Dust measurement

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As dust measurement is used to measure the mass or number of concentration is dust-like impurities referred moving or static gases. Various measuring methods are available for dust measurement. It is carried out for both emission and immission monitoring. Dust measurements are also carried out to check and characterize dedusting devices such as filters . The measurement results are usually given in mass per volume, but the dust mass and number of particles can also be related to other sizes.

Basics

The measurement of dusts in still air or in flowing gases can be done due to different needs. Operators of plants that require approval are often obliged to carry out regular or even continuous measurements of the air pollutants emitted , including dust. Approval notifications and ordinances contain limit values ​​that must be observed. If this is exceeded, the system operator is required to take measures to reduce emissions. Dust measurement is usually required for incineration processes in plants that require approval. In Germany, the Federal Environment Agency publishes a list of suitability-tested continuously working dust measuring devices on its website.

Air hygiene monitoring system Lower Saxony : measuring container in Emden for measuring the background concentration

The immission measurement of dust differentiates between airborne dust and dust precipitation . Both are monitored by the authorities responsible for immission control, which operate measuring networks to record immission of air pollutants to monitor air quality. The recording of both the suspended dust concentration and the dust precipitation serves to characterize the immission situation. As a so-called indirect method for determining emissions, suspended particulate matter immission measurements also allow statements to be made about diffuse emissions by means of back- source calculation .

To monitor the protection of employees, measurements of pollutants, including dust, are often carried out at particularly exposed workplaces. If control or limit values ​​are exceeded, countermeasures must be taken. These can be both active (source extraction) and passive (protective clothing).

Dust measurements are also carried out with the aid of test aerosols to determine the efficiency of dust extractors .

The particle sizes in the dust measurement range between a few nm and more than 100 µm.

history

As early as the 1870s, the French meteorologist Gaston Tissandier collected the dust on two square meters of paper to determine the size, shape and number of the particles. At about the same time, John Tyndall had observed the scattering of light on particles. The Tyndalloscope based on the Tyndall effect as a measuring device was not established until the mid-1930s. In 1879 John Aitken developed the first condensation nucleus counter. In 1898 the French agricultural engineer Maximilien Ringelmann published a method for assessing exhaust plumes. The Ringelmann scale contained gray values ​​that were compared with the opacity of the exhaust plume. Around 1900, small tubes filled with sugar were used at South African mine workplaces, through which the dust-laden air was sucked in order to be analyzed afterwards. Important devices for measuring dust in the first half of the 20th century were the Konimeter , which was developed in 1919, and the thermal precipitator , which was introduced into dust measurement technology in 1935.

The systematic gravimetric dust measurement started in 1950; a standard was implemented in 1971. Dust measurement methods based on the principle of inertial force separation were also used in the 1950s . In the 1960s, dust measuring devices were developed that were based on the principle of attenuating beta rays ( radiometric dust measurement ).

With the introduction of the PM10 standard by the Environmental Protection Agency in July 1987, attention was drawn to the particle size in environmental protection. A definition of fine dust has existed in occupational safety since 1959 with the Johannesburg Convention .

Measurement method

The requirements for measurement methods for emission and immission measurement differ significantly. The main difference lies in the concentration ranges. Samples often still need to be processed when measuring emissions . When measuring emissions, reference values ​​such as pressure and temperature often have to be determined.

A differentiating criterion in the dust measurement process is the question of how the dust-laden gas is fed to the measurement device. Passive collectors use diffusion processes so that the dust reaches an acceptor surface. In active processes, a compressor is used to generate a flow that leads the gas to be sampled to the measuring device. It should be noted that the compressors can lead to considerable noise pollution.

When measuring dust emissions, a distinction must also be made as to whether the sampling takes place extractive or in situ . With extractive sampling, a partial flow is isokinetically taken from the exhaust gas and fed to the measuring device. A network measurement must be carried out for measurement cross-sections that are at least 0.1 m 2 .

In the common dust measurement methods, different physical properties of the dust to be measured are used to output a dust concentration, often given in mass per volume. In addition to the density of the dust particles, their optical properties are used.

