When you are considering buying a ductless fume hood vs ducted fume hood what major things should you consider? Installation costs play a large role, as well as unit functionality, safety, and operational costs.
What's The Difference?
A ducted fume hood is a ventilated enclosure where an exhaust fan pulls air and airborne contaminants through connected ductwork and exhausts them to the atmosphere.
Ductless fume hoods filter out chemical fumes using activated carbon filters and recycle the air directly back to the working environment.
The Numbers
Ducted fume hoods take conditioned inside air and exhaust it outside, requiring new air to be conditioned to replace it. Ductless hoods filter and recirculate air, requiring no make-up air. This has a substantial effect on yearly operating costs.
Ducted Fume Hood
Ducted systems give you the ability to work with a broad range of chemicals. Because the air is pushed outside, there is little risk of hazardous particulate recirculation. However, being attached to the HVAC system requires working around maintenance schedules.
Ductless Fume Hood
Ductless systems can come in at a lower installation price and lower annual operational cost. However, depending on the chemicals being used you may be limited by the filter. A HEPA filter that captures up to 99.97% of particles may not be enough if the chemicals are particularly harmful.
Common Ductless Fume Hood Filters
ASHRAE Filter: up to 95% efficient on particles down to 0.5 microns
HEPA Filter: up to 99.97% efficient on particles down to 0.3 microns
ULPA Filter: up to 99.9995% efficient on particles down to 0.12 microns
Activated Carbon Filters: Efficiency varies