When working in a laboratory environment, it’s not only important to have a properly functioning fume hood at your disposal and a lab worker that knows how to use it, it’s crucial to have the right one for your intended use in order to ensure the safety of everyone in the lab.  

Choosing a Fume Hood

Lab workers put themselves at risk in many situations in order to conduct the necessary experiments that make their discoveries possible. Since exposure to air-borne chemicals and inhalation of those chemicals can be of particular danger to human scientists, fume hoods have become an absolute necessity to laboratories all over the country.

There are three main types of fume hoods that are used by today’s labs, although some prefer to create a custom fume hood that will fit more perfectly into the design of their lab and their specific application. Before we delve into deciding which fume hood is right for your laboratory, let’s first explore why we use lab hoods and how they work, so you can get a better idea of what you’ll need for your specific type of work.

The Purpose of Fume Hoods in a Lab Setting

Harmful Chemicals

To put it plainly, fume hoods allow scientists and chemists to work with potentially harmful chemicals without fear of accidental exposure or inhalation. Inhalation of a gas resulting from a chemical reaction can cause serious problems, without proper ventilation, and a fume hood ensures that those working in a laboratory environment can redirect vapors, fumes, and gases produced by the compounds they work with.

How Fume Hoods Work

By drawing air out of the room in which they’re installed, fume hoods are able to instantly create a vacuum that sucks the fumes and gases up through the fume hood, itself, and through to a duct that leads to outside ventilation. This means that, if a chemical reaction happens, all that lab worker would need to do would be to duck under the sash and operate the fume hood to displace the potentially harmful gases.

Airing Out the Room

Most, if not all, fume hoods have a clear sliding window on the sash that protects from injury due to fires, splashes, and even small explosions that may occur under the fume hood. Keep in mind, fume hoods are not meant for use with biological agents or nuclear materials. In those cases, you’ll need specialty safety cabinets designed to protect against those specific things.

The fume hood also dilutes the room’s air, and, specifically, the air in the area under the fume hood, with fresh air from the outside that helps protect lab workers from additional exposure. In the event that the laboratory does not have any additional ventilation (as some labs do), a fume hood can mean the difference between life and death for some scientists.

Correct Fume Hood Usage

Correct Fume Hood Usage

Regardless of the type of fume hood you get, it won’t matter if your lab workers don’t use it correctly. In order to ensure that you’re using your fume hood to the height of its potential, be sure that your lab workers:

Perform all of their duties pertaining to volatile or hazardous materials under the fume hood.

Keep the hazardous material at least 15 centimeters away from the main opening of the fume hood.

When boiling materials or doing an experiment where splashing may occur, use the sash as a shield to protect yourself.

Keep all electrical devices that could spark a fire outside of the hood.

Try to keep the fume hood away from any cross drafts or air currents that could potentially undermine its purpose.

Ensure that the fume hood is working properly and is free from any damage before use.

When the fume hood is not activated, ensure that any dangerous materials are in sealed containers.

Ensure that you have a plan of action if an emergency happens. You don’t want to be stuck with a bunch of hazardous chemicals during a blackout without a functioning fume hood.

Different Types of Fume Hoods

Different Types of Fume Hoods

Now that you know how to use a fume hood correctly, it’s time to pick out the perfect fume hood for your lab. It’s important to get a quick overview of the different types of fume hoods that are out there and what they do so you can decide for yourself which product is right for your setting and budget.

Ducted Fume Hoods – Ducted fume hoods are considered to be the most “traditional” form, as they are also the most straightforward. Very effective, these installations need to be melded into the laboratory’s existing air duct system. In many cases, certain areas of the building’s exhaust system will need to be rendered immobile in order to make the fume hood work properly and safely.

Preventative maintenance will need to be administered in order to ensure that nothing clogs or blocks the duct, and make-up air systems may even need to be put in place to compensate for the air consumed by the ducted fume hood

In short, a ducted fume hood can prove to be an expensive venture, and it can also be a large consumer of energy, though recent improvements (like redesigned sash openings and restricted openings during use) and technological revolutions have made these fume hoods more accessible to laboratories everywhere.

Ductless Fume Hoods

Ductless Fume Hoods – Ductless fume hoods rely on neutralizing agents and filters to make the dangerous chemicals less harmful. In these cases, you’ll need to understand exactly the type of material you’re working with and what will counteract its negative effects.

Ductless hoods were inspired by gas masks that rely on activated carbon technology to neutralize threats. By using this same concept, a ductless fume hood is able to eliminate the threat the pollutants pose by simply neutralizing them within the laboratory atmosphere. This means that no additional ductwork, suction, or HVAC technology is needed in these types of hoods.

Because a ductless fume hood does not dispense chemicals directly into the environment, it is also thought to be a much more environmentally safe alternative to traditional ducted fume hoods. It also does not generate a great deal of energy, unlike ducted fume hoods.

A ductless fume hood will require more maintenance costs in the form of filter changes. This occasional duty can be performed easily by a lab assistant with minimal training. However, these filters do not cost nearly as much as the initial duct construction often required for ducted fume hoods. Also, ductless hoods offer a lot more in terms of mobility since they only require electric power and table space.

Filtered Fume Hoods – Filtered fume hoods take the best of both worlds from both ducted and ductless fume hoods. By providing a litany of detection, communication, and filtration technologies, a filtered fume hood can prove to be the high-tech solution that you need. Filtered frame hoods use their advanced filtration media to capture a wide range of fumes, gases, solvents, bases, and acids simultaneously. Because of this, most filtered fume hoods offer a single filter type to ensure that you don’t accidentally pick up the wrong one for your purposes.

Not only that, most filtered fume hoods utilize enhanced sensors to determine if chemicals are breaking through the hood’s primary filter. Once detected, the fume hood communicates to lab workers through the use of safety alarms. It will even contact other departments via Ethernet, BACnet, or other communication protocols.

Thanks to the machine’s automatic saturation detection system, lab owners all over the country have witnessed the many advantages presented by filtered fume hoods. Not only that, but lab workers currently working with ductless fume hoods may feel safer when using a system that literally watches their back for them and which will be instantly compatible with the type of work they do.

Lab Safety

As one of the most important pieces of equipment related to worker safety, using the correct fume hood for your laboratory’s purposes can prove to be a life or death decision. Be sure to make it wisely.


  1. http://blink.ucsd.edu/safety/research-lab/chemical/hoods/#Limitations
  2. https://smah.uow.edu.au/content/groups/public/@web/@sci/@chem/documents/doc/uow059174.pdf
  3. http://www.rdmag.com/article/2013/12/safety-and-sustainability-factors-fume-hoods