Filter strips with deposited dust

In measuring methods such as gravimetric or radiometric dust measurement , the particles contained in the gas are separated on a filter . The filter with the separated dust is then analyzed. In addition to weighing or radiometric fluoroscopy, this analysis can also include a chemical analysis .

Common measurement methods are listed in the table below.

Measuring device / measuring method Brief description particularities
Bergerhoff method Passive collection of dust deposits in a beaker and subsequent weighing of the acceptor surface Use for dust precipitation measurement according to TA Luft and LRV
Gravimetric dust measurement Isokinetic suction of a partial flow of an exhaust gas and separation of the dust contained therein on a filter with its subsequent weighing Procedure for the calibration of automatic dust measuring devices
Cascade impactor fractional deposition of particles on acceptor surfaces and their subsequent evaluation Two-stage cascade impactors are used to determine the mass concentrations of PM 10 and PM 2.5 as well as fine quartz dust in the exhaust gas
Conimeter Transport of the dust-laden air through a gap with deposition of the dust on an adhesive surface and its subsequent microscopic evaluation an apparatus called the “aeroscope” comparable to the later Konimeter was developed as early as 1878
Photometric dust measurement Measurement of light attenuation or scattered light in a dust-laden gas Scattered light measuring devices are used when the weakening of the penetrating light beam is too small
Radiometric dust measurement Application of dust to a filter and subsequent irradiation with a beta emitter can be used for emission and immission measurements
TEOM Impact of dust on a vibrating system, the natural frequency of which changes as a result direct output of dust concentrations possible
Thermal precipitator Deposition of dust on a collecting plate based on thermophoresis with subsequent microscopic evaluation Particles with a diameter of less than 1 µm can be quantified very well with the thermal precipitator

In the case of measuring devices such as the high-volume sampler and the low-volume sampler , which are used to record suspended dust, dust is applied to a filter, as is the case with gravimetric dust measurement, and then analyzed or weighed.

Comparability of the results

As early as the 1950s it was established that results obtained with different dust measurement methods are only partially comparable. That is why there was already a requirement at that time that a dust measuring device should output the same measurement results with acceptable tolerances under comparable conditions . Currently, the type of measuring equipment used and the sampling conditions for dust emission measurement still have a significant influence on the measurement result. There are efforts to develop conversion factors for measurement results from older gravimetric dust measurements. The comparability of the results of measurement processes is also checked by means of round robin tests .

Sources of error

The potential sources of error depend on the type of measurement task and the sampling. In the case of emission measurements, non- isokinetic sampling can lead to errors if too few or too many particles are deposited on the filter. Other possible sources of error are weighing errors and dust deposits outside the filter. Leakages in the measuring equipment can also lead to incorrect measuring results.

With extractive sampling, particles can be deposited in the pipeline leading to the measuring device. This leads to measurement results that are too low. When taking extractive samples, it must also be ensured that the volume or the volume flow extracted is in an appropriate ratio to the total volume. In the case of measurements in the interior, guideline VDI 4300 Part 11 explicitly states that the volume sucked in by the dust measuring device must not exceed a certain proportion of the exchanged volume or the volume of the room.

The soiling of optical interfaces can lead to falsified measurement results during photometric dust measurement. That is why extinction measurements are usually carried out with a second light beam from the same source, which shines through a dust-free reference path. The attenuation of the measuring beam is then only related to the reference beam. Another possibility to counteract the falsification of the measurement results is to apply filtered purging air to the interfaces.

Cross-sensitivities can occur when measuring quartz fine dust if mineral admixtures are present.

