Ductless Fume Hood
Ductless laboratory fume hoods are ventilated enclosures that have their own fan, which draws air out and through filters and ultimately recirculates it into the laboratory. The filters are designed to trap vapours generated in the chemical hood and exhaust clean air back into the laboratory.
Ductless laboratory fume hoods should be used only where the hazard is very low, and where the access to the hood and the chemicals used in it are carefully controlled.
- ASHRAE 110
- 4 Feet
- 5 Feet
- 6 Feet
- Not applicable
A ductless hood equipped with a filtration device designed to control non-toxic chemicals, nuisance odors, particulates
A ductless hood capable of meeting all DH I requirements, and equipped with a filtration device designed to filter manufacturer approved toxic contaminants up to filter break through only. A DH II ductless hood is not designed to provide secondary containment beyond primary filter break through
A ductless hood capable of meeting all DH II requirements, and equipped with a filtration device designed to fi lter manufacturer approved toxic contaminants beyond primary filter break through by providing secondary back-up protection. Once the primary filter break through point has been detected a DH III ductless hood should be designed to provide a period of time to continue and end an ongoing experiment with its secondary back-up filter system. The secondary filter must be of the same type of media and efficacy, as the primary filter