.

4.23 Reference conditions: A specified set of values (including tolerances) of influencevariables, delivering representative values of performance characteristics.

4.24 Reference material: A substance or mixture of substances, with a knowncomposition within specified limits. One or more of the properties of the referencematerial are sufficiently well established over a stated period of time to be used forthe calibration of an apparatus, for the assessment of a measuring method, or forassigning values to materials.

4.25 Repeatability: The ability of a CEM to provide closely similar indications forrepeated applications of the same determinand under the same conditions ofmeasurement.


4.26 Response time, T90: The time taken for the output indicator reading of the CEM toreach 90% of the total change in CEM response.

4.27 Span: Difference of the instrument readings between zero and a stated determinandvalue. By convention, this determinand value is chosen to be 70% to 80% of theupper limit of the measurement.

4.28 Span drift: The change in instrument reading in response to a specified value of adeterminand over a stated period of unattended operation.

4.29 Stable test gas mixture: A mixture of gases where the component to be measured isknown and neither reacts with the containment system, nor is adsorbed on to it (e.g.a cylinder).

4.30 Standard uncertainty: Uncertainty of the result of a measurement expressed as astandard deviation.

4.31 Uncertainty: The parameter associated with the result of a measurement thatcharacterises the dispersion of the values that could reasonably be attributed to thedeterminand.

4.32 Zero gas: A gas mixture used to establish the zero point of a calibration curve whenused with a given analytical procedure within a given calibration range.

4.33 Zero drift: The change in instrument reading in response to a zero value of thedeterminand over a stated period of unattended operation.

5. General CEM requirements

5.1 General requirements for all CEM systems

5.1.1 The performance standards within this document apply to complete CEM systems,unless specified otherwise. Where manufacturers do not produce all of thesecomponents themselves, they should supply components from other manufacturersthat they consider suitable for the required purpose(s).

5.1.2 The CEMs shall conform to all applicable EC Directives. These include:

• Electro-Magnetic Compatibility Directive 89/336/EEC and its amendments92/31/EEC and 93/68/EEC.

• Directive 72/23/EEC (known as the Low-Voltage Directive and its amendment93/68/EEC) covering electrical equipment designed for use within certainvoltage limits.

CEM manufacturers or suppliers shall supply independently verifiable and traceableevidence of conformity to all the relevant Directives applicable to the equipment.NOTE: Equipment within the scope of the Hazardous Atmospheres Directive falls outside the scope of this

document.

5.1.3 CEMs shall comply with the requirements of BS EN 60359, Expression of the


performance of electrical and electronic measuring instruments. Manufacturersshall provide evidence of compliance.

5.1.4 All CEMs shall have a means of protection against unauthorised access to analysercontrol functions.

5.1.5 The zero point of a CEM’s display of response shall be located between 10% and20% of the full-scale deflection (FSD). The reference point for span gases shall belocated at approximately 70% of chosen range.

5.1.6 The indicating range of the CEM shall be adjustable to the task in hand.

5.1.7 The CEM shall have a means of connecting an additional indicating and recordingdevice.

5.1.8 The CEM shall have a means of displaying its operating status, for example, normaloperations, stand-by, maintenance mode, malfunctions. The CEM shall also have ameans of communicating the operational status to a remote system.

5.1.9 Particulate CEMs under MCERTS must meet the performance standards for fieldrepeatability.

5.1.10 CEMs that use a cross-stack optical method as the measuring principle shall haveprovisions for either prevention of soiling of the optical system or compensation forits effects.

5.1.11 In the event of an excursion of the measurement beam in cross-stack CEMs, theallowable effect on performance shall be no greater than 2% of the indicating rangefor a maximum allowable deviation angle range of ±0.3°.

5.1.12 Under MCERTS for gas monitoring CEMs, one CEM is required for both laboratoryand field testing, while for particulate monitoring CEMs, two CEMs are required forfield testing. Under the German scheme, two CEMs are required for the laboratoryand field tests for both gas monitoring and particulate monitoring CEMs.The two CEMs must pass all applicable tests. Manufacturers wishing to have theMCERTS certification accepted in Germany will need to meet these requirements.

5.2 Operating conditions

5.2.1 Typical, new emissions limits and associated stack gas parameters for a variety ofprocess, waste incineration and large combustion plant are listed in Table 1. Theseranges are based on legal requirements within recent and developing EC Directives.The MCERTS tests are designed to take these conditions into account. Ranges forcertification should be based on fixed multiples of daily emissions limit values,using the lowest typical limits from EU Directives.


