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Response Factor List
In chemistry, a hydrocarbon is a group of chemical compounds consisting only of carbon (C) and hydrogen (H). They all consist of a carbon backbone and atoms of hydrogen attached to that backbone. (Often the term is used as a shortened form of the term aliphatic hydrocarbon.)
For example, methane (swamp gas/marsh gas) is a hydrocarbon with one carbon atom and four hydrogen atoms: CH4. Ethane is a hydrocarbon (more specifically, an alkane) consisting of two carbon atoms held together with a single bond, each with three hydrogen atoms bonded: C2H6. Propane has three C atoms (C3H8) and so on (CnH2·n+2).
There are basically three types of hydrocarbons:
aromatic hydrocarbons, which have at least one aromatic ring in addition to whatever bonds they have saturated hydrocarbons, also known as alkanes, which don't have double, triple or aromatic bonds unsaturated hydrocarbons, which have one or more double or triple bonds between carbon atoms, are divided into:
The number of hydrogen atoms in hydrocarbons can be determined, if the number of carbon atoms is known, by using these following equations:
- Alkanes: CnH2n+2
- Alkenes: CnH2n (assuming only one double bond)
- Alkynes: CnH2n-2 (assuming only one triple bond)
Liquid geologically-extracted hydrocarbons are referred to as petroleum (literally "rock oil") or mineral oil, while gaseous geologic hydrocarbons are referred to as natural gas. All are significant sources of fuel and raw materials as a feedstock for the production of organic chemicals and are commonly found in the subsurface using the tools of petroleum geology.
Hydrocarbons are of prime economic importance because they encompass the constituents of the major fossil fuels (coal,petroleum, natural gas, etc.) and biofuels, as well as plastics, waxes, solvents and oils. In urban pollution, these components--along with NOx and sunlight--all contribute to the formation of tropospheric ozone.
[This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Hydrocarbon"]
Application of FID
The flame ionization measurement is suitable in particular for the direct proof of organically bound carbon. It makes measurements possible within the trace range of some parts by million (ppm) up to process concentrations. in the gas chromatography the flame ionization detector (FID) won therefore a great importance. Increasing interest in measurements in environmental protection and the job monitoring promoted the developments for one application of the FID to the proof of hydrocarbons in the atmosphere. For the air surveillance the immission measurement is interesting in the range under 1ppm, during for the emission measurements, in particular with unburned hydrocarbons in automobile exhaust gases, substantially larger measuring range in question comes. Further areas of application of the FID than total hydrocarbon analyzer are surveillance of plants or areas on toxic concentrations of solvent or the leakage detection and monitoring of fuel camps.
Structure of an FID
The fuel gas H2 or a helium/ hydrogen mixture and the samplegas are given as premixed gas through the burner nozzle into the flame inside the measuring cell. The combustion air flows, usually over an annular gap of the burner nozzle and sweeps past the hydrogen flame from the outside. The ions formed in the flame are collected about two Voltage Electrodes. The DC amplifier converts the resulting ion current (10 -14 ampere) into the measuring signal. The hydrogen and the combustion air are passed through capillaries by means of electric pressure regulators with a constant admission pressure. As a result of constant capillary and gas temperatures in the thermostated analysis chamber of the FID, constant flows occur at the burner block. The sample gas (i.e., either sample gases or calibration gases for zero and test gas) is drawn by a pump and delivered through the sample capillary. To ensure a constant sample flow, the negative pressure of the sample gas at the inlet of the likewise thermostated sample capillary must be kept constant. This is done with an electronic vacuum regulator, which regulates pressure extremely precisely. Older control principles, but according to the current state of the art. The principle of the back pressure regulator that controls the bypass flow or the principle of the back pressure regulator that supplies control air. These two rule principles are listed here for the sake of completeness.
The FID method is based on the ionization of organically bonded carbon atoms in a hydrogen flame and the discharge of the ions produced to a pair of electrodes. The ionic current is measured. The current is proportional, over a wide range, to the number of carbon atoms delivered to the flame per unit time. The molecular structure (e.g. single or double bond, number and nature of hetero-atoms, chain length and ring- structure) has a considerable influcnce on the oxidation properties of the carbon and thereby on the height of the detector signal. Consequently, organic compounds with oxygen as hetero-atom are generally indicated with far less sensitivity than pure hydrocarbons with the same number of hydrogen atoms per molecule. The different sensitivities to different organic compounds are expressed as response factors. These are specific to substance and apparatus (dependence on nozzle shape, electrode, combustion chamber, and combustion air admixture) and cannot be transferred to other FIDs.