Limit value derivation

Limit values are used to limit pollutants in the atmosphere. They are defined with the aim of avoiding or reducing harmful effects on people and the environment. In comparison to individual chemical substances, however, the introduction of limit values ​​for dust pollution is much more difficult, since not only can their chemical composition differ with dusts, but also their size and structure; The origin and formation of the particles are of great importance. In the case of workplaces , there is also the fact that dust concentrations are subject to strong fluctuations over the working hours . That is why the derivation of limit values ​​on the basis of measured values ​​from dust measurements is usually conservative . For substances for which no effects are to be expected below a certain dose ( NOEL ), a safety factor is used to determine the limit value. In 1997, for example, the general dust limit value set by the German Research Foundation was set lower than the value extrapolated from animal experiments .

literature

  • Günter Baumbach: Air pollution control. Springer-Verlag Berlin, Heidelberg, New York, 2nd edition 1992, ISBN 3-540-55078-X , pp. 160-167, 206-224.
  • VDI 2066 sheet 1: 2006-11 measurement of particles; Dust measurements in flowing gases; Gravimetric determination of dust load (Particulate matter measurement; Dust measurement in flowing gases; Gravimetric determination of dust load). Beuth Verlag, Berlin. ( Summary and table of contents online )

Individual evidence

  1. ↑ Federal Environment Agency: Suitability-tested continuously operating emission measuring devices , accessed on September 23, 2018
  2. ^ Franz Joseph Dreyhaupt (ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , pp. 1050-1051.
  3. ^ Franz Joseph Dreyhaupt (ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , pp. 629-630.
  4. ↑ VDI 3790 sheet 1: 2015-07 environmental meteorology ; Emissions of gases, odors and dusts from diffuse sources; Basics (Environmental meteorology; Emissions of gases, odors and dusts from diffuse sources; Fundamentals). Beuth Verlag, Berlin, p. 16.
  5. ↑ VDI 4285 sheet 3: 2015-11 Metrological determination of emissions from diffuse sources; Quantification of diffusive emissions from industrial plants including agricultural sources (Determination of diffusive emissions by measurements; Quantification of diffusive emissions of fine dust from industrial plants including agricultural sources). Beuth Verlag, Berlin, p. 9.
  6. ↑ VDI 3491 sheet 1: 2016-07 Measurement of particles; Manufacturing process for test aerosols; Basics and overview (Measurement of particles; Methods for generating test aerosols; Principles and overview) . Beuth Verlag, Berlin, p. 3.
  7. ↑ VDI 2463 sheet 1: 1999-11 measurement of particles; Gravimetric determination of the mass concentration of particles in the outside air; Basics (Particulate matter measurement; Gravimetric determination of mass concentration of suspended particulate matter in ambient air; General principles). Beuth Verlag, Berlin, p. 5.
  8. ↑ a b c d e f Carsten Möhlmann: Dust measurement technology - then until now. In: Hazardous substances - cleanliness. Air . 65, No. 5, 2005, ISSN  0949-8036 , pp. 191-194.
  9. ↑ Kvetoslav Spurny (Ed.): Analytical Chemistry of Aerosols: Science and Technology. CRC Press, Lewis Publishers, New York 1999, ISBN 1-56670-040-X , p. 4.
  10. ^ Gustav Kühnen, Wolfgang Pfeiffer, Edgar Rudolf: Development of the dust measurement technology at the workplace. In: Dust - cleanliness. Air . 46, No. 4, 1986, ISSN  0949-8036 , pp. 177-181.
  11. ^ Franz Joseph Dreyhaupt (ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 981.
  12. ↑ Karlheinz Schmitt: Basic investigations on the thermal precipitator. In: dust. 19, No. 12, 1959, pp. 416-421.
