Fume hoods are designed to provide personnel protection from toxic or volatile chemicals by continuously shifting airflow away from the user and to the work area. Fume hoods are often the most used piece of equipment in research laboratories and frequently shared by lab personnel.
In ordinary times, keeping the work area and operator safe is absolutely essential, but during these extraordinary times, it’s fundamental. When it comes to installing and using a fume hood in your laboratory, here are some principle tips and reminders to consider.
Location, Location, Location
Since a smooth entry is vital, placement of the hood in the laboratory requires careful consideration. Layout of the laboratory and location of the chemical fume hood are important for optimal performance and minimal interference.
Locate fume hoods away from doorways and exits. The National Fire Protection Association recommends that they be ten feet from any door or exit. The explanation is simple, in that the exit would be blocked should a fire or chemical release occur. Additionally, the constant traffic can potentially disturb the needed smooth flow into the hood. Other factors that can disturb airflow include air supply diffusers, doors and windows, as these could affect the ability of the hood to capture and exhaust contaminants in the way it’s designed to.
It’s important to avoid placing the chemical fume hoods opposite from workstations, desks, microscope benches or other areas where personnel spend significant time. As noted above, the reason should be obvious—any incident in the hood could involve or injure anyone seated in front of the hood.
One final recommendation is to make sure cabinets and equipment do not block or interfere with the fume hood opening or the laboratory’s supply or exhaust vents. Having items stored on top of cabinets or in front of hoods or vents significantly disrupts the airflow.
It is up to the operator to know how to adjust flows for a particular need. Pay attention to proper flow and remember to adjust the baffles according to the work being done. Keep the following in mind when routinely checking the hood for adequate flow and velocity:
- Are there dead spots in the face velocity or inside the hood and are they located where capture is needed? We recommend face velocity be checked using a grid pattern with a minimum of six readings, and that readings not differ by more than ten percent. Alternately, air current or smoke tubes are useful in detecting dead or low-flow zones.
- Where is capture needed? Are you working with vapors that are lighter than air? Heavier? If they are heavier than air, then the dampers should be adjusted to capture at the bottom of the hood (i.e., open the bottom slot and close down the upper one). If storage or equipment is blocking the lower slot, this may hinder flow and thus proper capture. One quick fix is to install a shelf above the lower baffle so reagents and chemicals stored on the shelf do not block the lower slot. If the vapors are lighter than air, you may be okay with some storage in the hood. Use smoke tests to confirm this.
Designed to be installed almost anywhere in a facility where there is work to be done, Air Science® ductless fume hoods offer a range of benefits that permit research, manufacturing and processing functions to proceed with safety and efficiency.