Measuring principle FID
The flame ionization detector measures the sum of organically bound constituents in the hydrocarbon compounds.
The application of an electric field produces an ion current of the order of 10-14 amps. When a hydrocarbon-containing sample gas is supplied to this flame, the ion current increases in proportion to the carbon content of the HC compound. As fuel gas wants to use pure hydrogen H2 or a H2/He-mixture in ratio 40:60. Calibration of the FID is normally made in ppm C3H8 (propane) or ppm CH4 (methane). Practitioners speak of a calibration on C3 or C1 and modern measuring devices and show this directly. In addition, a calibration in mgC / m3 is common practice - especially with officially arranged emission monitoring systems, whose limit values are usually given in mgC / m3.
Reactions in the FID measuring cell
Das Meßprinzip des Flammenionisationsdetektors (FID) beruht auf der Ionisation von Kohlenwasserstoffmolekülen in einer Wasserstoff- Diffusionsflamme und der anschließenden Absaugung der freien Ladungsträger durch eine Elektrode im elektrischen Feld. Die Ionisierung erfolgt durch Chemoionisation. Der Bereich der Diffusionsflamme ist folgendermaßen aufgebaut(A) Burner nozzle
A mixture of ultrapure hydrogen and sample gas containing the hydrocarbons to be measured flows through the microfine nozzle bore. On the outside of the burner nozzle you can see the combustion air flow for the flame.(B) Inner flame zone (= pyrolysis zone, directly at the outlet of the nozzle bore)
The mixed gas is used to the outlet from the burner nozzle.
In the further course, pyrolytic cleavage processes take place,
C2H6 + H * ---> C2H5 * + H2
C2H5 + H * ---> 2CH3 *
This gives rise to radicals such as CH 2 *, CH *, C *(C) Outer flame zone (= oxidation zone, envelops the pyrolysis zone)
This is only a few 1/100 mm thick. In her the main reactions to the ion formation take place. Diffused by the outside passing combustion air (therefore "diffusion flame"!) The oxygen content to the pyrolysis zone and from the inside of the nozzle bore escapes the hydrogen and the hydrocarbon radicals from the pyrolysis zone. The most important reaction occurring is:
CH * + O * ---> CHO (excited state) ---> CHO + + e-
This process is called chemoionization. The CHO + ion is the primary charge carrier responsible for the detector signal. The ion yield of this reaction is relatively low. Only about one out of 500,000 hydrocarbon atoms forms an ion pair. However, since the basic ionization of the pure hydrogen flame is reduced by several orders of magnitude, the FID nevertheless has a relatively low detection limit (detection limits below 50ppb methane are possible.). Inorganic compounds such as CCl4, CS2, HC1, etc., which can not form CH * radicals, are not detected by the FID or by several orders of magnitude of different sensitivity. (D) Ambient oxidizing atmosphere
The products of combustion from zone (C) are released to the outside atmosphere. The resulting ions also pass through this area. On the way to the suction electrodes recombination processes can occur which reduce detector sensitivity, which
CHO + + 0H -> CHO + OH
H30 + + e-> H20 + H
Sampling during the FID measurement
- Depending on the application, requirements are placed on the FID and on the prescribed sample preparation. Thus, a heated pre-filter, heated sample switch or heated sample line should meet the following requirements. Absolutely essential is the seamless heating of the samplepath to prevent any condensation. But even the removal of the solid particles from the sample gas through the heated pre-filter is particularly important for the life of the unit. Special attention should also be given to the appropriate choice of materials for aggressive and acid sample gases.
- When selecting the material of the sample carrying components, be careful and ensure that there is no influence on the measuring gas (katalytic preoxidation because of specific metals) and that material is resistant to the sample gas and the temperature. For hydrocarbons, the catalytic effect of nickel is mostly important.