  13. ↑ a b Karlheinz Guldner, Dirk Dahmann, Markus Mattenklott, H.-H. Fricke, Othmar Steinig, Johannes Böhm: Development of conversion factors for results of early gravimetric dust measurements. In: Hazardous substances - cleanliness. Air. 71, No. 5, 2011, ISSN  0949-8036 , pp. 191-198.
  14. ↑ J. Olaf: Dust measurement method. In: dust. 19, No. 6, 1959, pp. 221-226.
  15. ↑ a b Ludwig Düwel: State of the art in the development of control measuring devices for continuous monitoring of dust emissions. In: Dust - cleanliness. Air. 28, No. 3, 1968, pp. 119-127.
  16. ↑ James H. Vincent: Aerosol Sampling - Science, Standards, Instrumentation and Applications . John Wiley & Sons, Chichester 2007, ISBN 978-0-470-02725-7 , p. 432.
  17. ^ Franz Joseph Dreyhaupt (ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 981.
  18. ^ Günter Baumbach: Air pollution control. Springer-Verlag Berlin, Heidelberg, New York, 2nd edition 1992, ISBN 3-540-55078-X , p. 164.
  19. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 1116.
  20. ↑ VDI 2119: 2013-06 Measurement of Immissions; Sampling of atmospheric particles> 2.5 µm on an acceptor surface with the passive collector Sigma-2; Light microscopic characterization and calculation of the number sedimentation rate and the mass concentration (ambient air measurements; Sampling of atmospheric particles> 2.5 µm on an acceptor surface using the Sigma-2 passive sampler; Characterization by optical microscopy and calculation of number settling rate and mass concentration). Beuth Verlag, Berlin, p. 9.
  21. ↑ Dieter Bake, Lothar Laskus: Development and use of an easily transportable filter device for airborne dust measurements . In: Dust - cleanliness. Air . 38, No. 1, 1978, ISSN  0949-8036 , pp. 21-24.
  22. ↑ Jens Linnenberg, Georg Schwedt, Klaus Broschinski: Long-term sampling of particle-bound and filter-permeable heavy metal emissions in pure gases from technical furnaces. In: Hazardous substances - cleanliness. Air . 60, No. 5, 2000, ISSN  0949-8036 , pp. 223-227.
  23. ↑ VDI 3951: 2013-09 Overview on relevant regulations on the performance of emission measurements. Beuth Verlag, Berlin, p. 14.
  24. ↑ VDI 4320 sheet 2: 2012-01 Measurement of atmospheric deposition; Determination of the dust deposition according to the Bergerhoff method (Measurement of atmospheric depositions; Determination of the dust deposition according to the Bergerhoff method). Beuth Verlag, Berlin, p. 2.
  25. ↑ VDI 2066 sheet 1: 2006-11 measurement of particles; Dust measurements in flowing gases; Gravimetric determination of dust load (Particulate matter measurement; Dust measurement in flowing gases; Gravimetric determination of dust load). Beuth Verlag, Berlin, p. 17.
  26. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 586.
  27. ↑ VDI 2066 sheet 5: 1994-11 measurement of particles; Dust measurement in flowing gases; Fractional dust measurement using the Impaction Method - Cascade Impactor (Particulate Matter Measurement; Dust Measurement in Flowing Gases; Particle Size Selective Measurement by Impaction Method - Cascade Impactor). Beuth Verlag, Berlin, pp. 3-4.
  28. ↑ DIN EN ISO 23210: 2009-12 Emissions from stationary sources; Determination of the mass concentration of PM10 / PM2.5 in the exhaust gas; Measurement at low concentrations with impactors (ISO 23210: 2009); German version EN ISO 23210: 2009. Beuth Verlag, Berlin, p. 13.
  29. ↑ VDI 2066 sheet 11: 2018-05 Measurement of particles; Dust measurement in flowing gases; Measurement of emissions of crystalline silicon dioxide (quartz and cristobalite) in the PM 4 fraction (Particulate matter measurement; Dust measurement in flowing gases; Measurement of emissions of crystalline silicon dioxide (quartz and cristobalite) in the PM 4 fraction). Beuth Verlag, Berlin, p. 10.
  30. ↑ VDI 2266 sheet 2: 1968-08 Measurement of the dust concentration at the workplace; Measurement of particle number; Measure with the Konimeter. VDI publishing house, Düsseldorf. P. 2.