Table 1 Lower emissions limits and combustion parameters, from processes regulatedunder key EU Directives

Determinands Incin-eration

Co-incin-eration

Solidfuels

Liquidfuels

Gaseousfuels

Gasturbines

Solvent-using

processesSulphur dioxide 50 50 200 200 351 – –Oxides of nitrogen 200 200 200 400 200 50 –Carbon monoxide 502 502 502 502 502 – –Hydrogen chloride 10 10 – – – – –Hydrogen fluoride 1 1 – – – – –Total organic carbon 10 10 – – – – 500Particulates 10 30 30 30 5 – –Oxygen (% volume) 11 11 6 3 3 15 21Water vapour 15 15 12 15 20 20 10Flow (m s-1) 20 20 20 20 20 20 15

1 The limit of 35 mgm-3 is for gaseous fuels in general, whereas a 5 mgm-3 limit is set for liquefied gas.2 EU Directives 2001/80/EC and 2000/76/EC allow regulators to set limits. A theoretical limit of 50 mgm-3 is suggested for

setting ranges.

5.2.2 The data in Table 1 give an indication of:

• the conditions with which a CEM might have to contend, and the possibleinterfering components that may coexist with the determinand;

• values for different physical parameters (e.g gas flow velocity) that could beencountered in practice;

• the water-soluble acidic-gases that are generally present in the flue gas, sinceacid condensation could occur if the temperature within the CEM and/or itsassociated sampling line falls below the dew point of these gases.

5.3 Certification range

5.3.1 The CEM manufacturer shall specify and agree with the Certification Body, for eachdeterminand to be measured, the certification range of concentrations over whichthe CEM is to be tested. These ranges shall be chosen subject to the requirements ofparagraphs 5.3.2–5.3.9.

5.3.2 Each certification range will comprise a maximum and minimum value for eachdeterminand. These values must be agreed by the Certification Body as fit for thepurpose of the intended industrial process application and legal requirements.NOTE 1: CEMs may have more than one certified range, although additional ranges will require supplementary

testing to that required for one range alone.NOTE 2: The MCERTS certificate will list all ranges certified and will state explicitly the performance criteria

tested for each range.

5.3.3 Manufacturers wishing to have the MCERTS certification accepted in Germanyshould ensure that the certification range meets the requirements of the relevantGerman legislation governing incineration and combustion processes.NOTE: Here, the maximum in each range is typically 1.5 to 3.0 times the emissions limit for each

determinand. For incineration processes, the range should be 1.5x the daily average limit value.

5.3.4 The minimum value of the certification range will usually be zero, if the CEM isable to measure a zero value. For some determinands (for example, temperature,pressure) and for some CEMs, a zero measurement is not possible, and in this casethe agreed lower limit of the certification range will be non-zero.


5.3.5 The performance standards presented in Section 6 are generally expressed as apercentage of the maximum of the certification range for each determinand. Thus asingle percentage value of the maximum of the certification range, expressed in theappropriate units, is adopted as the largest permitted deviation allowed for each test,regardless of the absolute value of the determinand quantity used in the test.

5.3.6 Optical cross-stack CEMs generally measure in units of determinand concentrationmultiplied by the length of the optical path. In this case the certification range willbe defined in such units, but the path length used for testing will be stated on theMCERTS certificate.

5.3.7 Where the CEM has user-selectable settings (for example, gain and range), thesewill be chosen by the manufacturer, in conjunction with the test-house, to beappropriate to the certification range. It is likely that in practice the CEM rangeselected will be similar to the certification range, although this is not essential.However, the CEM will be tested only over the certification range. The CEMsettings, once chosen, will not be altered during the tests. If certification is granted,the settings used will be stated on the certificate.

5.3.8 If a manufacturer wishes to demonstrate performance over a different range from theagreed certification range, additional testing will be required over each range.

5.3.9 The maximum testable values of the certification ranges, given in Table 2, havebeen set according to peak values that may be experienced within industries. It maybe possible to test higher values, if required, by agreement with the CertificationBody and the chosen test-house(s).