- The test gas is applied either directly in the FID or given up on the heated pre-filter, whereby the entire measuring system is calibrated.An analyzer temperature suitable for the measurement task must be determined, based on the boiling point calculation. For this purpose, the boiling points of the hydrocarbons you want to measure should be determined and the analyzer temperature should be at least 10 °C higher. Also the pre-filter and the heated pipe should be set to this temperature.For exhaust gas measurement with FID and engine test benches, the temperature has to be set at 191°C according to US-EPA specifications. This is also referred as 191° EPA.
- It is also important that no "cold spots" are found in the sample gas flow when measuring hydrocarbons; these are typically unheated solenoid valves or fittings (tees) and unheated short conduits made of stainless steel or PVDF.
- For very large soiling caused by solid particles, a pre-filter is indispensable. For this purpose, the use of a backflush filter (automatically after time interval) or also prefilter with exchangeable filter elements is recommended. It should be noted that due to their good thermal conductivity, titanium filters or stainless steel filters are better than ceramic filters, to which hydrocarbons can usually adhere well.
- Whether the sampling probe is to be heated must be clarified depending on the measuring task. With ambient air measurements (workplace measurements), an unheated PVDF or stainless steel hose is neccessary, whereas in combustion processes the use of heated analysis lines is always recommended.
Measure hydrocarbons correctly with the FID
For a broad range of tasks in the chemical industry, the overall hydrocarbon technology must be able to demonstrate optimal metrological problem solutions. Due to the high relevance of the measurement results obtained for compliance with the legal requirements in environmental, explosion and occupational safety, the problem analysis, the system selection and later the interpretation of the measured values are asked for expert knowledge.Response factors
The FID measurement signal corresponds directly to the number of C-atoms in the sample gas flow. However, depending on the molecular structure of the measured species, the FID shows a different response. This substance-specific response is described by response factors.
Important: When comparing measurement results, the differing response factor at the result interpretation must be integrated into calculation.
Thus, different levels of benzene concentration can be measured even though each unit was calibrated with the same propane calibration gas. Each of these measured values is equal to "correct". The value for the benzene response of the device must be the same concentration value supply.
With unknown gas mixtures, measured values can not be clearly converted with response factors. The relative standard deviation of the individual response factors with respect to the mean value of all response factors for hydrocarbons (corresponds approximately to the measurement uncertainty in the measurement of unknown gas mixtures) should not exceed +/- 15% according to German TA-Luft.
The most common definition is the carbon related response factor relative to propane:Rf, x = Ac / Cc, x (for calibration to mgC / m3) (1)
with Rf, x = carbon-related response factor of substance X relative to propane
with AC = FID reading in mgC /m3 when measuring feed X (FID previously calibrated with propane conversion factor: 1 ppm propane = 1.61 mgC /m3 at standard conditions (1013 mbar, 0 ° C))
with Cc, x = carbon (mass) concentration in mgC /m3 of the supplied substance X. An illustration:
The reaction factor (multiplied by a factor of 100) gives the percentage of one carbon atom of molecule X as compared to one carbon atom of the propane molecule (with which the FID was calibrated). A response factor of 0.5 means that only half of the true value of a substance is measured. A correction is therefore required.
By transforming the above formula (1), we obtain:Cc, x = Ac / fRC, x (for calibration to mgC / m3) (1a)
This allows the conversion of FID displays into actual concentration values.
The following table contains a selection of response factors using the example of a Testa 2010T FID:
|Type of substance
Reaction factors are ideally close to 1.00. If all substances to be measured have a response factor of 1, the response factor should not be taken into calculation.Another example:
The measurement of ethanol-containing exhaust air provides a measured value of 95 mgC /m3. The FID was calibrated with mg propane at mgC /m3 prior to measurement.
AC = 95 mgC / m3
fRC, ethanol = 0.71
used in (1a)
Cm³, x = 95 mgC /m³ / 0.71 = 133 mgC /m³Result:
The ethanol-containing exhaust air has a carbon mass concentration of 133 mgC /m3 under standard conditions.
If the FID is calibrated to ppm then the same numerical values apply to response factors; however, the formula for the calculation is different:fRC, x = (Av * nB) / (Cv, X * nX) (for calibration to ppm) (2)
with fRC, x = carbon-related response factor of substance X relative to propane
Av = FID indication in ppm (where the FID was previously calibrated with Propane on ppm)
Cv, x = volume concentration in ppm of the added substance
nB = carbon number of the reference component (= propane)
nX = carbon number of substance X
Transforming (2) yields a formula for converting the FID displayCv, x = (Av * nB) / (fRC, X * nX) (for calibration to ppm) (2a) Example:
The measurement of benzene-containing exhaust air provides a reading of 37 ppm. The FID was calibrated to ppm propane before measurement.
