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

Excedr - Laboratory Fume Hoods

Excedr’s lease program can source all instrument types and accommodate any brand preferences your end-user might have. Request an estimate today and see how leasing a lab fume hood can simplify equipment procurement and balance sheet management.

All equipment brands/models are available

The Advantages of Excedr’s Fume Hood Leasing Program:

  • Eliminates the upfront cost of purchasing equipment by spreading its cost over time
  • Minimizes equipment downtime with included complete repair coverage and preventive maintenance
  • Takes advantage of potentially 100% tax deductible* payments, providing you significant cash-savings
  • Expedites the administrative work needed for instrument procurement and logistics
  • Conserves working capital,  enabling you to reinvest in your core business and operations (staffing, inventory, marketing/sales, etc.)
  • Accommodates all manufacturer and model preferences

*Please consult your tax advisor to determine the full tax implications of leasing equipment.

a pair of safety goggles above a lab coat with gloves by the ends of the sleeves

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

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

two hands washing with soap and water

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

a fume hood on wheels with the opening facing forward

Your lab may be working with dangerous chemicals or materials that produce noxious fumes unsafe to those present. If so, it’s essential to have the proper safety equipment. If you’re interested in financing a fume hood, or want to lease a biological safety cabinet, get in touch with us to learn more about your options.

Already have a model in mind? Did the manufacturer provide you with a quote? Request a lease estimate today and we can create a custom estimate tailored to your financing needs.

Operating Lease

This off-balance sheet financing structure provides three options at the end of the term. The lessee has the option to return the equipment to the lessor, renew at a discounted rate, or purchase the instrument for the fair market value. Monthly payments are also 100% tax deductible which yields additional monetary savings.


If you recently bought equipment, Excedr can offer you cash for your device and convert your purchase into a long-term rental. This is called a sale leaseback. If you’ve paid for equipment within the last ninety days, we can help you recoup your investment and allow you to make low monthly payments. This also frees up money in your budget rather than tying it down to a fixed asset.

Fume Hood Manufacturers & Models
Learn More

Thermo Fisher & Applied Biosystems






Roche Life Science

Analytik Jena


Operating Capital Benefits

Operating Capital Benefits

Excedr's operating lease structure allows you to keep your business credit line open for expansions, staffing, and other operational expenses. Additionally, it strengthens the cash flow of your business and keeps cash reserves free for business development opportunities.

Effects on Credit

Effects on Credit

Leasing / renting provides you with non-dilutive financing and does not hinder your future borrowing ability. You're able to acquire the equipment you need without the baggage associated with traditional financing.

Speed of Approval

Speed of Approval

Excedr's program allows you to respond quickly as your need for equipment and technology arises. You can be approved with minimal documentation and have the equipment you need in operation and generating revenue for your business quickly.

Refurbished Equipment

Refurbished Equipment

Unlike traditional financing and leasing companies, the Excedr program can accommodate refurbished equipment in addition to demo units. If you are looking for additional cost-savings, we recommend considering this option.