A Brief Guide on Fume Hoods for Laboratories!

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Fume hoods in labs commonly deal with dangerous fumes and volatile vapors. Over the years, the construction and style of the fume hood have evolved for the better. Today, you have plenty of options to consider based on your purpose of use. While variations are good, one must understand that each type will be ducted or ductless. Traditional ducted structures connect to the lab’s ductwork to drive the contaminated air out, while the standalone ductless unit filters it to recirculate clean air in the room. There is a lot to check when considering this equipment because lab workers need protection from harmful substances.

Type of lab hoods

If you plan to upgrade your existing facility or design a new laboratory, buy a fume hood based on the workspace and lab functioning requirements. At the same time, the equipment should meet safety standards suitable for a specific setting. A few factors that can help you pick the right thing include fume hood construction, size, usage, efficiency, etc. 

Ducted vs. Ductless Fume Hoods (A choice based on construction)

As hinted, a typical fume hood will either be ductless or ducted. Most modern manufacturers offer ductless laboratory fume hoods or filtered fume hoods. These help your workers and facility stay safe from hazardous fumes through their filtration system. Their built-in filters eliminate toxic air before releasing the same purified air in the room. Since these independent units require no physical connection with the existing ducts in the lab, you get freedom with their placement. Conventional ducted models would depend on HVAC duct connection to push the unsafe fumes out of the building. The duct travels to the roof for the exhaust blowers to extract unwanted particles and gases from the fume hood via the vent to dispel them.

If you wonder what you should opt for, both designs are goal-oriented and purposeful. You could select one over the other by analyzing your specific needs. Suppose you need a structure that is easy to move around the lab. Then, ductless designs will be helpful. However, you must purchase them from a reliable brand or manufacturer because their filters are the main performer. A trustworthy company will use only the best components. Otherwise, the ducted style makes sense because the duct will carry injurious air outside the building.

CAV vs. VAV (A choice based on efficiency)

The next decision will depend on the fume hood’s constant air volume (CAV) and variable air volume (VAV) capabilities. CAV models process the same air volume every time, while the latter uses its smart technology to sense the sash position to exhaust a certain amount of air. VAV can elevate your lab’s green investment by reducing your energy bills. Their upfront cost can be expensive, though. CAV models are also efficient regarding the continuous maintenance of airflow.  

Benchtop or Floor Mounted (A choice based on size)

Walk-in and floor-standing are the other references for the floor-mounted fume hoods. As far as benchtops go, you can also call them tabletop hoods. Tabletop fume hoods stand out for their classic design requiring a table or workbench installation. These varieties are suitable for various procedures and purposes. Some of these can be available in VAV or CAV styles too. Of course, ducted and ductless models are also there. The floor-standing models are big enclosures. Some believe scientists can walk inside this enclosure because of its name, walk-in. However, unlike the benchtop design, this model can fit even large equipment. 

Standard benchtop fume hoods can be 36 to 120 inches in size. Customization can be possible with select manufacturers. You can opt for a bigger model to suit your need. Suppose you pick a 54 inches benchtop fume hood. Its depth can be 34 inches, and its height 48 inches. The width can vary from 36, 48, 60, 72, 84, to 96 inches. Check with the manufacturing company to understand their offers. A few can be more flexible with the design. You can ask them to provide additional elements like electrical switches and outlets, safe lighting fixtures, different styles of sash, vapor-proof lighting, alarm, monitor, etc. These models witness huge demand in medical, R&D, education, automotive, and government industries. They need these fume hoods for battery testing, acid digestion, etc.

On the other hand, floor-mounted options are more specialized. Customization options can be limited, but you can get a few things done, like remote control access for plumbing fixtures, safe lights, ceiling enclosures, etc. Medical, R&D, and education industries need this equipment. How do you choose between these two? Both models are apt for general and multipurpose usage. The main difference is the size. If you deal with larger equipment, floor-based options will be more legitimate.

Factors to consider when selecting a specific fume hood

Ductless and ducted models have their pros and cons. You should weigh your situation before going with anything. A ductless model is a good addition to enhance your facility’s green footprint. Ducted fume hoods may or may not have filters to process the air before sending it outside. As a result, its effect on the environment can be negative. But ductless designs store the contaminants that get safely removed in a landfill. Also, ductless models are versatile because of their portability. However, focus on the filtration system’s lifespan when exploring your option. 

Another critical consideration is budget; buying a fume hood is expensive. Hence, you would like to analyze your need. Ducted models require attachment to the existing HVAC system. If you have everything in place, the ducted model can feel affordable. Otherwise, ductless fume hoods make sense. Apart from the installation cost, you may also compare your choice based on ongoing expenses. For instance, ducted fume hoods will cost more operationally than ductless styles. Ductless designs suck in the air for filtration to release the same back into the facility. The ducted model takes a longer route to achieve the desired goal. 

Things to affect a fume hood’s performance

Fume hoods ensure the safety and security of the people and the facility as they handle several contaminated gases, fumes, airborne materials, etc. But their functionality or efficiency depends on multiple factors. It’s critical to investigate them to ensure a safe environment for technicians and researchers. So, the first point can be the design. To determine whether a specific model can exhaust the contaminated air well, look at the sash handle, baffle arrangement, exhaust port, bypass system, airfoil shape, and aerodynamics. Another essential feature can be the position of the air diffusers, which can be around 1.5 meters from the sash plane to check turbulent airflow. The hood should prevent sending air to itself. Else, it can leak hazardous fumes. If you have ceiling fans in the lab, ensure they are far from the fume hood. It will avoid risks of airflow disruption and potential leakages. 

The exhaust blower is also a vital part of the fume hood. It is the heart of the hood. The ductwork is comparable to blood veins. A fume hood will work efficiently if the ductwork and blower are the appropriate sizes. The fume hood’s velocity depends on the blower’s efficiency. Then, Variable Air Volume (VAV) styles also matter. They contain electromechanical components, which can face wear and tear. One can expect them to suffer failure in three to five years. However, if you maintain your system well, you will only bother about this thing a little. So, keep this component properly. 

Safety protocol adherence for fume hoods

Proper product use is as necessary as evaluating its components from every angle before purchasing. Everyone knows this high-end safety equipment can be the most reliable. But one should also follow the adequate methods of using this system to avoid severe consequences. One error most people make with this equipment is closing or opening the sash too fast. It affects the hood’s airflow mechanism. Please be careful with this part to eliminate the risk of disturbing airflow. You can accidentally spill waste materials on the fume hood. Clean the substance as soon as you notice. Accumulated hazardous substances can threaten your and your facility’s safety.

While experimenting inside the fume hood, you must shut the sash. Partial opening can lead to the release of contaminated vapors and fumes outside. After finishing the work, you must close the sash door fully for the same reason. Then, you can connect electronics from outside the fume hood instead of joining them inside it. It will prevent short circuits and spark risks. Otherwise, it can become another fire or safety hazard anytime. Finally, label all the samples to avoid confusion and side effects.

No matter what type of fume hood you need, the choices are wide-ranging. You must explore them based on your needs to select the right option. Study the product specs, warranty period, and other information. These safety tools are a workhorse, so they are demanding in terms of investment. Choosing something with all the considerations can deliver much more than your expected goals for years. Plus, your facility and workers will feel safe. 

Also Read: R&D Magazine honors Berkeley Lab with 3 R&D 100 Awards



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