Fumes are vapors or dusts that are given off from a substance as a result of a chemical transformation. They may be irritating, hazardous or toxic.

In laboratories, fume hoods are installed to provide safe working conditions for employees who work with chemical substances. They must be exhausted separately from the room exhaust system.

What is a Fume Hood?

Fume hoods are a critical component of any laboratory, especially those that use open chemicals. They filter and contain hazardous fumes and vapors, keeping lab professionals safe from potentially deadly toxins.

Chemical fume hoods are required when a laboratory uses any open chemical with a Safety Data Sheet (SDS) statement of “Do not breathe dust, fumes or vapors”. Talk to your lab specialist about how to best handle specific hazards in a laboratory and what fume hood will be most effective for your application.

All hoods on campus should be labeled with current calibration stickers and a marker indicating the highest sash height to use when working with hazardous materials. If these labels are missing or the sash is not closed properly, contact EH&S for an evaluation of your hood.

Fume Hood Design

Fume hoods are designed to handle a variety of chemicals. Some fume hoods are constructed of special acid-resistant materials and incorporate water wash down systems to keep the vapors from condensing and causing explosions.

These types of fumedisposablevapes.com are often used in metallurgical labs and for rocket fuel production. They can also be used to digest or break down metal samples, identifying their chemical composition by breaking them down into component parts.

The sash on a fume hood is designed to open and close, allowing air flow across the hood opening to adjust to the point where contaminants can be captured. The sash is marked with the optimum position, and should be held in that position while working and closed when not in use.

Fume Hood Ventilation

The ventilation of a fume hood is critical to the safety and efficiency of its operations. It relies on the flow of air through a fan connected to ductwork attached to the hood.

It also uses baffles to direct airflow in a specific direction and exhaust the contaminants that are trapped inside the hood. The baffles can be adjusted depending on the vapor density of the chemicals used in the laboratory.

Objects and equipment placed too close to the front of the fume hood can interfere with airflow and increase the risk of contamination. All materials should be placed at least 6 inches from the face of the hood.

Objects that block the return ducts and baffle areas can interfere with airflow, allowing contaminants to be pulled from the back of the hood and escaping into the work area. Large equipment should be positioned in the back and smaller pieces placed in front for better airflow.

Fume Hood Safety

When working in a fume hood, there are several safety precautions to follow. These include lowering the sash, keeping all chemicals behind a safety zone line inside the hood, and not making rapid movements near the front of the hood.

If there is a loss of airflow or the face air velocity indicator sounds alarming, immediately discontinue operations and close the sash fully. This will prevent a fire from starting in the fume hood.

Keep combustible material such as paper towels, work surface diapers, or cardboard out of the hood. These can draw vapors into the hood’s ventilation system and increase the risk of fire or explosion.

Mark a six inch safety zone on the front of the bench surface and keep all chemicals and equipment behind this line during experiments. This will prevent vapors from escaping when disturbances like air currents from people walking past the hood interfere with the proper airflow.