Solid sampler design

Huynh CK, Vu-Duc T, Savolainen H. 1992. Design and evaluation of a solid sampler for the monitoring of airborne two-component spray painting. Am Ind Hyg Assoc J 53(3) 157-162. 

The Lee and Gieseke model (8) for predicting aerosol collection on packed beds assumes that the volume fraction, or solidity, of the packed bed approaches 5/8, and applies to the collection by the packed bed only. Since the silica gel collection tube has a volume fraction of one-half or less, and since the greater percentage of the aerosol is collected on the initial glass wool plug, the model is not applicable to our sampler design. 

The whole atomizer may be water cooled to improve precision and increase the speed of analysis. The tube is positioned in place of the burner in an atomic absorption spectrometer, so that the light passes through it. Liquid samples (5-100 mm ) are placed in the furnace, via the injection hole in the centre, often using an autosampler but occasionally using a micro-pipette with a disposable, dart-like tip. Solid samples may also be introduced in some designs, this may be achieved using special graphite boats. The sample introduction step is usually the main source of imprecision and may also be a source of contamination. The precision is improved if an autosampler is used. These samplers have been of two types automatic injectors and a type in which the sample was nebulized into the furnace prior to atomization. This latter type was far less common. 

The Polar Organic Chemical Integrative Sampler or POCIS is designed to sample water-soluble (polar or hydrophilic) organic chemicals from aqueous environments (Alvarez et al., 2004 Jones-Lepp et al., 2004 Petty et al., 2004 Alvarez et al., 2007). It consists of a solid material (sorbent) contained between two microporous... 

In the applications of gas-solid flows, measurements of particle mass fluxes, particle concentrations, gas and particle velocities, and particle aerodynamic size distributions are of utmost interest. The local particle mass flux is typically determined using the isokinetic sampling method as the first principle. With the particle velocity determined, the isokinetic sampling can also be used to directly measure the concentrations of airborne particles. For flows with extremely tiny particles such as aerosols, the particle velocity can be approximated as the same as the flow velocity. Otherwise, the particle velocity needs to be measured independently due to the slip effect between phases. In most applications of gas-solid flows, particles are polydispersed. Determination of particle size distribution hence becomes important. One typical instrument for the measurement of particle aerodynamic size distribution of particles is cascade impactor or cascade sampler. In this chapter, basic principles, applications, design and operation considerations of isokinetic sampling and cascade impaction are introduced. 

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