Page 100 - B8773-AEW-XX-XX-PP-A-0001_[P8]_Contractors Manual

4.7.7 Air Filtration
GREASE FILTERS:
• Grease filtration will be provided within the
extract canopy by washable mesh filters
mounted in a filter housing manufactured
from the same material as the structure of
the canopy. Disposable panel type filters
should not be used for grease extraction.
• The most economical filter is the mesh type
which comprises a number of layers of a
galvanised or stainless mesh material within
a stainless or aluminium housing. The filter
relies on the dirty air particles depositing
onto the non-corrodable mesh. This type of
filter is suitable for use in Domino’s where the
cooking is only of the dry bake-off type with
no free oil or grease involved. Mesh filters
that are thinner than 50mm are unlikely to
be effective.
• The performance of the filter varies with
use and temperature and may need to be
cleaned twice weekly to avoid a build up of
debris which increases the resistance to air
flow. When clean, these filters have the least
resistance to air flow (typically 40 pascals.)
• There is no barrier to flame within the
filter, and it is accepted that mesh filters
cannot therefore be used on their own in
applications where there is appreciable risk
of fire. However this does not apply in the
Domino’s operation which only uses hot air
for baking, with no oil or grease being used.
OVEN EXTRACT FILTRATION:
On all projects, a risk assessment of the proposed
oven extraction system should be carried out by
the project Architect in accordance with the
Defra Guide 2005 to ascertain the level of odour
control required (low to medium, high or very
high). This will vary on a site by site basis.
4.7.7 Air Filtration
The Annex C of the DEFRA Guide outlines risk
assessment for odour control for a commercial
kitchen, scoring against 4 key criteria (referred
to as Risk Assessment for Odour Table 1);
• Dispersion
• Proximity of receptors
• Size of kitchen
• Cooking type (odour and grease loading)
The total significance score is then measured
against the relevant impact risk table (referred
to as Risk Assessment for Odour Table 2) to
determine the level of odour control required.
In most instances for Domino’s, where the
extract duct terminates vertically at high level
but there are sensitive receptors within 20m of
the kitchen discharge, a HIGH level of odour
control is required. High level odour control will
usually include fine filtration or ESP (Electrostatic
precipitators) followed by carbon filtration
(carbon filters rated with a 0.2 - 0.4 second
residence time), which may be achieved
through the combined installation of pleated
panel filters, then bag filters, followed by carbon
filters. The exact specification of equipment to
achieve the level of odour control required
must be confirmed with a commercial kitchen
filtration specialist, such as Purified Air.
The Annex B of the DEFRA Guide lays out the
information required to support the planning
application for a commercial kitchen, and will
be completed by the project Architect. When
approved in writing by the Local Planning
Authority, the odour control equipment specified
as a result of completion of the Annex B / Annex
C documents and liaison with the commercial
kitchen filtration specialist MUST be installed in
accordance with the submitted drawings and
supporting information.
3 September 2018