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The Ultimate Guide to Fume Hoods: Definition, Types, Functions, and Safety Features

Apr 17, 2025

Table of Contents

What is a Fume Hood?

 

Fume Hood

 

A fume hood is a ventilated enclosure designed to limit exposure to hazardous or toxic fumes, vapors, and dust. It serves as a primary safety device in laboratories, industrial settings, and medical facilities where chemicals and biological substances are handled.

 

The typical fume hood resembles a cabinet with a movable front window called a sash. Inside, you'll find a work surface where procedures are performed, along with services like water, gas, and electricity. The defining feature is its exhaust system that captures and removes airborne contaminants.

 

Interestingly, the concept dates back to the 1920s when chemists used primitive "draft chambers." The modern fume hood evolved significantly during the post-WWII research boom when laboratory safety became a greater priority.

 

Types of Fume Hoods

Based on Installation

 

 

1.Bench-top Fume Hood

The most common type, sitting on a work surface approximately 36 inches above the floor. It requires a supporting base cabinet, work surface, and exhaust blower with appropriate ductwork.

2.Floor-mounted (Walk-in) Fume Hood

Installed from the floor up, resembling a small room. Ideal for working with oversized equipment like drums or robots. Standard models range from 6-24 feet wide and can be custom-made to specific dimensions.

Here to know more about walk in fume hood

3.Double-faced Fume Hood

Features entrances on both sides, allowing for 360-degree viewing. Available as bench-top, wall installation, or portable unit. Commonly used in classrooms for teaching demonstrations.

4.Canopy Fume Hood

Suspended or wall-mounted, designed to vent non-toxic vapors like heat, steam, and odors from large equipment. Unlike conventional hoods, it captures contaminants without requiring a physical barrier around the work surface.

 

Based On Air Flow System

 

 

1.Ducted Fume Hood

Draws air from the lab and exhausts it outside the building through ductwork. These are the most common in industrial and research settings.

2.Ductless (Recirculating) Fume Hood

Filters air through specialized media (typically activated carbon) and recirculates it back into the room. More energy-efficient but limited in application to known hazards compatible with the filter type.

Here to know more Ducted vs. Ductless Fume Hoods

 

Specialized Fume Hoods

 

 

1.Distillation Fume Hood

Features taller interior space to accommodate large distillation equipment used in chemical research, pharmaceutical testing, and petroleum industry applications.

2.Perchloric Acid Fume Hood

Includes a water wash-down system and built-in drain trough for handling perchloric acid. Regular cleaning prevents dangerous perchlorate salt buildup.

3.Radioisotope Fume Hood

Built with stainless steel surfaces and coved seamless welded corners to prevent contamination when handling radioactive materials. These are specially reinforced with watertight work surfaces.

4.Polypropylene Fume Hood

Constructed primarily from polypropylene plastic for superior resistance to chemical corrosion, making it ideal for applications involving strong acids or harsh chemicals.

 

How Fume Hoods Work

 

boka Fume hood

The operating principle of fume hoods is straightforward yet effective. Air is drawn in from the front (open) side of the cabinet, passes over the work area, and is either expelled outside the building (ducted) or filtered and recirculated (ductless). This airflow pattern serves multiple essential functions:

 

  1. It protects users from inhaling hazardous substances
  2. It safeguards experiments from contamination
  3. It protects the environment when exhaust air is properly filtered
  4. It provides necessary ventilation to the workspace

 

Most fume hoods maintain a face velocity of 80-120 feet per minute, creating sufficient airflow to capture contaminants while avoiding turbulence that might disrupt experiments or push contaminants into the room.

 

Modern fume hoods incorporate sophisticated control systems to regulate airflow. Constant air volume (CAV) hoods maintain consistent air volume regardless of sash position, while variable air volume (VAV) systems adjust exhaust volume based on sash opening, providing significant energy savings.

 

The effectiveness of a fume hood depends on proper installation and use. Factors like room air currents, user movements, and equipment placement can create turbulence that disrupts the protective airflow pattern. Regular maintenance and testing ensure continued safe operation.

 

Fume Hood Regulations and Standards

Fume hoods must comply with various regulations and standards to ensure safety and performance. Key standards include:

 

  • ANSI/ASHRAE 110: Establishes methods for testing performance of laboratory fume hoods
  • SEFA 1: Covers recommended practices for fume hood design and construction
  • NFPA 45: Addresses fire protection for laboratories using chemicals
  • ANSI Z9.5: Provides guidelines for laboratory ventilation systems
  • EN 14175: European standard for fume cupboards/fume hoods

 

These standards cover critical aspects such as face velocity requirements, containment testing procedures, construction materials, and safety features. Regular testing and certification ensure continued compliance with these standards.

 

Many institutions have additional requirements based on specific hazards or local building codes. Universities and research facilities often develop their own supplementary guidelines for energy efficiency and safety protocols.

 

Conclusion

 

Fume hoods are essential safety devices in laboratories, providing protection from hazardous substances through controlled ventilation. Their various designs accommodate different applications, from standard chemical work to specialized procedures involving radioisotopes or perchloric acid.

 

If you need a fume hood, Boka is a leading Chinese supplier with extensive industry experience. Our comprehensive range of products can meet diverse requirements, from standard bench-top models to specialized systems for handling particularly hazardous materials.

 

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