Prime Scientific - Ductless vs. Ducted Fumehoods. Which Ventilation Option to Choose

Many laboratory applications require the use of a fume hood to trap and exhaust volatile vapors and hazardous fumes. Fume hood design has come a long way over the past few decades and there are several different types to choose from. Conventional ducted fume hoods connect to facility ductwork, sending contaminated air outside the facility. Ductless fume hoods are standalone units that filter contaminated air, recirculating clean air back into the room.

Ducted Fumehoods

Ducted fume hoods have ventilated enclosures, operate within the framework of your building infrastructure and pull contaminants out of your building through the HVAC system. 

They have a base, work surface, hood, blower and ducting that carries the air outside of the building. The engineer of the heating, ventilation and air-conditioning (HVAC) system needs to determine if your room has enough air to provide the necessary volume of ventilation to the hood.

Ductless Fumehoods

Ductless fume hoods contain filters which clean contaminated air and recirculate it directly back into the laboratory. No additional ductwork is required to exhaust air to the outside. Ductless fume hoods

provide the same filtration capabilities as ducted hoods, but are easier to install, have lower initial installation costs and can be highly efficient.

Many laboratory applications require the use of a fume hood to trap and exhaust volatile vapors and hazardous fumes. Fume hood design has come a long way over the past few decades and there are several different types to choose from. Conventional ducted fume hoods connect to facility ductwork, sending contaminated air outside the facility. Ductless fume hoods are standalone units that filter contaminated air, recirculating clean air back into the room.

Ducted Fumehoods

Ducted fume hoods have ventilated enclosures, operate within the framework of your building infrastructure and pull contaminants out of your building through the HVAC system. 

They have a base, work surface, hood, blower and ducting that carries the air outside of the building. The engineer of the heating, ventilation and air-conditioning (HVAC) system needs to determine if your room has enough air to provide the necessary volume of ventilation to the hood.

So which one do we choose?

Well, to answer this, we need to look into five factors

1. Application

Which chemicals will you be handling mostly in your fumehood? If you are going to work with a very wide range of chemicals which include corrosive substances, then ducted fumehoods are better because their design can resist various chemicals.

Ductless hoods on the other hand must be selected with due care. They have activated carbon filters which are coated with different chemical filters that clean a set of chemicals. Routine and slightly challenging experimentation can be assigned to ductless hoods, after a thorough evaluation.

2. Portability

A ducted hood is a very rigid piece of equipment owing to its bulkiness and fixed ductwork. Ductless hoods are easily portable. They can come with castors too. It is possible to repurpose a ductless hood by changing the chemical filter.

When adding extra hoods to the existing lab, the portability and flexibility offered by ductless hoods offer a great advantage.

3. Safety

It is commonly believed that ducted fume hoods offer the highest safety as the contaminants are thrown out of the lab building. There is virtually no leakage or circulation of contaminants in the lab space. When in doubt, it is best to use a ducted hood.

A ductless hood depends on its chemical filters to clean the air. They essentially have an activated carbon filter to filter most smells and organic matter. For other sets of chemicals, these filters are coated with filtering reagents.

4. Energy Consumption

Because of the ductwork and blower etc., a ducted hood consumes a lot more energy.

On the contrary, a ductless hood filters air and recirculates the clean air back to the same space. It consumes much less energy and puts virtually no burden on the HVAC system.

5. The Environment

The energy consumed by a ductless hood is much less, say just 30% of the ducted hood. So, if environmental concerns are paramount, each fume hood must be carefully selected. A ductless hood will offer much less energy consumption and win precious carbon credits for your lab.

Conclusions

In the end, it all boils down to your needs in the lab. If, for example you work with hazardous chemicals like a hydrofluoric acid and perchloric acid then it would be more reasonable to use ducted hoods. On the other hand, if you are working with other chemicals like organic solvents and corrosive agents then ductless fumehoods are better.

Furthermore If energy consumption is a concern then the ductless hoods consume less energy than would be consumed by ducted hoods.

In any case these choices are made by the lab manager after careful and meticulous planning during the design of of the laboratory; while carefully detailing all the types of chemicals and agents that will be used during the lab's operation; and weighing all the pros and cons discussed above, thereby making an informed decision after considering all the different aspects.

References

1. https://www.labmanager.com/comparing-ductless-vs-ducted-fume-hoods-28187

2. https://www.google.com/amp/s/resources.workstationindustries.com/blog/ducted-fume-hoods-vs-ductless-fume-hoods%3fhs_amp=true

3. Ducted Vs Ductless Fume Hoods: 5 Tips to Make the Right Choice

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