Use, function and limitations

A chemical fume hood is the main laboratory equipment that protects workers when handling hazardous chemicals. They are engineering controls designed to protect workers from chemical hazards. Fume hoods are connected to an independent exhaust system that discharges the air from inside the fume hood to the outside of the building and are designed to be workspaces and not to be used for storage. Some chemical or a small satellite accumulation area may be kept in a fume hood as long as it does not disrupt airflow or inhibit workspace. 

Fume hoods should operate between 80 and 120 feet per minute, depending on the laboratory chemical safety level. The VCU Minimum Lab Design Specifications outline the required face velocity for standard, high and specialty-use labs. All fume hoods must have a calibrated audible visible flow alarm to alert users if airflow is at an unsafe level. Fume hoods should be tested and certified annually. If the flow alarm on your fume hood indicates an unsafe condition or if you suspect the fume hood is not working properly, immediately stop working, close all chemical containers, shut the sash and contact EHS-SRM Laboratory Safety. You may also submit a work ticket to VCU Facilities Management via the Facilities Self Service for any issues or repairs needed to ducted fume hoods.

Chemical Fume hood face velocity is checked for use and function during annual laboratory safety assessments by the VCU Lab Safety team. Fume hood certification is done through certified third party vendors, not the VCU Lab Safety team.

The following general guidelines must be followed for safe handling of hazardous chemicals (see the Fume Hood information document or the VCU Chemical Hygiene Plan for more information): 

• Operate the hood at the proper sash height, which will vary based on the fume hood. Most fume hoods will have a mark for the appropriate sash height.
• Minimize the release of contaminants into the work area by reducing pedestrian traffic in front of hoods, particularly during hazardous experiments.
• Do not block airfoil. The airfoil provides airflow across the floor of the hood, especially when the sash is closed. (e.g., absorbent paper).
• Work as far inside the hood as possible, at least six inches from the front edge with the sash face between you and the task at hand. For fume hoods with sliding panels and liftable sash, only use the sliding panels for setup and breakdown and do not have the panels open while working with hazardous material or while an experiment is running.
• Do not use the hood as a storage cabinet for the chemicals or equipment. Materials stored in fume hoods should be kept to a minimum and stored in a manner that will not interfere with airflow. Evaporating chemicals for disposal purposes is not allowed. 
• Wear protective equipment (PPE). Fume hoods do not prevent accidents or chemical splashes. PPE (e.g., safety glasses, gloves and aprons) appropriate to the conditions must always be worn.
• If the flow alarm is indicating an unsafe condition, do not ignore it or attempt to bypass the alarm. Immediately stop work, shut the sash and contact EHS-SRM Lab Safety to report the issue. 
• Close the sash when finished with work or when leaving experiments or chemicals unattended. This procedure will contain fires and explosions within a hood and can reduce the amount of energy required to power the hood.