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The role of fume hoods and fume cabinets in the laboratory setting

Updated: Sep 19, 2023

Fume hoods and fume cupboards are essential pieces of equipment in many laboratories and industries. They provide a safe working environment for people who handle hazardous materials and chemicals by preventing the release of harmful fumes and gasses into the air.


This article we will explore the basics of fume hoods and fume cupboards, how they work, and their importance in ensuring a safe and healthy laboratory. We will also answer common questions about fume hoods and fume cupboards, including their differences, safety hazards, and requirements.



What is a Fume Hood?


A fume hood, also known as a fume cupboard, is a piece of laboratory equipment that is designed to protect users from exposure to hazardous fumes and gasses. It works by containing and exhausting the fumes and gasses from the laboratory space, preventing them from entering the breathing zone of the user.


The basic principle of how a fume hood works is that it creates negative pressure inside the hood, which pulls the fumes and gasses through the opening and into the exhaust system. This negative pressure is created by a fan located at the top of the fume hood, which pulls air from the room into the hood and then exhausts it outside the building.


One common misconception is that fume hoods and exhaust hoods are the same thing. However, the main difference between the two is that fume hoods are designed to protect users from hazardous materials, while exhaust hoods are designed to remove heat, steam, or odours from a workspace.


Fume hoods are required for any laboratory work that involves hazardous chemicals or materials that can produce toxic fumes or gasses, such as acids, solvents, and radioactive substances. The use of fume hoods is also recommended for any material that may produce dust or particles that could be harmful to the user's respiratory system.



How Fume Hoods Work


Fume hoods use an airflow system to remove hazardous fumes and gasses from the workspace and prevent them from entering the breathing zone of the user. The airflow system consists of a blower or fan that pulls air from the laboratory into the hood through an opening or sash, and then exhausts it outside the building through a duct system.


The airflow in a fume hood is designed to create negative pressure inside the hood, which pulls the fumes and gasses towards the opening or sash, and then into the exhaust system. This negative pressure is achieved by ensuring that the airflow rate into the hood is greater than the rate of exhaust.


The airflow system works to keep the user safe by creating a barrier between the user and the hazardous materials or chemicals. The negative pressure inside the hood prevents the fumes and gasses from escaping into the laboratory and contaminating the air.


However, it is important to note that fume hoods can also pose safety hazards if not used correctly. For example, if the sash is not properly closed, the negative pressure inside the hood may be disrupted, causing fumes and gasses to escape into the laboratory. Additionally, if the exhaust system is not functioning properly, hazardous fumes and gasses may accumulate inside the hood, putting the user at risk of exposure. Proper training and adherence to safety protocols are crucial to ensure safe use of fume hoods.



Where Do gasses from a Fume Hood Go?


Once the fumes and gasses are removed from the workspace and enter the exhaust system, they are directed outside the building. The exhaust system is typically located on the roof or on the side of the building and consists of a fan, ductwork, and an exhaust stack.

There are two types of exhaust systems commonly used in conjunction with fume hoods:

  1. Variable Air Volume (VAV) Exhaust System: This system uses a variable speed fan to adjust the airflow rate to maintain a constant level of negative pressure in the hood. The fan speed is adjusted based on the sash position, which helps to reduce energy consumption and noise.

  2. Constant Air Volume (CAV) Exhaust System: This system uses a fixed speed fan to maintain a constant airflow rate regardless of the sash position. CAV systems are less energy efficient than VAV systems but are less complex and require less maintenance.

Regardless of the type of exhaust system used, it is important to ensure that the system is properly maintained and functioning correctly to prevent the build-up of hazardous fumes and gasses. Routine inspections and maintenance of the exhaust system can help to identify and address any potential problems before they become a safety hazard.



Fume Cupboards


A fume cupboard, also known as a chemical fume hood or laboratory fume hood, is a type of enclosure used in laboratory settings to protect workers from hazardous chemicals or materials.

While fume hoods and fume cupboards are often used interchangeably, there are some differences between the two. Fume cupboards are typically larger than fume hoods and are designed to accommodate larger equipment or apparatus. Additionally, fume cupboards are often used for specialized applications such as biological safety cabinets or clean air enclosures.


