Fume cupboard

[edit] Introduction

Fume cupboards, fume cabinets or fume hoods provide a contained ventilated environment within a laboratory. Experiments and reactions can take place within the fume cupboard without impacting the air quality in the rest of the lab.

Fume cupboards are mechanically ventilated, typically using PVC ductwork connected to a centrifugal fan and exhausted outside, away from where the fumes can be inhaled.

Recirculating or ductless fume cupboards are also available, these use an internal fan and filter which exhausts the cleaned air back into the room. These are useful for microbiological extraction and areas where extracted air needs to kept to a minimum.

[edit] Components:

• Air flow alarm: Typically an airflow sensor coupled with an audible alarm. This will alert the lab users if the airflow has dropped below a set threshold. This could indicate there is blockage or the extraction system is failing.
• Baffle: Internally mounted panels to aid even airflow and containment within the fume cupboard.
• Bypass grill: Grill on the top of the fume cupboard, this allows a constant volume of air to flow through the fume cupboard whilst the sash is closed or at its lowest position.
• Linings and work-surfaces: These are the internal materials within the fume cupboard. These are typically chemical resistant solid grade laminate (SGL). Other materials such as polypropylene, epoxy resin, glass or stainless steel are also used depending on chemical use.
• Sash: Typically a vertically sliding glass sash on a counterbalance so that the fume cupboard can be opened and closed.
• Services: Socket outlets, water and gas services can be installed within the fume cupboard. Gases and water typically compromise a front-mounted control valve and an internal outlet. This allows control of the service whilst the sash is lowered.

[edit] Terminology

• BS EN 14175: This is the British and European Standard for ducted fume cupboards. This outlines how they should be designed, manufactured, installed and tested.
• Constant Air Volume (CAV): The volume of air extracted is fixed regardless of sash position.
• Containment: A measure of how well the fume cupboard contains the fumes at certain velocities.
• Efflux velocity: The velocity of the exhaust air emitted into the atmosphere.
• Scrubber: A filtration system on the the outlet of the fume cupboard which cleans or neutralises the extracted fumes through the use of water and/or cleaning agents. These can either be built into the fume cupboard or a separate system.
• Variable air volume (VAV): The extraction volume varies according to the sash position. As the sash is lowered, the volume lowers. This is typically achieved through the use of an actuated damper on the extraction outlet of the fume cupboard.

[edit] Related articles on Designing Buildings

• Air conditioning.
• Approved Document F.
• BSRIA Indoor Air Quality TG 12/2021.
• Building services.
• Constant air volume.
• Ductwork.
• HVAC.
• Mechanical ventilation's role in improving indoor air quality.
• Mechanical ventilation of buildings.
• Types of ventilation.
• Variable air volume VAV.
• Ventilation.