Effects of Sash Movement and Walk-bys on Aerodynamics and Contaminant Leakage of Laboratory Fume Cupboards

Tseng, Li-Ching; Huang, Rong Fung; Chen, Chih-Chieh; Chang, Cheng-Ping

doi:10.2486/indhealth.45.199

Cited by 12 publications

(11 citation statements)

References 12 publications

(11 reference statements)

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“…The comparison of the particulate and gaseous behaviours again demonstrates that the operation of a MSC, or any other comparable containment system, is very sensitive to the ambient ventilation conditions (Johnson & Fletcher 1996;Tseng et al, 2007a and2007b;Nicholson et al, 1999). The influence of the physicochemical properties, the intensity and the lay-out of the source, as well as the presence of an electric field, are also equally important parameters to explore to obtain a solid and complete database.…”

Section: Discussionmentioning

confidence: 92%

“…The type test described in both standards is based on the use of tracer gas or micrometric aerosol. In addition, many authors have demonstrated the influence of various parameters on the performance levels of these systems, including the air velocity in the aperture (face velocity), the presence of an operator, variations in sash openings, operator movement in front of the enclosure (Johnson & Fletcher 1996;Tseng et al, 2007a and2007b;Nicholson et al, 1999;Rake, 1978). Most of these studies are based on using a tracer gas and demonstrated that the containment efficiency was sensitive to experimental condition variation.…”

Section: Introductionmentioning

confidence: 99%

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Assessing the Containment Efficiency of a Microbiological Safety Cabinet During the Simultaneous Generation of a Nanoaerosol and a Tracer Gas

2012

The Annals of Occupational Hygiene

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The intention of this article is to compare the containment performance of a Type II microbiological safety cabinet (MSC) confronted with the simultaneous generation of a saline nanoparticle aerosol and a tracer gas (SF(6)). The back dissemination coefficient, defined as the ratio of the pollutant concentration measured outside the enclosure to the pollutant flow rate emitted inside the enclosure, is calculated in order to quantify the level of protection of each airborne contaminant tested for three enclosure operating configurations: an initial configuration (without perturbations), a configuration exposing a dummy in front of the enclosure (simulation of an operator), and a configuration employing the movement of a plate in front of the enclosure (simulation of human movement). Based on the results of this study, we observed that nanoparticulate and gaseous behaviours are strongly correlated, thus showing the predominance of air-driven transport over particle-specific behaviour. The average level of protection afforded by the MSC was found systematically slightly higher for the nanoaerosol than for the gas in the studied configurations (emission properties of the source, operating conditions, and measurement protocols). This improved protection efficiency, however, cannot be considered as a warrant of protection for operators since operating condition and ventilation parameters are still more influential on the containment than the pollutant nature (i.e. nanoaerosol or gas).

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Assessing the Containment Efficiency of a Microbiological Safety Cabinet During the Simultaneous Generation of a Nanoaerosol and a Tracer Gas

2012

The Annals of Occupational Hygiene

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“…A ventilated enclosure is used to carry out a tracer gas transport experiment. This enclosure is a parallelepiped box of volume 0.128 m 3 where air is injected permanently at a flow rate of 40 L • min −1 through a 4 cm diameter circular inlet and evacuated through an outlet of the same dimension. This results in an air jet with an inlet-based Reynolds number of 1500 (the experiment is described in detail in [6]).…”

Section: Methodsmentioning

confidence: 99%

“…Their role is to reduce the risk of inhalation of hazardous vapours through their confinement. Despite this, the confinement of these hazardous fumes has been shown to be broken by disruptive air draughts [1,2,3,4,5]. Indeed, these confinement breaks generate leaks of toxic fumes outside these protection devices, exposing the operators to inhalation risks.…”

Section: Introductionmentioning

confidence: 99%

Assessment of discretization schemes applied to the transport of a passive scalar in a ventilated enclosure

Atallah

Belut²,

Lechêne³

et al. 2020

International Conference of Numerical Analysis and Applied Mathematics Icnaam 2019

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This paper is a comparative study of classical spatial discretization schemes applied to an experimental case. Numerical simulations are performed according to large cell Péclet numbers. This should show the limitations of some schemes such as the upwind-difference scheme (numerical diffusion) or the central-difference scheme (overshoot and undershoot) for large cell Péclet number. However, in the case of the transport of tracer gas concentration in a ventilated enclosure, we show here that these kinds of schemes are a priori sufficient.

