Periodic Flow Purging System for Harvesting Fibers from Screens

Bon Ki Ku,Leonid A Turkevich,Gregory Deye

doi:10.4209/aaqr.210033

Abstract

ABSTRACT Fiber length is believed to be an important factor in determining various toxicological responses to asbestos and other bio-persistent fibers. Length classification of fibers thus is crucial for toxicological assessment. Nylon mesh screens have been shown to be effective in separating fibers by length. In this note, we report development of a purging flow system for harvesting fibers from a nylon net screen, with the aim of separating airborne fibers by length. We evaluated the performance of this purging flow system by examining the lengths of glass fibers collected on a screen. Fibers aerosolized by vortex shaking were provided to 10 µm and 20 µm mesh screens, and the fibers collected on each screen were purged periodically with a backflow. The length of the purged fibers was measured and compared to that of fibers washed from the screen. The mean length of fibers on the screen is larger than that of the fibers in the original test aerosol. The mean length of the backflow purged fibers is smaller than that of the fibers from the washed screen. The results indicate that the purging flow system with screens can harvest the longer fibers from the original aerosol.

Highlights

Received: February 12, 2021 Revised: March 23, 2021 Accepted: March 25, 2021Publisher: Taiwan Association for Aerosol Research ISSN: 1680-8584 print ISSN: 2071-1409 onlineCopyright: U.S Government work
Classification of airborne fibers by length is essential for sample preparation in any experiment that seeks to understand the effect of fiber length on toxicity (Stanton and Layard, 1978; Stanton et al, 1981; Davis et al, 1986; Donaldson et al, 1989; Goodglick and Kane 1990; Blake et al, 1998; Miller et al, 1999; Baron, 2001; Dodson et al, 2003; Zeidler-Erdely et al, 2006; Donaldson et al, 2010; NIOSH, 2011; Schinwald et al, 2012; Padmore et al, 2017)
Previous studies showed that fibers penetrating through screens were predominantly short fibers and that, depending on screen pore sizes and configurations, long fibers could be completely excluded from the transmitted aerosol (Spurny et al, 1969; Myojo, 1999; Ku et al, 2014)

Summary

INTRODUCTION

Publisher: Taiwan Association for Aerosol Research ISSN: 1680-8584 print ISSN: 2071-1409 online. Ku et al (2014) demonstrated that nylon mesh screens can be effective in obtaining short fibers which penetrate through the screens. To minimize the loading effect on screen collection efficiency, and to harvest the long fibers collected on the screen, a method for recovering the collected fibers from the screen is Aerosol and Air Quality Research | https://aaqr.org. Ku et al (2017a) recently reported that fibers could be harvested from the screen by back-flow purging. This note reports on the development and evaluation of a periodic flow purging system of a screen for use in length separation of airborne fibers. The periodic purging reduces fiber accumulation on the screen, thereby minimizing the depth filtration change in screen performance. We have harvested long fibers collected on the screen and compared the length distributions of the harvested fibers to those of fibers obtained from washing the screen

EXPERIMENTAL

Fiber Length Analysis

Screen Washing Procedure

RESULTS AND DISCUSSION

CONCLUSIONS