Comparison of Generation Techniques

Another difficulty experienced when using the sparging method is the possibility of unintended aerosol production and transport with the vapor. Expedient measures can be implemented to remove aerosols from the product stream, including aerosol filtration and maintaining the sparger at subambient temperature however, this phenomenon reduces the operator s ability to establish predictable concentration with the generator s operating conditions. 

The delta tube behaves similarly to the diffusion generator except that it has a more positively controlled carrier fiow that can overcome the generator s internal system pressure. A diffusion system, which the vapor from the substance passively diffuses depending on flow dynamics of the system, can be quite unpredictable due 

The SSVG method is ideally suited for direct generation of low flux streams (i.e., low concentration and low flow rate) without the need for further dilution. Another potential advantage of this method, which has not been explored yet, is the ability to reduce head pressure over a high-volatility vapor or gas that might normally 

Potential problems associated with the S SVG method include decomposition of the adsorbate as a result of intimate contact with adsorbent reactive sites. This effect has been observed for adsorbed HD and VX recently, and seems to be exacerbated by the presence of water vapor. Efforts to minimize this effect include use of low-ash adsorbents, operating at as low a temperature as possible, and avoiding the presence of water. The latter includes sample preparation methods to reduce water contamination and use of ultra-dry carrier streams since water vapor in the carrier 

Syringe pump generation has a low-concentration generation limit, injecting as little as 0.1 mg/min of GB into an airstream at a flow rate of 1000 to 15001/min to reach a final concentration near 0.1 mg/m. It is not suitable for low-concentration generation. 

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