Views: 0 Author: Site Editor Publish Time: 2021-11-10 Origin: Site
Ductless fume hoods are stand alone, bench top enclosures that use self-contained carbon and/or HEPA filters to remove fumes, vapors and particulates from air drawn into the device and then recirculated into the lab. The intent is to offer a replacement for a conventional chemical fume hood attached directly to the building exhaust system. For proper and effective use filters must be discarded and replaced when they near a chemical saturation point. The ductless fume hoods were evaluated for face velocity, air flow patterns, spill control, noise levels, chemical breakthrough alarm response, and the solvent retntivity of the carbon filters.
Ductless fume hoods are marketed as cost saving alternatives to standard laboratory chemical fume hoods. It features in quicker installation time and lower installation costs by not having to install duct work and fans, energy saving due to not exhausting conditioned air to the outside, and also with portability.
2.1 Ductless fume hoods do not consume any air since they filter and recycle the air back into the room in which they are set-up.
2.2 Ductless filtering fume enclosures do not require rooftop exhaust ducts or make-up air systems as they recycle and filter the laboratory air at an average rate of 6,000 cubic feet per hour. Ductless filtering fume enclosures are immediately available for use without lengthy or costly installation requirements.
2.3 Ductless filtering fume enclosures do not exhaust chemical pollutants in the atmosphere. They are mobile and can evolve along with their changing laboratory environment. They can be temporarily stored and dispatched where needed by a safety officer for a scheduled class or project and also at a moment’s notice to protect users in cases when an impromptu need suddenly arises.
3.1 Is the chemical or groups of chemicals, which I am using retained by the filter under the conditions set by the AFNOR NFX 15-211 standard?
3.2 If yes, what will be the lifetime of the filter in relation to the frequency of my handlings and their evaporation rate?
3.3 Will I have access to a reliable automatic filter saturation detector?
3.4 If not, what will be the detection methods provided?
3.5 Will the manufacturer keep me safe by offering services or programs that will monitor my application changes and preserve the intended usage of my ductless filtering fume enclosure?
Far more recent, ductless filtering fume enclosures have only been around for about 40 years. Created in 1968, their technology is directly inspired from the activated carbon technology found in the modern gas mask. Today, ductless filtering fume enclosures are using the properties of activated carbon combined with catalysts and certain neutralizers in order to filter toxic molecules, therefore eliminating their dependency upon HVAC and the need to be connected to external ductwork.
In the event that satisfactory responses cannot be provided to insure the safe usage of a ductless filtering fume enclosure, a decision should certainly be made in favour of selecting a ducted fume hood.