[en] In a series of industrial processes ultrafine aerosol particles are generated (diameter < 0.02 μm). It is therfore vital to have techniques not only for the production of monodispersed, ultrafine particles but also for their detection. The developed generator operates according to the principle of atomizing salt solutions in a hydrogen flame. Quantity and concentration of the metallic salt solution sprayed into the hydrogen flame determine diameter and size distribution of the produced metallic oxide particles. More than 98% of the particles have a diameter < 0.008 μm. The particle number is measured by Aitken nuclei counter, that of the particle concentration by radioactive labeling and measuring of the activity. (orig.)

[en] A spinning top aerosol generator has been used to generate monodisperse methylene blue particles in the size range from 0.6 to 6 μm. The number concentrations of these aerosols have been determined by means of an optical particle counter and compared with the equivalent measurements obtained by filter collection and microscopy. (author)

[en] An instrument was designed for measuring sodium aerosols concentrations using flame photometry. The instrument meets the requirements for long-term measurement. Sodium particles are heated in a hydrogen flame to the temperature required for excitation and they emit the characteristic yellow coloured flame. The hydrogen flame light containing sodium particles does not pass through a monochromatic spectral filter for the sodium spectral line to the pohotomultiplier cathode whose current is proportional to the intensity of the impacting light. The electronic part of the instrument consisting of replaceable modules is built using units available on the home market. (Kr)

[en] The investigation of the throw of the graphite aerosols and dusts in the air flow at different height has been made during 6 years. The measuring of the transportation parameters was carried out with the use of ground and air means of objective control (optical, laser, radio locator). It was revealed that the conditions of transboundary transportation of aerosols by air flow was in god agreement with barometric relief. It permits to use obtained information for prediction of aerosols transportation of the radionuclides storms

[en] Standard monodisperse aerosols are required for the calibration of aerosol particle size analysers. A commercially available vibrating orifice aerosol generator has been commissioned to produce liquid and solid aerosols in the particle size range 2-30 μm. Various problems have been experienced during the operation of this equipment, particularly regarding the reliable generation of solid aerosols. The performance of the generator is reviewed in terms of the liquid feed, the orifice-jet requirements, the solvent evaporation and the solid aerosol drying characteristics. (orig.)

[en] Many on-site tests are mainly tests of holes or sealing leaks as they employ heterodisperse clouds of particles, significant fractions of which are too large for penetration of intact HEPA filters. If it can be assumed that the filter material, when intact, is of high efficiency towards submicrometre particles, it is at least arguable that these types of test are adequate and that laboratory or factory rig tests are unnecessary. For detection of holes in systems the aerosol size is relatively unimportant and it is found in practice that different size distributions give similar results. There is, however, likely to be a need for on-site tests which give a true value - that is, of filter penetration plus leakage - when the system is challenged with submicrometre aerosols. An example appears to be in processing plutonium. We may therefore address ourselves to two types of on-site assessment. Firstly to search for holes (leakages) and secondly to measure the passage of submicrometre particles. Improvements in the first type are likely to be concerned with mixing and sampling of aerosols while the second, additionally, requires investigation into generation and detection methods. In all tests it is important that results are reliable. This involves thorough mixing of aerosol both upstream and downstream of the filter. Unfortunately few systems have been designed for ease of on-site tests and operators have to employ makeshift devices, often in cramped and uncomfortable situations. This paper gives examples of the need for mixing and sampling and of the penetration of intact filters by aerosols of different size distributions. Tests in common use are outlined, together with problems and likely developments. (author)

[en] The subject of aerosols is discussed extensively under the following chapter headings: objectives, organization, and applications; aerosol generation; dynamic behavior of aerosols; optical properties of aerosols; sampling and particle-size measurement; and summary tables and graphs for static and dynamic characteristics of aerosol systems. A glossary, nomenclature, and index are included

[en] Well defined standard aerosols are very important for the validation and evaluation of particle size analysis equipment. An important requirement for an aerosol studies laboratory is the ability to generate monodispersed aerosols in the 0.1 to 10 micron range to calibrate air samplers, and in particular the popular cascade impactors. The May spinning-top aerosol generator has been adapted to generate monodisperse solid aerosols in the size range 1 - 6 micron with a standard deviation of 1.1. The problems experienced during this development work are described in detail. The aerosols produced were studied by means of optical microscopy and the scanning electron microscope (SEM), and a comparison of these two techniques has been made. (U.K.)

[en] Andersen Mark-II and California Measurements PC-2 quartz-crystal (QCM) cascade impactors have been calibrated with monodisperse aerosol particles. Both the Andersen and QCM impactors were determined to be reliable instruments: the advantage of the QCM impactor is that real-time monitoring of aerosol behaviour is possible, using short measurement times. However, care is needed to interpret the QCM data if this instrument is used to sample aerosols that carry an unknown or significant electrostatic charge. (author)

[en] Estimating the filter efficiency of HEPA filter units using DOP aerosols is a proven technique which is being extensively used for the in-situ testing of single filters and filter banks in active facilities. A dedicated, state of the art facility for testing various sizes of HEPA filter units is available at Indira Gandhi Centre for Atomic Research under Radiological Safety Division. Feasibility studies were carried out by incorporating a few additional arrangements in the existing filter test facility to explore the possibility of its use for testing the collection efficiency CAM filter heads. The modifications did not affect or hinder the intended utility of the filter test facility. The modifications done and the experimental technique are discussed in this paper