Guidance on the Control of Odour and Noise from ... - Defra

4.7 Odour Abatement Tools
Odour emissions from kitchens arise from odorous chemicals that are either too
small to be trapped by coarse filtration or are present in the gas phase. The degree
and type of odour control required is dictated by:
• size of the cooking facility;
• type of food prepared; and
• location of the premises.
The greater the potential risk of causing harm to the amenity or causing a nuisance
the more effective the odour abatement must be. In certain circumstance where local
planning requirements restrict the use of tall stacks more emphasis must be placed
on odour abatement.
4.7.1 Coarse or Grease filtration
Filtration can be provided by either washable or baffle type of filters and are usually
positioned at the point of extract within a filter housing. Disposable grease filters
should not be used. A range of coarse filters are available and the characteristics of
these filters are summarised in Table 4.5.
Table 4.5 Summary of characteristics of some common coarse filters
Filter
Type
Recommended
Face Velocity
(m/s)
Typical
Efficiency
*
Mesh 2.0-5.0 40-50%
Baffle 4.5-5.5 (at slot) 65-80%
Cartridge 4.5-5.5
(at entry)
Water
Wash
Cold
Water
Mist
4.5-5.5
(at entry)
4.5-5.5
(at entry)
90-95%
90-95%
90-98%
Advantages Disadvantages
Inexpensive
Low pressure drop when
clean
Inexpensive
Non-overloading pressure
drop
Higher efficiency
Non-overloading pressure
drop
Higher efficiency
Non-overloading
Low maintenance
Very efficient
Non-overloading
Low maintenance
52
Grease held in air
stream
Variable pressure
drop
Potential fire hazard
Higher pressure
drop than mesh
filters
High pressure drop
Special plenum
fabrication required
Expensive
Very high pressure
drop
Hot water supply
and drains required
Expensive
Very high pressure
drop
Hot and cold water