AV = 37 ppm
fRC, benzene = 1.04
nPropan = 3
nBenzol = 6
used in (2a):
Cv, x = (37 ppm x 3) / (1.04 x 6) = 17.8 ppm benzeneResult:
The exhaust air has a benzene concentration of 17.8 ppm. Oxygen Interference
Differential oxygen content in the calibration gas, this results in a measurement error. At higher oxygen content in the sample gas, the measurement signal is too low, at low oxygen content too high. All Testa FIDs have an oxygen cross sensitivity clearly below 2% of MBE when using pure H2 as fuel gas! Rule of thumb:
Drop of the oxygen content in the sample gas by 1% by volume causes about 1-2% relative increase in the FID.
An oxygen change by 10 Vol.% (Previous combustion exhaust gases) already gives 10 - 20% measurement error!This cross-sensitivity can be compensated by the following measures:
It uses a fuel gas mixture of hydrogen (40 vol .-%) and helium (60 vol .-%) - commercially available as Ultramix often. In addition, the change in various detector parameters and the supply of other inert gases (makeup gases) such as xenon, helium or argon causes a significant reduction in oxygen cross sensitivity.
Important: The possible influence of the oxygen cross-sensitivity on an FID must be considered again when comparing measured values of different measuring devices! There are FID devices that have such high oxygen interference that a parallel oxygen reading is recommended to compensate for O2 cross sensitivity as a function of oxygen content.Condition of the sample gas
The measured value is indicated either in "ppm" or "mgC /m3". The second unit refers to moist sample gas under standard conditions (0 ° C, 1013 mbar). However, mass concentrations are pressure and temperature dependent. If the concentration is to be specified under other pressure or temperature conditions, these must be converted according to the gas laws.
An FID measures "wet", what means that the present measuring gas humidity does not want to be removed either during sampling or during the preparation of the sample gas by drying (gas cooler) or when calculating the measured raw-signal.
However, if the measurement result is to be given "dry" under standard conditions, then the moisture at the sampling location must be measured parallel and the HC signal must be corrected. After measurements in the high measuring ranges, absolutely exact measured values can generally not be expected in the first measuring range without longer periods of flushing the sample gas paths with clean air or nitrogen (heated up if possible).
The purging duration depends on the type of sample gas (adsorption behavior), the concentration and the duration of the measurement. Usually 2-5 minutes are sufficient.
In extreme cases (contamination by oil vapors, etc.), however, several hours of flushing time may be necessary!
On the Testa PC program or on the screen graphics, the rinsing effect can be observed well. Note the linearity range
The FID measuring principle is characterized by a (physically) linear characteristic over several decades. In the standard version, most FID analyzers are optimized in the measuring ranges up to 10,000 ppm in terms of linearity and detection limit. The vast majority of applications fall into this concentration range. Thus, in the measuring range up to 10 ppm still measurements can be carried out with a linear characteristic curve. The Testa iFid Product line is an integrated linearity optimization, at the factory and at each service done by gasdivider.
From 10,000 ppm to 100,000 ppm, the characteristic curve is usually non-linear. By multipoint calibration of this measuring range, the linearity error can be compensated by algorithm.
In this case, there is another possibility to vary the detector parameter and thus to linearize the characteristic. (The measurement range up to 100,000 ppm of propane can also be calibrated with a one-point calibration.)Note:
Calibration gases in high concentration range are usually only available with nitrogen as the base gas. If the oxygen cross sensitivity is not compensated at the analyzer, this influence must be considered during the calibration!
Process parameters describe the properties of a measuring method and its performance.
For the following process characteristics the minimum requirements according to the "Guidelines on the suitability test, the installation, the calibration and the maintenance of measuring devices for continuous emission measurements" of the Federal Ministry for the Environment are given: Linearity:
The deviation from a linear device characteristic (calibration curve) should be less than 2% of the full scale value.Detection limit:
The Detection limit still has a clearly demonstrable concentration of hydrocarbons. They should be less than 2% of the most sensitive full scale value. With special FID a dection limit of approx. 10 ppb (parts per billion = 1 billionth!) can be achieved – maybe in future.Response time (t-90 time):
The response time is the time between the injection of sample gas and the seen 90% of the this sample gas. This should be done within less then 20 seconds. With Testa FIDs t-90 times of less than 1 second can be realized from the back of the device.Temperature dependence of the zero point display:
This should be less than 2% of the full scale value for ambient temperature changes between 0 - 45 ° C.Temperature dependence of the sensitivity:
This should be less than 2% of the full scale value for ambient temperature changes between 0 - 45 ° C.
