Mr S Patel
124 – 126 Tredworth Road
Further to our recent visit to you property to discuss Extraction Flue Systems and site
I am pleased to give my recommendation of the Odour Emissions System.
This specification covers standards for the selection, supply, delivery, installation,
testing and commissioning of Kitchen ventilation. The cooking of food involves
appliances releasing heat, steam, fumes and airborne grease. The cooking process
requires extract ventilation for the removal of fumes, smoke and vapors generated by
the cooking activity.
To provide an acceptable working environment for all kitchen staff by the
extraction/removal of heated air, fumes, steam and cooking smells, as well as
preventing condensation. The extract canopies are designed to enable ease of access
for cleaning throughout the system and distribution ductwork and primary fan
All fumes and odour from the food preparation areas of the kitchens shall be
mechanically extracted utilizing an extract canopy specifically designed and installed by
a nominated specialist to remove all cooking odour. This will take into account the
dimensions of the kitchen in question, the type of grease filters used in the application
and the cooking equipment within the grouped cooking range.
All fan equipment, ductwork and filter housing shall be so mounted and installed so as
not to give rise to a noise nuisance. Any noise generated by the extraction or supply
systems as a whole shall not exceed the pre-existing hourly background noise level at
nearby residential accommodation by more than 5dB(A). When measured and rated in
accordance with BS 4142, entitled Method of Rating Industrial Noise Affecting Mixed
Residential and Industrial Areas 1990.
Unit 2B, Gregories Mill Street, Worcester, WR3 8BA
Tel: 07970254977, email:
Extraction canopies will be sited over the cooking equipment, or any heat, steam or
grease producing equipment.
Three Stage mixed media filter system
Our recommended unit for odour emissions is the three stage mixed media Filter System The
filter will act as the second and third stage of filtration, (the first being the canopy/fryer filters).
This would only leave resultant odour that were not encapsulated in particulate but are in
gaseous or vapor form, which can be dealt with by using our Mixed Media Filters.
We would expect odour emissions to be reduced by up to 65% from a system incorporating
the above equipment. However, the canopy filters and grease trap must be cleaned on
frequent basis, also a regular maintenance regime implemented, to avoid the long chain
fatty acid effect, which increases odour significantly.
Fan Equipment
Fans are to be adequately sized to overcome the system resistance and to provide the
required Extraction / supply rate specified. 500mm diameter turbo Prop fan will be used.
Which measured from 3m distances will produce a typical sound pressure level of 70dba, in
free field conditions ie before any additional ducting or silencers have been fitted.
Using two attenuators (silencers) 500mm long with a 80mm wall pad. One will be used
before the fan and one after the fan. Both silencers will reduce the sound level of the fan
motor from approximately 70dba to 45dba.
On the stack discharge point the sound level is expected to be approximately 40dba and will
be discharged vertically with a high velocity cowl.
The fule is as we consider to be appropriately designed and positioned to avoid
unreasonable effects and we believe would not harm the residential amenity of neighbors
from noise and odour as the noise level would considerably be reduced by the attenuators.
Grease Filters
Extract canopies will be fitted with internal extract plenum(s) with grease filters cells
across their length. The filters should be of a sufficient size and number to ensure that
the velocity through them does not lead to grease “carry over” into the ductwork and
onto the extract fan.
Design of the extraction flue system
The system has been designed in a manner, which will firstly create the maximum potential
effectiveness for airflow from the inside of the building to be pushed outside. The
equipment and design used for the extraction system will enable the smoke fumes from
inside the shop to be extracted so that there are reduced fumes within the premises and
also pushed high enough outwards so that it will not create any offence or harm to
neighbors or passing public.
Unit 2B, Gregories Mill Street, Worcester, WR3 8BA
Tel: 07970254977, email:
The ducting pipes, which are manufactured from galvanized steel, can be painted if
necessary in order to resemble the building itself.
Fresh Air
Unit 2B, Gregories Mill Street, Worcester, WR3 8BA
Tel: 07970254977, email:
1. Carbon Cell
2. Silencer ᴓ500mm
3. TCBBx2 ᴓ500mm Extraction Fan
4. High Velocity Cowl
Canopy with Baffle Filters; L: 4000mm D: 1100mm, Back: 500mm
Canopy Extraction system Calculations
Type of Extract Hood:
Wall Canopy 430 Grade 0.9mm S/Steel, with 495*495*495
S/Steel (GFB) Grease Baffle Filter
Face Velocity across Extraction Hood:
Hood Length: 4m x Depth 1.1m = 5.1m/2
Face Velocity: 5.1m/2 x 0.51m/s (Heavy Cooking) = 2.60m3/s (design Volume)
Duct Air Speed:
Duct Dimension: 0.5 x 0.5 = 0.25m2 (air Across Duct Section)
Design Duty: 2.60m3/s – 0.25= 9.8m3/s
Carbon Filter Calculations:
Activated Carbon Cells H/Duty 600*600*600 @ 0.9m3/s Volume equates to (0.1 Sec Dwell)
Design Volume: 3.54m3/s – 0.9m3/s = 3.9 Cell required)
Unit 2B, Gregories Mill Street, Worcester, WR3 8BA
Tel: 07970254977, email:
To achieve double dwell time: 0.1 = 3.9 cells + 3.9= 7.8 cells giving a total contact time of 0.2secs
(200PA Clean Air)
Discharge flue efflux velocity calculations:
500mm diameter = 0.196m2
design Duty: 2.60m3/s / (0.196) = 13.2m/s
Unit 2B, Gregories Mill Street, Worcester, WR3 8BA
Tel: 07970254977, email:
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