The role of exhaust ventilation systems in reducing occupational exposure to organic solvents in a paint manufacturing factory

Abstract

This paper presents the successful design and implementation of several exhaust ventilation systems in a paint manufacturing factory. The ventilation systems were designed based on American Conference of Governmental Industrial Hygienists recommendations. The duct works, fans, and other parts were made and mounted by local manufacturers. The concentrations of toluene and xylene as the common solvents used in paint mixing factories were measured to evaluate the role of ventilation systems in controlling the organic solvents. Occupational exposure to toluene and xylene as the major pollutants was assessed with and without applying ventilation systems. For this purpose, samples were taken from breathing zone of exposed workers using personal samples. The samples were analyzed using Occupational Safety and Health Administration analytical method No.12. The samples were quantified using gas chromatography. The results showed that the ventilation systems successfully controlled toluene and xylene vapors in workplace, air well below the recommended threshold limit value of Iran (44.49 and 97.73 ppm, respectively). It was also discovered that benzene concentration in workplace air was higher than its allowable concentrations. This could be from solvents impurities that require more investigations.

Keywords: Exhaust ventilation systems; occupational exposure; paint manufacturing; ventilation standard.

Figure 1

Layout of equipment in the production hall

Figure 2

Local exhaust ventilation of wall mixers (slotted lateral hoods)

Figure 3

Local exhaust ventilation of Millers (eight canopy hoods near the pollution sources)

Figure 4

Local exhaust ventilation of powder mixers (includes four semi-circular laterals slotted hoods)

Figure 5

General exhaust ventilation systems (each system includes four lateral slotted hoods that exhaust air from floor and upper zones of the hall

Figure 6

Exhaust ventilation of enclosed container (a single branch system attached to the container cap that can be assembled on each container in turn)

Figure 7

Chromatograph of one of the samples (part A of the charcoal tube)

Figure 8

Chromatograph of one of the samples (part B of the charcoal tube)

Figure 9

Comparison of designed air flow with measured air flow

Figure 10

The comparison of concentrations with TLVs (all values in ppm) early benzene