Methodologies for Determining Capture Efficiencies in Surface Treatment Tanks

Abstract

Methodologies are proposed for determining capture efficiencies in the ventilation systems of surface treatment tanks, using test-scale equipment. The equipment, which incorporates a lateral and push-pull ventilation system, can measure and control the variables of interest because it incorporates a tracer gas generator (sulfur hexafluoride, the concentration of which is measured by infrared spectrometer). The experimental methodologies described determine total efficiency (when the tracer is emitted uniformly from the whole surface of the tank) and the so-called transversal linear efficiency (when the tracer is emitted linearly through a perforated tube situated over the tank, parallel to the exhaust hood face). The analytical and graphical relationships that can be are established between the two efficiencies make it possible to detect where the emissions not captured by the ventilation system are produced (i.e., losses to the outside). At the same time, such losses can be quantified. Several experiments, results of which are analyzed by the methods described, are included.

Aerodynamics and Performance Verifications of Test Methods for Laboratory Fume Cupboards

“…The quantitative containment tests can provide more valuable information of ventilation system performance than that provided by the traditional face velocity measurement. A similar system for surface tanks was suggested by Marzal et al (2002Marzal et al ( , 2003aMarzal et al ( , 2003b. Usually, a tracer gas such as sulfur hexafluoride (SF 6 ) is delivered into the cupboard at a known rate and measurements of concentration are collected around the cupboard to determine gas escape.…”