The sensitivity of a FID is, among other things, a function of the nozzle, burner and (suction) electrode geometry, as well as the applied suction voltage and the flows of combustion air, fuel gas and sample. On the various influences by the arrangement and shape of the burner interior can not be discussed here.Detection voltage
The FID should be operated in the saturation range of the current-voltage characteristic at approx. 200 V.Fuel gas flow
The sensitivity of the FID is maximized by varying the fuel gas flow. The detector is operated at this sensitivity maximum. As fuel gas, hydrogen of purity 5.0 (= 99.999% purity) is normally used. Typical flow values are 30 - 150 ml / min.Combustion air flow
As the combustion air flow increases, the detector sensitivity increases to a plateau. The fuel gas flow is adjusted at this plateau. As combustion air there will be used hydrocarbon-free air. Typical flow values are 30 - 50 l /h.Sample flow
As the same time the sample flow increases, the sensitivity increases. However, this happens at the expense of the linearity. Thus, a FID with low sample flow can be linearized at the expense of sensitivity over several decades or made highly sensitive with high sample flow at the expense of linearity for small ranges. Typical flow values are 5-50 ml/min.
Conversion formulas for FID measurement
- The mass concentration values refer to "moist" sample gas under standard conditions (0°C and 1013 mbar). If the concentration is to be stated under other pressure or temperature conditions, it must be converted according to the gas laws.
- FID = flame ionization detector for measuring hydrocarbons
- RF = Response Factor with Relation on Propane (RF = Response Factor with Relation on Propane).
- Molar volume of propane = 22.4 l/mol under standard conditions (0°C and 1013 mbar).
FID measurement method
The FID method is based on the effect that in case you bring organic compounds into a very pure hydrogen-flame, there will be seen electric charged elements called ions. Therefore, the name Flame Ionization
and the name of the associated instrument, which is called FlammenIonizationsDetector (FID
), is used.
After ionization, organically bound amounts in the hydrogen flame of the FIDs are discharged to these resulting ions at an electron pair by means of an applied suction voltage. The thereby flowing current is measured by means of a high-sensitivity DC amplifier and displayed. It is in a wide range proportional to the number of parts per unit time in the flame. The molecular structure (single and double bond, number and type of phenomena, chain length and ring structure) significantly influences the oxidation properties of the carbon and thus the size of the detector signal. Thus, organic compounds with oxygen as a heteroatom (generally with significantly reduced sensitivity) are displayed. The different display sensitivities to different organic compounds are expressed in response factors. These are substance- and device-specific (depending on nozzle shape, electrode, combustion chamber and combustion air mixture) and must not be transferred to other FIDs.
Examples for response factors
The FID selectively addresses the group of hydrocarbons - more specifically the organic carbon as part of hydrocarbon molecules. As a first approximation, the FID signal is proportional to the number of c-atoms of hydrocarbons in the sample gas. Depending on the molecular structure, the FID presents also a different response, which is quantified by so-called "response factors". Response factors can be defined differently. The most common definition is:
Hydrocarbon-related response factor Rf B (X) of the substance X with respect to the reference substance B:RF B (X) = (aX / aB) / (Cc, X / Cc, B)
with aX and aB = FID signal of the substance X and the reference substance B
and Cc, X = mass concentration of substance X or B contain carbon in mgC /m3The reference substance is usually propane (rarely methane)
Response Facts must be determined for each device individually, as they depend on the gas flows and the detector geometry.
Since ions are formed in the plasma due to oxidation processes, preoxidized hydrocarbons contribute less to the ion current. Their response factors - based on non-oxidized n-alkanes propane - are generally lower or lower than 1. The reference component is assigned by defining the value Rf = 1.00. The higher the oxidation state of the C-atom, the lower the "response" of this substance.