The purpose of a fume cupboard is similar to that of a fume hood, which is to protect workers from harmful fumes and gasses that are released during laboratory procedures. Fume cupboards are designed to provide a safe working environment by drawing air into the enclosure and then exhausting it through an exhaust system. The air flow is designed to prevent fumes and gasses from escaping into the laboratory and exposing workers to harmful chemicals or materials.


Fume cupboards are commonly used in laboratory settings such as chemical and pharmaceutical research, pathology labs, and forensic labs. They are an essential tool for protecting workers from exposure to hazardous chemicals and materials, and their use is highly regulated to ensure proper safety protocols are followed.



Fume Extraction Cabinets


A fume extraction cabinet is a type of enclosure that is designed to provide localized exhaust ventilation for laboratory equipment. It is commonly used to protect workers from hazardous fumes and gasses that are generated during laboratory procedures.


Unlike fume hoods or fume cupboards, fume extraction cabinets are not designed for personnel protection. Instead, they are intended to capture fumes and gasses that are generated by laboratory equipment, such as ovens, furnaces, or reaction vessels. The fumes and gasses are then safely exhausted through an exhaust system.


Fume extraction cabinets are often used in conjunction with other types of ventilation equipment, such as fume hoods or local exhaust ventilation systems, to provide a comprehensive approach to laboratory safety. They are particularly useful in situations where fumes or gasses may be generated during laboratory procedures that are not typically associated with hazardous materials or chemicals.


They are commonly used in laboratory settings such as chemical and pharmaceutical research, materials testing, and manufacturing.



Efficiency of Fume Cupboards and Fume Hoods


While fume cupboards and fume hoods are designed to protect lab workers, the efficiency of these devices in providing protection depends on several factors.


One key factor is the design of the fume hood or fume cupboard. A well-designed fume hood or fume cupboard will provide a stable, uniform airflow that captures and removes fumes and gasses from the workspace. This helps to prevent the accumulation of hazardous materials that could pose a risk to laboratory workers.


Another factor that can impact the efficiency of fume hoods and fume cupboards is their maintenance. Regular cleaning, calibration, and inspection are essential to ensure that these devices are functioning properly. Any defects or issues with the equipment must be addressed promptly to maintain their effectiveness in protecting lab workers.


It is also important to note that the efficiency of fume hoods and fume cupboards can be impacted by the specific materials and chemicals being used in the laboratory. Some hazardous materials may require additional measures, such as specialized filtration or ventilation systems, to ensure worker safety.


Overall, the efficiency of fume cupboards and fume hoods in protecting lab techs depends on a range of factors, including the design of the equipment, maintenance procedures, and the specific hazards associated with the materials and chemicals being used. Proper use and maintenance of these devices is essential for ensuring a safe and healthy laboratory environment.



Requirements for Fume Cupboards and Fume Hoods


Fume cupboards and fume hoods must be installed and maintained in accordance with specific regulations and guidelines to ensure their effectiveness in protecting laboratory workers.


The installation of fume cupboards and fume hoods must comply with regulations that outline requirements for ventilation, electrical wiring, and other safety measures. These regulations may vary depending on the location and type of laboratory, as well as the specific hazards associated with the materials and chemicals being used.


Maintenance requirements for fume cupboards and fume hoods may also be regulated by local, state, or national guidelines. Regular inspection, testing, and calibration of these devices is typically required to ensure their continued effectiveness in protecting lab workers. Any defects or issues with the equipment must be addressed promptly to maintain their safety and effectiveness.


Additionally, laboratory workers who use fume cupboards and fume hoods must receive proper training on their use and maintenance. This includes training on the specific hazards associated with the materials and chemicals being used, as well as the proper procedures for working with the equipment.


Fume hoods and fume cupboards are essential equipment for laboratories that work with hazardous chemicals and materials. These devices provide a safe working environment for lab technicians and workers by protecting them from harmful fumes and vapours. However, proper use, maintenance, and installation are crucial for ensuring their effectiveness in protecting laboratory workers.


By following the guidelines and best practices discussed in this article, laboratory workers can work safely and effectively with hazardous chemicals and materials while minimizing the risks to their health and safety.


At all times the design and controls for fume cupboards should adhere to AS/NZS 2243.8:2014.



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