Table 2 Maximum testable values of determinandsDeterminand Maximum determinand valueSulphur dioxide (SO2) 10,000 mg m–3

Nitric oxide (NO) 3,000 mg m–3

Nitrogen dioxide (NO2) 1,000 mg m–3

Carbon monoxide (CO) 1,000 mg m–3

Carbon dioxide (CO2) 30% volHydrogen chloride (HCl) 2,000 mg m–3

Total organic compounds (propane equivalent) 1,000 mg m–3

Oxygen (O2) 30% volWater vapour 50% volParticulate 500 mg m–3

Temperature 600 °CPressure 1,100 mbarFlow velocity 30 m s–1

5.4 Zero and span drift

5.4.1 The CEM shall have a means of calibration and readjustment for zero and span drift.If such adjustments cannot bring the CEM within a normal operational range, thenthe CEM shall have a means of communicating this status to a remote system.


5.4.2 The manufacturer shall provide a description of the technique used by the CEM todetermine zero and span drift. The technique must be sensitive to drift in as many ofthe active components of the CEM as possible. If the CEM cannot measure zerovalues, then the drift shall be measured at the lower limit of the certification range.

6. Determinand specific requirements6.1 Introduction

6.1.1 This section defines the determinand specific requirements for CEMs. The valuesfor individual parameters given in these sections are expressed as a percentage of themaximum of the certification range of the CEM under test, with the exception ofavailability and analysis function.

6.2 Gas monitoring CEMs

6.2.1 Table 3 shows the performance standards for CEMs monitoring gaseousdeterminands.

Table 3 Performance standards for gas monitoring CEMsPerformance characteristic Gases1 other than

HCl, HF and O2

HCl and HF O2

Linearity <±2% <±2% <±0.3% volCross-sensitivity <±4% <±4% <±4%Zero shift due to ambient temperaturechange of 1 °C (∆T = 10 °C)

<0.3% <0.3% <±0.5% vol

Span shift due to ambient temperaturechange of 1 °C (∆T = 10 °C)

<0.3% <0.3% <±0.5% vol

Response time (seconds) <200 <600 <200Detection limit (% of range) <2% <2% <0.2%Detection limit (% of emissions limit)2 <5% <5% –Analysis function/integral performance >95%/<10% >95%/<10% >95%/<5%Availability >95% >95% >95%Zero drift (weekly) <2% <2% <±0.2% volSpan drift (weekly) <4% <4% <±0.2% vol

NOTE 1: The gases will ordinarily include SO2, CO2, NO, NO2, H2O, CO, N2O, SF6, CH4, perfluorocarbons andhydrofluorocarbons. However, other gases or vapours may be included, such as formaldehyde,mercury vapour and benzene.

NOTE 2: This is not applicable to gases where there is not a set emissions limit, for example, greenhouse gasessuch as perfluorocarbons and hydrofluorocarbons.

6.2.2 CEMs that use extractive sampling systems shall have provisions for filtration ofsolids, avoidance of chemical reactions within the sampling system, entrainmenteffects and effective control of water condensate.

6.2.3 When required by the Certification Body, the effect of sample pressure andtemperature shall be tested and the results reported on the certificate. However, thereare no performance standards for these parameters.

6.2.4 NOx ordinarily means nitric oxide (NO) and nitrogen dioxide (NO2). Manufacturersmust specify which of these determinands require certification. CEMs for measuringemissions from gas turbines shall be capable of measuring both NO and NO2.


6.2.5 CEMs that measure total NOx by means of an NO2-to-NO converter shall have aconverter efficiency of at least 95%.

6.2.6 The nominal temperature range is –20 °C to +50 °C, unless assemblies are installedwithin temperature-controlled environments, in which case the required range is+5 °C to +40 °C. The manufacturer submitting a CEM for testing may specify otheroperational ranges, as specified in BS EN 60359.

6.2.7 Manufacturers submitting CEMs for certification for greenhouse gases shall specifywhich perfluorocarbons and hydrofluorocarbons are to be included in the scope ofcertification.

6.3 Total organic compound monitoring CEMs

6.3.1 The performance standards for CEMs monitoring total organic compounds (TOCs)are given in Table 4. There are two different standards – one for CEMs measuringTOCs with concentrations of less than 20 mg C.m–3 of total carbon and another forthose measuring carbon concentrations up to 500 mg C.m–3.NOTE: The standard for the low range of TOC meets the requirements of the Directive on the incineration of

waste, 2000/76/EC and the Directive on the incineration of hazardous waste, 1994/67/EC. Thestandard for the higher ranges of TOC meet the requirements of the Directive on the limitation ofemissions of volatile organic compounds due to the use of organic solvents in certain activities andinstallations, 1999/13/EC.