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“…The tracer was released through a 50-mm diameter glass ball filter which was mounted in the right hand of the mannequin (assumptive contaminant source point), and a mass flow controller (Model MC-3000E; LINTEC Ltd.) was used to reduce fluctuations in the tracer gas flow. The flow rate of the tracer gas was set at 4.5 l/min in accordance with a former study 3) . The distance between the center of the blockage panel and the ball filter was about 3 cm.…”

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confidence: 99%

Tracer Gas Evaluations of Push-Pull Ventilation System Performance

Ojima

2009

Ind Health

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Since the revisions to the Industrial Safety and Health Law of Japan (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005), push-pull ventilation systems have been introduced as effective means of protection for industrial workers dealing with hazardous materials. Compared with an ordinary local exhaust hood, a pushpull ventilation system can be used for contaminant control over a large working area, and is suitable for painting, welding, foundry and soldering operations. Although a push-pull ventilation system has several advantages over a local exhaust hood, some laborious adjustments, such as finding the correct balance between supply flow rate and exhaust flow rate, are required prior to use. Generally, the pertinence of the adjustments is uncertain because it is practically difficult to evaluate the performance of a push-pull ventilation system quantitatively by a conventional velocity measurement test. The uniform flow velocity of a push-pull ventilation system is not a direct measure of its ability to provide industrial worker protection. In this study, an assessment of capture efficiency (usually defined as the ratio of air contaminant quantity captured by a ventilation system per unit time to the total contaminant quantity produced by the process per unit time) indicating the performance of a push-pull ventilation system was carried out by means of a tracer gas method. Specifically, this paper describes the effects of a uniform flow velocity and the presence of a blockage in the ventilation zone on the capture efficiency of the push-pull ventilation system. All experiments were conducted by using an actual open type push-pull ventilation system in a laboratory.Figures 1-1 and 1-2 show the set-up of the experimental apparatus. As shown in these figures, a spray painting operation was simulated in this experiment.The push-pull ventilation system was a KOKEN Pushpull Laminar System Model MS-01. The ventilation zone of the system was 0.7 × 0.7 × 1.5 m in size. The supply flow rate of the push unit and the exhaust flow rate of the pull unit were regulated by means of a transformer and an inverter, respectively. Prior to the experiments, the MS-01 was adjusted so as to fulfill the requirements of a push-pull ventilation system prescribed by Japanese Industrial Safety and Health Law. The experiments were carried out at three different uniform flow velocities of 0.37 m/s, 0.40 m/s and 0.44 m/s. The ratio of the pull flow rate to the push flow rate was 1.20 at a uniform flow velocity of 0.37 m/s, 1.75 at 0.40 m/s and 1.49 at 0.44 m/s, respectively.At the middle of the push unit and the pull unit ( Fig. 1-1), blockage panels (980, 1,960, 2,940 and 3,920 cm 2 , corresponding to 20, 40, 60 and 80% of the cross-sectional area of the ventilation zone, respectively) which simulated painted products were placed at the centerline of the Abstract: A push-pull ventilation system is effective for hazardous material exhaustion. Although a push-pull ventilation system has advantages over a local exhaust hood, some laborious...

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Effects of Sash Movement and Walk-bys on Aerodynamics and Contaminant Leakage of Laboratory Fume Cupboards

Cited by 12 publications

References 12 publications

Assessing the Containment Efficiency of a Microbiological Safety Cabinet During the Simultaneous Generation of a Nanoaerosol and a Tracer Gas

Assessing the Containment Efficiency of a Microbiological Safety Cabinet During the Simultaneous Generation of a Nanoaerosol and a Tracer Gas

Assessment of discretization schemes applied to the transport of a passive scalar in a ventilated enclosure

Tracer Gas Evaluations of Push-Pull Ventilation System Performance

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