Page 88 - B8773-AEW-XX-XX-PP-A-0001_[P4]_Contractors Manual
P. 88
D R A F T
4.6.2 Extract System
The appropriately sized extract canopy located Minimum standard canopy dimensions are 2.5m
above the oven installed should be connected (D) x 2.0m (W) x 0.55m (H) and constructed in
to a range of ductwork and be complete with welded Stainless Steel.
an axial flow extract fan (or other suitable fan
type) discharging to a convenient location at The size of the oven canopy will increase
high level outside the building. dependant on the type/ capacity of the oven
installed beneath.
The minimum canopy footprint must be 2000 x
2500mm and to comply with DW/172 (for any of The hood should incorporate a gutter around all
the ovens which we currently install). edges with a plugged drain connection at the
lowest point. Removable grease catch pans
As a minimum, the noise level outside the are not required. The canopy must be complete
building shall not exceed NR40 at a distance with at least 4No. removable mesh type grease
of 3m from the discharge point. If required, any filters. Baffle filters are very efficient at grease
sound attenuators used should be suitable for removal but offer a far higher air resistance than
use in a hot, catering extract environment. the mesh type. Domino’s bake-off operation
produces very little grease and the extract
Air resistance should be calculated by the system is predominantly removing heat and gas
Contractor to suit each installation and the fan combustion fumes. Mesh filters are much more
selected accordingly. The selected fan should efficient at removing any fine flour particles
have a duty nominally 20% greater than the which may be caught in the airflow. The filters
calculated resistance of the system but shall should be of a size which will allow them to be
have a minimum duty of at least 1.5m³/sec (or as cleaned in the sinks available in the kitchen.
otherwise specified by the oven manufacturer). The filters should be arranged within housings at
This is to allow for reduced efficiency as the both ends, as part of a plenum system which
system ages and any ‘as installed’ variation in provides balanced extract over the length of
the ductwork resistance. the oven.
The fan should always be mounted on anti- It is important with the modern Middleby
vibration mountings and attached to the Marshall ovens that the extract does not draw
fixed ductwork with flexible connections. The noticeably from only one end, or one side. The
fans should be mounted in such a manner as to traditional filter bank running along the back
be accessible for maintenance and removable edge only, has caused problems in this respect,
in the event of fan failure. so the preferred option, therefore, is a filter
bank running front to back at both ends of the
Under no circumstances may flexible ductwork canopy (not a central double faced filter bank)
be used on the extract system, other than the and joined via suitable ductwork or plenum.
fan connections.
4.6.2 Extract System 3 February 2016
