PROJECT
Instrument calibration
Research requiring polydisperse, high-concentration aerosol
The Model 9302 Atomizer is an aerosol generator specifically designed to align and check out laser velocimeters (LV). A supply of laboratory compressed air is connected directly to the input of its built-in pressure regulator; the pressure gauge shows the air pressure at the output side of the pressure regulator. In this aerosol generator, the compressed air expands through a small orifice (0.5 millimeter in diameter) in the form of a high velocity jet located in the jet-nozzle assembly. The jet creates an area of low pressure near the orifice which, in turn, causes the liquid in the reservoir to be sucked up into the orifice. The liquid is then broken into tiny liquid droplets and the compressed air carries the droplets through the outlet tube. To perform laser velocimeter checkout, direct the atomizer’s output tube at the point of beam-crossing. Adjust the height of the output tube by loosening the hex nut and shifting the tube up or down. The Atomizer is designed primarily for LV system checkout and should not be used to feed aerosols into a system under pressure
The Model 3076 Constant Output Atomizer, shown in Figure 1-1, generates submicrometer aerosols that can atomize most solutions or suspensions. The conventional mode of operation for the Model 3076 Atomizer is the recirculation mode. The atomizer can be modified to work in nonrecirculation mode if necessary. The number median diameter of the droplets the Atomizer generates is about 0.3 micrometer and the geometric standard deviation is less than 2.0. The mean particle size of the generated aerosol can be varied between 0.02 and 0.3 micrometer by atomizing a solution and evaporating the solvent. A common problem of conventional recirculation mode is that the solvent gradually evaporates in the Atomizer, causing the solution that remains in the reservoir bottle to become more concentrated and thus yield larger aerosol particles. A significant increase in particle size occurs within several minutes when using volatile solvents such as alcohol. Running the atomizer in nonrecirculation mode eliminates this problem by preventing the recirculation of the solution. Either an extra reservoir bottle or a syringe pump is required to set up the nonrecirculation mode. Tight tolerances are maintained for all critical dimensions of the Atomizer to ensure the accuracy of its output particle size.
The Model 3079 is a new, innovative aerosol generator that produces aerosol particles in the submicrometer range. It generates polydisperse aerosol by atomizing a solution. It will generate monodisperse particles by atomizing monodisperse particles in suspension. The mode of the particle size produced is between 0.2 and 0.3 micrometers. Particle concentration can be changed by adjusting the flow through the atomizer. The Atomizer Aerosol Generator is portable and of a very compact and rugged design. A built-in low-noise compressor provides the compressed air DES test aerosol produced by the Model 3079, measured with TSI’s Model 3936-Series Scanning Mobility Particle Sizer (SMPS)needed for the atomizing process. The Model 3079 uses a completely new atomizer head made entirely of stainless steel. The atomizer head and the glass vessel containing the solution are protected by a hinged cover that opens easily.
