This document discusses ductless hoods as an alternative to traditional ducted fume hoods for laboratory ventilation. It provides examples of when ductless hoods may be preferable, such as when building limitations prevent ducting or when chemical usage is minimal. The key considerations for using ductless hoods include conducting a hazard assessment, selecting the appropriate filter type, and implementing controls like service contracts, pressure gauges, signage and training. Case studies demonstrate how ductless hoods have been used successfully in situations involving limited chemical usage.

1. Ductless Hoods
Erik Talley / Matthew Brinton
Environmental Health and Safety
Emerging Trends in Laboratory Ventilation
ACS Fall 2009 National Meeting
Washington DC August 15- 20, 2009

2. What is a “Ductless Hood”?
Enclosure + Fan + Filter =
Ductless Hood
Environmental Health and Safety
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3. No!!!!
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4. Design Limitations
 Recirculation of exhaust air is
potentially dangerous.
– Limited Filter Capacity (saturation,
breakthrough, stripping)
 Filter Changes (handling of used
filters, including hazardous waste
disposal as a hidden cost)
 Poor design
 Chemical hoods are used for more
than just chemical containment (e.g.
fire, explosions)
 Not typically maintained by
Facilities
 User Knowledge/Misuse
Environmental Health and Safety
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5. Why consider ductless?
(building limitations)
Baker Pavilion Existing External Ducts Centre Georges Pompidou
Environmental Health and Safety
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6. Why consider ductless?
(continued)
 Increased safety for benchtop work or
equipment.
 Standard chemical hood design
interferes with needs (e.g. dust
weighing)
 Insufficient need to justify
infrastructure/operational costs of
ducted hood (installation cost, space
needs) .
Environmental Health and Safety
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ehs@med.cornell.edu
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7. Why consider ductless?
(continued)
 Energy efficiency (A
single ducted chemical
hood running 24/7/365
uses as much energy
as a single-family
home.)
 Pollution capture
Environmental Health and Safety
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8. Hazard Assessment
 An Industrial Hygienist
must conduct a
comprehensive Hazard
Assessment including:
–Type of Hazards
–Frequency of Use: Dose
–Duration of Use: Dose
–Hazard Generation
Characteristics
–Effluent Characteristics
Environmental Health and Safety
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9. Limited Filter Applications
 HEPA
– Powder weighing,
nanoparticulates, etc.
 Adsorbent Cartridges
– Nuisance odors
– Low toxicity chemicals
– Applications where chemical
usage is:
• limited (volume and time)
• consistent
• controllable
 Dual Filters
– Animal Surgeries
Environmental Health and Safety
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10. Controls
 Service Contract
 Connect to house
exhaust if possible
(canopy, thimble)
 Minihelic Pressure
Gauge (HEPA), Flow
Monitor, Vapor Sensor
 Signage
 Training
 Inspections
Environmental Health and Safety
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11. Case Study - Gross Anatomy
 Plastination
– New Process
– Limited Use
– Single chemical hazard (organotin
compound)
– Very Limited Space
 Hood Selection
– Activated carbon
 Controls
– Air exhausted to outside after
being filtered
– Limited Access
– Training
– Inspection
Environmental Health and Safety
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12. Case Study - Clinic
 Urology
– Endoscope disinfection
machine
– Located in interior of building
with no exhaust options
– Gluteraldehyde (5%) Solution
 Hood Selection
– Carbon filter hood designed
specifically for the endoscope
machine
 Controls
– Service Contract
– Labeling
– Training
Environmental Health and Safety
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13. Case Study – Laboratory
 Epigenomics Core
Laboratory
– Chemical use limited to sample
preparation
• ~125 ml total chemical usage/month
– Hood use approximately 30-60
minutes a week
 Hood Selection
– Dual Filter
 Controls
– Limited Access
– Labeling
– Service Contract
– Training
Environmental Health and Safety
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ehs@med.cornell.edu
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14. Resources
Environmental Health and Safety
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