Lab Planning 101: There is No Easy Button for Adding a Fume Hood to a Lab
I wish there was a Plug and Play option for adding fume hoods to an existing lab. Whether you’re putting a fume hood for the first time or adding additional hoods, there is no easy button for getting the job done. A fume hood is a critical piece of laboratory equipment that protects users from chemical fumes by pulling air away from the breathing zone at a high velocity. Ventilation rates are regulated by OSHA for adequate protection of the user.
For more on fume hoods, be sure to register for our free Fume Hood Risk Mitigation Digital Conference!
Installing a new chemical fume hood is difficult for several reasons, which often involve both technical and regulatory considerations. Here are the main factors:
1. Ventilation requirements: Fume hoods need lots and lots of air
Airflow: A fume hood is essentially a metal box with power, water, gas, ventilation, and controls hook-ups. The vendor ships the hood, but it’s up to the buyer to take care of everything else. First and foremost, fume hoods require specific airflow rates (typically between 80-120 feet per minute) to ensure that hazardous fumes or vapors are safely drawn away from the user. This requires an adequately sized HVAC (heating, ventilation, and air conditioning) system to handle the increased demand.
Building infrastructure: To add a fume hood, a new vertical duct must connect from the top of the hood and run all the way to the roof to connect to an existing or new exhaust fan system. If there is an existing fume hood exhaust system and fans on the roof, a mechanical engineer or facilities engineer can do an analysis to determine if the system can support the additional load from the new hood. If a fume hood is being added to a building for the first time, then modifications to the ductwork, exhaust fans, and the air handling supply system will be necessary, which can be expensive and complex. Additional disciplines will need to get involved for HVAC modifications. Electrical engineering is needed to safely route power to the new system. A structural engineer may need to be engaged to determine the supporting weight of new rooftop fans,
2. Space and location
Physical space: There needs to be enough physical space in the lab to install a fume hood, with the most common size being 6’ wide and requires adequate overhead clearance of 8’-10’ clear for airflow and safe operation. If you’ve ever popped your head above ceiling tile, you’ll find lots of conduit, pipes, ducts, cable-tray, and other infrastructure. Adding a hood almost always requires re-routing of the overhead congestion which also includes surface mounted obstructions like lighting, air grilles, smoke detectors, and wi-fi antennas. On the walls and floors other built-in items may need to be moved such as electrical and data outlets, gas turrets, laboratory benching, sinks, or other built-in equipment. This may require rearranging or redesigning the laboratory layout.
Delivery: The fume hood comes in one piece as a 6’ wide by up to 3.5’ deep metal box, depending on the manufacturer. Ensure that any doorways and elevators are adequately large enough to take delivery of the fume hood.
3. Regulatory compliance
Safety standards: Fume hoods must meet strict safety regulations set by organizations like OSHA (Occupational Safety and Health Administration) and NFPA (National Fire Protection Association). These regulations ensure that the fume hood operates within safe parameters and minimizes risks to laboratory personnel. The hood itself is a metal box with lighting, power, and gas turrets. It does not pull the air by itself. The exhaust fan, ductwork, and supply air must be designed, air-balanced, and tested to meet safety standards.
Environmental regulations: The disposal of hazardous materials through the exhaust system must comply with environmental protection laws. Any release of chemical fumes into the atmosphere is tightly controlled, and special care must be taken to ensure compliance.
Local municipal permits: In almost every fume hood installation, even when connecting to an existing exhaust system, a mechanical permit is required. Sometimes this can be done with a mechanical contractor—but if modifications are extensive, an architect and structural engineer may need to be engaged. For example, if a new exhaust fan is required, the weight-bearing capacity of the roof needs to be verified by a licensed structural engineer. A large hole would need to be punched in the roof for the new ductwork and then reinforced and waterproofed as part of the installation.
4. Cost considerations
Installation costs: Beyond the price of the fume hood itself (which starts at $10,000 for a typical 6’ fume hood), the installation can be costly due to the need for custom ducting, potential upgrades to the ventilation system, and other construction work.
Operational costs: A new fume hood can significantly increase the building's energy consumption. This is due to the need to provide adequate airflow and make up air to replace the air exhausted by the fume hood, which may necessitate upgrading or replacing the HVAC system.
5. Maintenance and testing
Ongoing maintenance: Fume hoods need regular maintenance, such as verifying airflow and inspecting for leaks, which can add to operational costs.
Performance validation: To ensure safety, the fume hood must be periodically tested to make sure it’s operating correctly and that it is protecting users from hazardous substances.
6. Coordination among teams
Multiple stakeholders: Installing a new fume hood typically requires input from multiple departments, such as safety officers, environmental health and safety teams, building engineers, and lab management. Coordinating these efforts and obtaining approvals can be a lengthy and complex process.
In summary, while adding a new fume hood might seem straightforward, it involves a range of factors from ensuring adequate ventilation to navigating safety regulations, and the process is often complicated by space limitations and significant costs.
For more on fume hoods, be sure to register for our free Fume Hood Risk Mitigation Digital Conference!
All opinions expressed in Lab Planning 101 with Jennifer Swedell are exclusive to the author and are not reflective of Lab Design News.