Table 4 Performance standards for TOC monitoring CEMsPerformance characteristic Low range

0–20 mg C.m–3High range

0–500 mg C.m–3

Detection limit <0.4 mg C.m–3 10% of range1

Linearity1 <±0.4 mg C.m–3 5% of range1

Response time <60 s <60 sEffect of oxygen <±0.8 mg C.m–3 ±5% of range1

Range of response factors: aliphatic hydrocarbons 0.90–1.10 0.90–1.10 aromatic hydrocarbons 0.85–1.1 0.8–1.1 dichloromethane 0.75–1.15 – aliphatic alcohols 0.7–1.0 0.7–1.0 esters and ketones – 0.7–1.0 organic acids – 0.5–1.0Cross-sensitivity <±1.0 mg C.m–3 <±4%Zero drift, period of unattended operation <±2% <±2%Span drift, period of unattended operation <±4% <±4%Temperature-responsive zero drift, per 1 °C (∆T = 10 °C) <±0.3% <±0.3%Temperature-responsive span drift, per 1 °C (∆T = 10 °C) <±0.3% <±0.3%Availability >95% <95%Reproducibility, RD ≥30 ≥30

NOTE 1: Ordinarily based on the emissions limit.



6.4 Particulate monitoring CEMs

6.4.1 The CEM performance standards for particulate monitoring CEMs are given inTable 5. There are separate standards for CEMs used for indicative purposes andthose used for quantitative purposes.


6.4.3 CEMs for quantitative measurements shall have the means of setting at least twoalarm thresholds throughout the entire measuring range.

Table 5: Performance standards for particulate monitoring CEMsPerformance characteristic Quantitative, range

>20mg.m-3Quantitative, range

<20mg.m-3Qualitative

Linearity <±2% <±2% <±2%Zero shift due to ambient temperature change of 1 °C (∆T =10°C)

<0.3% <0.3% <0.3%

Span shift due to ambient temperature change of 1 °C (∆T =10°C)

<0.3% <0.3% <0.3%

Response time (seconds) <200 <200 <200Detection limit - % of range <2% <2% <2%Detection limit - % of emissions limit <5% <5% <5%Analysis function1 >95% >90% >90%Integral performance <10% <20% <20%Availability >95% >95% >95%Voltage effect, at ±15% from the norm <2% <2% <2%Zero drift (weekly) <2% <3% <2%Span drift (weekly) <2% <3% <3%Reproducibility, RD >50 >30 >30

NOTE 1: Compliance with an ISO 10155 level of confidence (95%) of ± 10%.

6.5 Flow monitoring CEMs

6.5.1 Performance standards for gas flow monitoring CEMs are specified in Table 6.


Table 6 Performance standards for flow monitoring CEMsPerformance characteristic RequirementsLinearity <±3%Cross-sensitivity <±4%Detection limit ≤20% of indicating rangeZero shift due to ambient temperature change of 1 °C (∆T = 10 °C) <0.3%Span shift due to ambient temperature change of 1 °C (∆T = 10 °C) <0.3%Response time (seconds) ≤10 sReproducibility, RD ≥30Integral performance <5%Availability ≥95%


6.6 Temperature and pressure monitoring CEMs

6.6.1 The performance standards for temperature and pressure monitoring CEMs arespecified in Table 7.

6.6.2 When required by the Certification Body, the effect of sample pressure shall betested on temperature monitoring CEMs and the effect of sample temperature shallbe tested on pressure monitoring CEMs. There are no performance standards forthese parameters, but the results shall be reported on the certificate.

Table 7 Performance standards for temperature and pressure monitoring CEMsPerformance characteristic Pressure TemperatureLinearity <±2% <±2%Cross-sensitivity <±4% <±4%Zero shift due to ambient temperature change of 1 °C (∆T = 10 °C) <0.3% <0.3%Span shift due to ambient temperature change of 1 °C (∆T = 10 °C) <0.3% <0.3%Response time (seconds) <10 s <10 sDetection limit <2% <2%Integral performance <5%Availability >95%Maintenance interval *Zero drift (per week) <2%Span drift (per week) <4%

7. Status of this document

7.1 These MCERTS performance standards may be subject to review and amendmentfollowing publication of this document. The latest version of the standard, togetherwith guidance on the scheme, is available on the Agency’s website at:

www.environment-agency.gov.uk/mcerts/

7.2 If you have any questions regarding the certification process, including how to makean application, please contact the Certification Body at the address given in theforeword.

Performance Standards for Continuous Emission Monitoring Systems-GEHO0403BKAB-E-e

Documents

Transcript of Performance Standards for Continuous Emission Monitoring Systems-GEHO0403BKAB-E-e