Fume hood chemistry

Chemical fume hood: safety equipment that removes toxic vapors and protects researchers in laboratories.

About this subject

Chemical fume hoods are essential safety devices in laboratories that handle volatile, toxic, or odorous substances. Their operating principle is based on local exhaust ventilation, which maintains a constant airflow from the front opening into the hood, preventing contaminants from spreading into the room. Typical face velocity ranges from 0.3 to 0.5 m/s, as per standards such as ANSI/ASHRAE 110.

There are two main types: ducted fume hoods (exhausted to the outside) and ductless fume hoods. Ducted hoods are more common in organic and inorganic chemistry labs as they remove gases without recirculation. Ductless hoods use activated carbon or HEPA filters to purify air before returning it to the room, suitable for small quantities of volatile solvents.

Regular maintenance is critical: containment tests and continuous monitoring ensure effectiveness. Brazilian standard NBR 13572 and international ANSI Z9.5 specify design and performance requirements. Additionally, proper placement of equipment inside the hood (avoiding airflow blockages) and sash height directly impact safety. Historically, fume hoods date back to the early 20th century, with the development of exhaust cabinets for handling radioactive and toxic substances.

Frequently Asked Questions

Why is a fume hood important in chemistry laboratories?

It protects the researcher from inhaling toxic vapors, flammable gases, or hazardous particles, ensuring a safe work environment and compliance with safety standards.

What is the difference between a fume hood and a biosafety cabinet?

A fume hood protects only the user and the environment, not the sample. A biosafety cabinet protects the user, the sample, and the environment using HEPA filters and laminar flow.

How often should a fume hood be tested?

Containment testing is recommended annually or whenever the exhaust system changes. Face velocity should be checked periodically according to standards.