AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Room Scale Deposition of Chem/Bio Decontaminants Dispersed through Commercially Available Induction Spray Charging Nozzles
Joshua Hubbard, Rita Betty, Daniel Lucero, Danielle Rivera, ANDRES SANCHEZ, Brandon Servantes, Sandia National Laboratories
Abstract Number: 55 Working Group: Homeland Security
Abstract Inertial, electrostatic, and gravitational droplet deposition velocities were measured in a 2.5 x 2.5 x 2.5 meter spray chamber. Commercially available chem/bio decontaminant (DF-200) was dispersed through two electrostatic induction nozzles: a two fluid nozzle from Electrostatic Spray Systems (ESS) used for agricultural purposes, and a rotary atomizer from Illinois Tool Works (ITW) designed for automotive paint applications. Spray droplet size distributions were measured with a Malvern Spraytec light scattering instrument. DF-200 was then tagged with sodium fluorescein and sprayed with and without droplet charging to assess the effects of electrostatics on chamber deposition. Stainless steel coupons were placed in multiple locations in different orientations to differentiate between the following deposition mechanisms: inertial, gravitational, and electrostatic. Chamber aerosol concentrations were measured with fiberglass filters and SKC biosamplers. Coupons were recovered from the chamber and serial dilutions were performed to quantify the aerosol mass deposited. The average deposition flux (g/m$^2s) was normalized by the average air concentration (g/m$^3) to obtain the average deposition velocity (m/s) for each surface. Floor deposition was in good agreement with gravitational settling velocities. Vertical surfaces outside the spray plume showed significantly enhanced deposition (one to two orders of magnitude higher) when droplets were charged.