Technical terms / definitions
Here are some technical terms and defintions related to fume hoods / fume cupboards.
Average Face Velocity
Average Face Velocity refers to the inbound velocity of the airflow measured in a number of specific positions across the plane of the fume hood sash opening. Air velocities measured in any single position should not change more than twenty percent from the mean.Chemical storage cabinets
Cabinets that are designed to store chemicals safely in a laboratory. Sometimes known as safety storage cabinets.Compensating fume cupboards
Compensating fume cupboards produce more consistent airflow velocities at various sash openings by letting air to enter from a bypass system as the sash is raised or lowered.Containment
Containment is a measure of the efficiency of the fume cupboard in relation to its ability to prevent the escape of any chemical released inside the cabinet. fume cupboards should have a containment of more than a factor of 10 which means that only one particle can escape for every 100,000 released within the fume hood. Containment can be affected by design of the hood, the average face velocity, the air currents outside the hood and scientific equipment being used inside the fume hood.
Ductless fume hoods
Ductless fume hoods that rely on a filter to clean the air before recycling it into the room.
Ducted fume hoods
Fume hoods that rely on a fan system that expels air to the outside though a system of ducts.
Fume extractors
A fume extraction system for removing fumes and particles from a local area or complete building environment. Includes fume filtration systems, fume hoods, laboratory cabinets and fume filtration cabinets.
HEPA filters
HEPA stands for High Efficiency Particulate Air filters used in HVAC systems, vacuum cleaners, microbiological cabinets, biological safety cabinets etc. A HEPA filter is very efficient and removes a minimum of 99.97% of contaminating particles at 0.3 microns in size. To give you some idea of a comparison, a sinle human hair is about 60-75 microns in diameter. Contaminents of less than 35 microns can't be seen with the naked eye. More comparisons - pollen is approximately 10-100 microns and dust is about 0.5-5 micron range. Any contaminating particules under 5 microns can to penetrate deep into the lungs.Hazardous Substance
Hazardous substances inside the hood can be classified by the CHIP Regulations as follows:
1 Very Toxic
2 Sensitising agent
3 Toxic
4 Carcinogenic
5 Harmful
6 Toxic to reproduction
7 Corrosive
8 Mutagenic
9 Irritant
Biological agents such as blood, body fluids and micro-organisms are also covered by this classification, but are not suitable for use in a fume cupboard. (Biological saftey cabinets or microbiology safety cabinets are appropriate in this case.
Make-up Air
Make-up air is the air supplied to a room to replace the air that is removed by the fume cupboard. It is very important that make-up air does not rely on the opening of windows and doors.
Microbiological safety cabinets
Cabinets for microbiological scientific research which protect the user from exposure to dangerous microbes.
Working Opening
The working opening is the size of the opening created when the sash is raised during an laboratory experiment to ensure a velocity of no less than 0.5m/s. It is advised that the working height of the sash in vented fume hood cupboards should not be more than 500 mm.
Read more:
What are fume hoods?
How do fume cupboards work?
What are fume cupboards used for?
Tips on ductless fume cupboards
Tips and advice of ducted fume cupboards
What are ventilated benches?
What are clean benches?
Health and Safety issues concerning fume cupboards
