Equipment Leasing Solutions
Lab Safety Equipment
Lab Fume Hoods

How a Laboratory Fume Hood Works & How We Save You Time & Money

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Fume hood diagram

Scientists often work with chemicals, contaminants, and corrosive substances that are dangerous to handle. These materials often give off toxic vapors.

Lab safety equipment

When hazardous fumes are present, it’s essential—and required—that you have the proper environmental protection, regardless of your line of research. Inhaling hazardous material particulates can lead to a litany of health issues.

High efficiency laboratory fume hoods and biosafety cabinets are designed to protect workers by limiting their exposure to these toxic vapors.

Chemical fume hoods, specifically, are a type of biosafety equipment generally suited for a ventilated, enclosed or semi-enclosed workspace. They offer your lab workers a ventilated area where they can work with vaporous materials in a safe, clean environment. All high performance fume hoods do this by pulling air through a sash and over the work area, and then either removing the air or filtering it back into the room.

Most modern units have vapor-proof, see-through polypropylene or polycarbonate front covers or sash windows that sit in front of the ventilated workstation, often including some type of exhaust system to process the toxic fumes.

Duct vs. Ductless Hoods & the Importance of Air Volume

A pair of gloved hands washing themselves

The purpose of a chemical fume hood is to prevent the release of hazardous substances into the general laboratory space by controlling and then exhausting hazardous and/or odorous chemicals.

How that is accomplished can vary, depending on the unit’s configuration. Understanding your ventilation needs, and aligning them with a fume hood’s features, will help you ensure a safe work environment. Learn more about fume hood ventilation techniques below.


In situations where the workspace air cannot be recirculated back into the lab, ducted fume hoods should be used. These enclosures are designed to move the air out of the work surface, beyond the baffles, through a filtration section, and then to the ducting leading outside of the building.

This type of exhaust fume hood is considered the safest and easiest to use, however, it also needs to be installed into your building’s HVAC system. The need for additional ductwork can make this option less convenient for some businesses


Ductless fume hoods filter air and recirculate it back into the workspace, which is why these are sometimes called recirculating fume hoods. Depending on the type of material you are planning to use inside the fume hood, specific HEPA filters will need to be used.

Due to their design differences, these safety hoods are relatively smaller and can be mobile. For increased portability, ductless benchtop fume hoods are an excellent choice, especially those with downflow configurations.

Constant Air Volume (CAV)

The amount of air that flows into your fume hood is extremely important. CAV hoods are designed to ensure that the total volume of air that flows through the fume hood remains constant.

The two main types of these hoods are bypass and non-bypass. Bypass CAV hoods generally have an opening above the vertical sash window to allow for constant airflow even when the sash is closed. The airflow is measured in feet-per-minute (fpm), and is listed in the specs for many high efficiency fume hoods.

Non-bypass CAV hoods, on the other hand, do not have this opening. Instead, they have strict instructions on how much the sash window can be closed while still maintaining proper airflow.

Reduced Air Volume (RAV)

Similar in design and construct to CAV hoods, RAV hoods block off a portion of the bypass opening. This reduces the airflow which in turn reduces the device’s energy use. Due to the reduced airflow, RAV hoods do not provide as much protection as CAV hoods and should be used when working with less noxious compounds.

Variable Air Volume (VAV)

Unlike RAV and CAV, VAV hoods can achieve varying levels of air volume to flow. Some of the most common ways that VAVs change the air volume which comes into the hood are by using either dampers or blowers.

Due to their complexity, VAV hoods can be more expensive than their constant-volume counterparts. However, their energy-saving capabilities make them more cost-effective in the long run.

History of the Fume Hood

Early scientists have been aware of the dangers of inhaling too many toxic fumes for a long time. In the early 19th century, a ventilation system using a hearth, sand bath, and special flues was created to help vent out possibly toxic vapors.

Thomas Edison expanded on the chimney design in what would be considered the first actual fume hood. The University at Leeds would eventually design a fume cupboard in 1923 that would more closely resemble a modern fume hood.

Labconco would eventually begin production of commercially used fume hoods 11 years later. Fast-forward to today, and fume hoods have evolved leaps and bounds. No longer relying on a fireplace to create sufficient ventilation, fume hoods continue to improve and evolve as our demands for laboratory safety increase.

RAV Fume Hood Leases to Fit Every Need

An animated biosafety cabinet

Founder-Friendly Leases

Our lease agreements are founder-friendly and flexible, helping you preserve working capital, strengthen the cash flow of your business, and keep business credit lines open for expansions, staffing, and other crucial operational expenses and business development opportunities.

2-5 Year Lease Lengths

Leases range from 2 to 5 years. Length will depend on several factors, including how long you want to use the equipment, equipment type, and your company’s financial position. These are standard factors leasing companies consider and help us tailor a lease agreement to fit your needs.

Your Choice of Manufacturer

We don’t carry an inventory. This means you’re not limited to a specific set of manufacturers. Instead, you can pick the equipment that aligns with your business goals and preferences. We’ll work with the manufacturer of your choice to get the equipment in your facility as quickly as possible.

Maintenance & Repair Coverage

Bundle preventive maintenance and repair coverage with your lease agreement. You can spread those payments over time. Easily maintain your equipment, minimize the chances something will break down, repair instrumentation quickly, and simplify your payment processes.

End-of-Lease Options

At the end of your lease, you have multiple options. You can either renew the lease at a significantly lower price, purchase the machine outright based on the fair market value of the original pricing, or call it a day and we’ll come the pick up the equipment for you free of charge.

No Loan-Like Terms

Our leases do not include loan-like terms, which can be restrictive or harmful in certain situations. We do not require debt covenants, IP pledges, collateral,  or equity participation. Our goal is to maximize your flexibility. When you lease with us, you’re collaborating with a true business partner.

In-House Underwriting Process

Our underwriting is done in-house. You can expect quicker turnaround, allowing you respond to your equipment needs as they arise. We require less documentation than traditional lenders and financiers and can get the equipment you need in operation more quickly.