Last Revised: November 17, 2022
Revision 11/2022
Use of Fume Hoods
Proper use of laboratory fume hoods can be found in the Controlling the Risks of Chemical Hazards in Penn's Chemical Hygiene Plan.
More information about laboratory fume hoods including repair procedures can be found on the EHRS website at: Lab Safety > Fume Hoods.
Approved fume hood vendors
EHRS should always be consulted on the fume hood selection and placement for new or renovated labs.
Laboratory fume hoods manufactured by Kewaunee Scientific Corporation, Mott Manufacturing, Baker, Labconco or Lab Crafters are preferred. Hoods from other manufacturers will be considered but must be pre-approved by EHRS. The manufacturer label must be affixed on the outside of the hood.
If salvaged hoods will be reused, the design team is responsible for inspecting and validating the equipment. Any modifications must meet the manufacturer's original specifications.
Ductless/filtering fume hoods must be approved by EHRS before installation.
Installation
Design professionals should consult NFPA 45 section 7.9 regarding the placement of fume hoods with the laboratory.
A person walking past the hood can create sufficient turbulence to disrupt a face velocity of 0.5 m/sec (100 ft/min). In addition, open windows or air impingement from an air diffuser can completely negate or dramatically reduce the face velocity and can also affect negative differential air pressure. Considerations for minimizing air turbulence include:
- Not locating hood adjacent to a single means of access to an exit or high traffic area
- Not placing a hood in a main pathway of travel
- Not locating workstations not directly related to the chemical fume hood activity in front of the fume hood opening
Hoods located immediately next to each other or immediately across from each other can create adverse effects on each other.
Hood Commissioning
Hoods must be tested by both EHRS and a vendor before they can be used by the lab occupants. The project manager must inform EHRS when a new hood has been installed. EHRS will then conduct a preliminary test of airflow and alarm function and will let the project manager know if the hood meets specifications. If balancing is needed, this must be done before EHRS tests the hood. Upon receiving EHRS approval, the project manager must contract a vendor to do ASHRAE 110 testing of the hood and provide them with the following Penn specific standards:
With the sash height at 18 inches, each hood shall maintain an average face velocity of 80-120 fpm with no face velocity measurement more than plus or minus 20% of average [per ANSI/AIHA Z9.5]. Low-flow alarms shall be set below 80 fpm.
Hoods must meet ASHRAE 110-most current Tracer gas test protocol with a rating of 4 AI 0.1 and the Flow Visualization and Velocity Procedure tests. A Professional Engineer shall seal test reports. Reports shall be provided to EHRS.
Vendors who have performed ASHRAE 110 testing at Penn include TSS, Steris, and 3Flow; however, other vendors may be selected.
*On/off switches for blowers are not permitted.
Directional supply air diffusers shall not discharge air toward the hood nor shall they be installed within 10 feet from the hood.
Casework under hood
A Factory Mutual approved, UL listed flammable liquids storage cabinet in compliance with NFPA 30 and OSHA regulations shall be installed under the fume hood. See Flammable Liquids Storage Cabinets Specification for guidance on storage capacity.
If vacuum pump cabinets are required under the fume hood, the design team should consider the following factors:
- Power requirements
- Removal of heat
- Noise/Vibration
- Ventilation of by active exhaust or inclusion a port for the exhaust hose to vent directly into lab exhaust duct or fume hood interior.
Labeling
The hood shall be labeled with the exhaust fan number and location. A manufacturer label must be affixed to the outside of the hood.
Hood Interior
Hood interior must have a flame-spread index of 25 or less.
Labeling of Utility Valve Handles
Color-coding alone is not sufficient for labeling of utility valve handles on and inside fume hoods. Colors for different utilities must not be duplicated. For more information, see Water Saver Service Fixture Indexing.
Other Local Exhaust Ventilation
EHRS must approve the installation of a point exhaust for managing hazardous chemical vapor or gases, as point exhausts do not provide the same level of protection as hoods and may not be appropriate for all applications. Point exhausts for processes and equipment may include canopy hoods, exhaust "drops", snorkels, ventilated bench-top enclosures, and other similar devices. Common equipment types that require local exhaust points are glove boxes, vacuum pumps, drying ovens, chromatography equipment, or other processes involving hazardous materials when they cannot be done inside a chemical fume hood.
Whenever new exhaust points are added as part of a renovation project a means of verifying the exhaust function must be included. If there is a fume hood in the room that is served by the same fan, the point exhaust must be labeled with the fume hood number. EHRS will track the point exhaust connection in the equipment inventory record for the fume hood. If there is not a fume hood in the same room as the exhaust point, the point exhaust must be equipped with a device such as a Magnahelic gauge or sail switch alarm.