  31. ↑ a b c Karl-Wilhelm Bühne: Investigations into the directional dependence of photoelectric smoke density measuring devices. In: Dust - cleanliness. Air . 31, No. 7, 1971, pp. 285-290.
  32. ^ Franz Joseph Dreyhaupt (ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , pp. 1118–1119.
  33. ↑ Heinrich Dresia, Franz Spohr: Possible uses and errors of radiometric dust measurement for monitoring emission, immission and workplaces. In: Dust - cleanliness. Air . 38, No. 11, 1978, ISSN  0949-8036 , pp. 431-435.
  34. ↑ James H. Vincent: Aerosol Sampling - Science, Standards, Instrumentation and Applications . John Wiley & Sons, Chichester 2007, ISBN 978-0-470-02725-7 , p. 381.
  35. ↑ Carsten Möhlmann, Johannes Pelzer, Albert Hellmann, Jens Niklas: Metrological determination of ultrafine and nanoparticles in mechanical processing of nanomaterials and their composites. In: Hazardous substances - cleanliness. Air. 72, No. 11/12, 2012, ISSN  0949-8036 , pp. 463-465.
  36. ↑ Sheldon Kay Friedlander : Smoke, Dust, and Haze - Fundamentals of Aerosol Dynamics . John Wiley & Sons, New York 1977, ISBN 0-471-01468-0 , p. 43.
  37. ↑ VDI 2266 sheet 1: 1968-08 Measurement of the dust concentration at the workplace; Measurement of particle number; Measure with the thermal precipitator. VDI-Verlag Düsseldorf, p. 2.
  38. ↑ Walter Lorenz Hartmann: Investigations into the comparability of the results of different dust measurement methods. In: dust. 19, No. 10, 1959, pp. 345-351.
  39. ↑ D. Hasenclever: Investigations into the suitability of various dust measuring devices for operational measurement of mineral dusts. In: dust. No. 41, 1955, pp. 388-435.
  40. ↑ Roland Régnier, Denis Bémer, Yves Morèle: Effect of the sampling system on the measured particle concentration in ventilation ducts. In: Hazardous substances - cleanliness. Air. 73, No. 1/2, 2013, ISSN  0949-8036 , pp. 49-55.
  41. ^ Günter Baumbach: Air pollution control. Springer-Verlag Berlin, Heidelberg, New York, 2nd edition 1992, ISBN 3-540-55078-X , p. 252.
  42. ↑ Christoph Sager, Frank Schmidt, Klaus Gerhard Schmidt: Investigations on particle deposition in sampling lines due to various transport mechanisms. In: Hazardous substances - cleanliness. Air. 61, No. 5, 2001, ISSN  0949-8036 , pp. 207-211.
  43. ↑ VDI 4300 sheet 11: 2013-12 Measurement of indoor air pollution ; Measurement strategy for the detection of airborne particles in the interior; PM 2.5 fraction (Measurement of indoor air pollution; Measurement strategies for determination of airborne particles in indoor environment; Particles PM 2.5 fraction). Beuth Verlag, Berlin, p. 23.
  44. ↑ VDI 2066 sheet 11: 2018-05 Measurement of particles; Dust measurement in flowing gases; Measurement of emissions of crystalline silicon dioxide (quartz and cristobalite) in the PM 4 fraction (Particulate matter measurement; Dust measurement in flowing gases; Measurement of emissions of crystalline silicon dioxide (quartz and cristobalite) in the PM 4 fraction). Beuth Verlag, Berlin, p. 20.
  45. ^ A b Franz Joseph Dreyhaupt (Ed.): VDI-Lexikon Umwelttechnik. VDI-Verlag Düsseldorf 1994, ISBN 3-18-400891-6 , p. 587.
  46. ↑ DIN EN 16450: 2017-07 outside air; Automatic measuring devices for determining the dust concentration (PM10; PM2.5); German version EN 16450: 2017. Beuth Verlag, Berlin, p. 8.
  47. ↑ VDI 3459 sheet 1: 2017-11 Terminology in energy and waste management; Basics. Beuth Verlag, Berlin, p. 28.
  48. ^ Marco Steinhausen, Yi Sun: International Dust Symposium. In: Hazardous substances - cleanliness. Air. 77, No. 4, 2017, ISSN  0949-8036 , pp. 150-153.
  49. ↑ a b Frank Bochmann, Peter Morfeld: The distribution of the measured values ​​from dust measurements and their significance for the derivation of limit values. In: Hazardous substances - cleanliness. Air. 71, No. 10, 2011, ISSN  0949-8036 , pp. 419-423.
  50. ↑ Axel Barig, Helmut Blome: General dust limit value - Part 1: General. In: Hazardous substances - cleanliness. Air. 59, No. 7/8, 1999, ISSN  0949-8036 , pp. 261-265.