Please take a look at our extensive list of response factors
in the download area
Literature about the topic FID
-Gans, W., Baumbach, G.: Kalibrierverfahren zur quantitativen Bestimmung flüchtiger organischer Substanzen in Abluft und Abgasen mit dem Flammenionisationsdetektoren. Fortschrittberichte VDI Reihe 15 Nr. 32 Düsseldorf VDI-Verlag 1985
-Ackman, R.G.: Fundamental Groups in the Response of Flame Ionization Detectors to Oxigenated Aliphatic Hydrocarbons. Journal of Gaschromatographie, June (1964), S. 173-179.
-Volkswagenwerk AG: Improving the Method of Hydrocarbon Analysis, Wolfsburg 1980
-Jentzsch, D., Otte, E.: Methoden zur Analyse in der Chemie. Band 14 Detektoren in der Gasromatographie. Akademische Verlagsgesellschaft Frankfurt a. M. 1970
-Leibnitz, E.; Struppe, G.: Handbuch der Gaschromatographie. Akademische
Verlagsgesellschaft (Geest & Portig) Leipzig 1984
-Jockel, W.: Leistungsfähigkeit von FID zur Emissionsüberwachung organischer Verbindungen Staub-Reinhaltung der Luft 43 (1983) Nr . 7, S. 283/90
-Jockel, W.: Stand der Gesamtkohlenstoff-Messung im Abgas von Abfallverbrennungsanlagen Staub-Reinhaltung der Luft 49 (1989). S 221-225
-Dobson, J. G,: Anwendung von FID für die Analyse kontinuierlicher Prozesse ATM (Februar 1966), S. R25 - R44
-Bühne , K.-W.: Vergleichende Untersuchungen mit Messeinrichtungen zur fortlaufenden Messung organischer Verbindungen als Gesamtkohlenstoff, Staub-Reinhaltung der Luft 38 (1978), Nr 3, S. 110/11
-TÜV-Rheinland: Bericht über das Forschungsvorhaben: Vergleichende Untersuchungen über die Eignung von registrierenden Messgeräten zur Überwachung der Emissionen organischer Verbindungen als Gesamtkohlenstoff. Bericht Nr 936/804006 vom 31.01.1977
-RdSchr. d BMU v. 01.03.1990-IGI2 - 556 134/4 - Betr.: Richtlinien über die Eignungsprüfung, den Einbau, die Kalibrierung und die Wartung von Messeinrichtungen im kontinuierliche Emissionsmessungen (GMBI 1990 Nr. 12, S . 226)
-DIN-ISO 6879: Luftbeschaffenheit. Verfahrenskenngrößen und verwandte Begriffe Messverfahren zur Messung der Luftbeschaffenheit.
-DIN EN 12619 Emissionen aus stationären Quellen, Bestimmungen der Massenkonzentration des gesamten organisch gebundenen Kohlenstoffs in geringen Konzentrationen in Abgasen, Kontinuierliches Verfahren unter Verwendung eines Flammenionisationsdektors; 09/99
-DIN EN 13526 Emissionen aus stationären Quellen, Bestimmungen der Massenkonzentration des gesamten organisch gebundenen Kohlenstoffs in hohen Konzentrationen in Abgasen, Kontinuierliches Verfahren unter Verwendung eines Flammenionisationsdektors; 05/02
-VDI 3481 Bl. 6 Messen gasförmiger Emissionen. Anwendung C-Summenverfahren Auswahl und Anwendung von C-Summenverfahren.
-VDI 3481 Bl. 1 Messen gasförmiger Emissionen. Messen der Kohlenwasserstoffkonzentration; Flammen-Ionisations-Detektor (FID)
-VDI 3481 Bl. 2 Messen gasförmiger Emissionen. Bestimmung des durch Adsorption an Kiesgel erfassbaren organisch gebundenen Kohlenstoffs in Abgasen.
-VDI 3481 Bl. 3 Messen gasförmiger Emissionen. Messen von flüchtigem organischen Verbindungen, insbesondere Lösemitteln, mit dem Flammenionisationsdetektor(FID)
-VDI 3950 Bl. 1 Kalibrierung automatischer Messeinrichtungen.
-VDI 2449 Bl. 1 Prüfkriterien von Messverfahren. Datenblatt zur Kennzeichnung von Analysenverfahren für Gas-Immissionsmessungen.
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