Good kitchen extraction systems and ventilation in a professional kitchen is compulsory by law; an exhaust system should always be running when the kitchen is operational. Uncover the basics and make sure you make the right decision when kitting out your kitchen with the help of this simple guide.
The Importance of Kitchen Extraction
When are Kitchen Extraction Systems Necessary?
Basic Types of Extraction
Prime Considerations When Choosing Kitchen Extraction
Sizing Guidelines
Kitchen Extraction Regulations
Extraction, Ventilation and Ductwork Construction
Good Cleaning Practises
The Importance of Kitchen Extraction
Ventilation and extraction systems promote safer more comfortable working conditions and can also improve food safety and hygiene. There are a number of types available, each designed to address a different issue common in commercial kitchens i.e. heat, odour and fumes, moisture and grease.
When Are Kitchen Extraction Systems Necessary?
All commercial operations should have some form of canopy extraction or ventilated ceiling installed. Adequate ventilation is required for any equipment that generates heat, fumes, smells or steam. Kitchen extraction is particularly important when gas appliances are in use to prevent the build up of dangerous carbon monoxide. There is a canopy available to suit every type of appliance and therefore seeking professional expertise is highly recommended to ensure you make a wise investment.
Basic Types of Extraction
Don't let the sheer choice of kitchen extraction confuse you. Put simply;
Extraction Canopies - remove heat
Baffle Filters - remove grease
Condensate Canopies - remove moisture
Filtration Units - remove odours and smells
Each system excels in certain zones within a commercial kitchen, for example, condensate canopies are perfect for warewashing sections while baffle filters are better suited to cooking areas.
Prime Considerations When Choosing Kitchen Extraction
When choosing commercial extraction there a number of areas which need to be considered before making a final selection. Pay attention to;
- Maximum cooking loads
- Quantity, type and size of appliances
- Layout and dimensions of the kitchen
- Number of staff working in each area
- Wall mounted or island positioned equipment
Effective ventilation should;
- Remove fumes and excess hot air
- Filter out contaminants
- Replace extracted air with cool, clean air
- Be easy to clean
- Be quiet and vibration free
- Not create strong air currents which could potentially cause uncomfortable working conditions
The size of the canopy required is determined by the size of the equipment it serves. The type of appliance in use will be directly related to the volume of air that needs to be extracted. A qualified engineer will be able to calculate all of these factors for you.
Sizing Guidelines
As a general rule the height from the floor to the underside of the canopy should measure 2000-2100mm and should not be so low that it causes an obstruction.
An internal depth of 400mm is recommended; any smaller would be inefficient and ineffective, any deeper makes accessibility for cleaning difficult.
When considering work top cooking equipment, the extraction canopy should overhang at the front and on either side a minimum of 250mm. If dealing with combi-steamers or some baking ovens this overhang is increased to 600mm.
A minimum 450mm recommended clearance is advised from the cooking surface to the underside of any grease filter to avoid excessive temperatures or the risk of fire in the filter.
The canopy dimensions, overhangs, air movement, location and mounting height are all directly linked; altering one will adjust the others, generally scaled up at a 1:1 ratio.
Kitchen Extraction Regulations
All ventilation should be positioned where there is a good flow of replacement fresh air available; areas with slow moving, stagnant air are not suitable, being insufficient to adequately disperse fumes. Kitchen extraction systems rely on the sucking in of clean air and the expulsion of unwanted air. Systems will never work effectively if the air supply is impeded or obstructed. 85% of the total extracted air must be replaced to create the negative pressure necessary to effectively limit odours and fumes.
Where new ventilation systems are being installed for gas appliances, it is now mandatory to include 'interlocking'. This involves a gas supply cut out feature between the equipment and the ventilation. If the extraction system fails, the gas supply to the kitchen is automatically shut off. This is not retrospective and only applies to the installation of new equipment.
All businesses will need a record of the kitchens design performance characteristics in accordance with the DW172 Specifications; something which a qualified specialist should be able to help you with.
Extraction, Ventilation and Ductwork Construction
A minimum 304 grade stainless steel is typical for the majority of extraction, ventilation and ductwork however special applications should be 316 grade or higher.
All canopies and ductwork should be fully folded fabrications to eliminate potential dirt traps and to discourage bacterial breeding sites. There should be as few joints as possible with no external fixings. A smooth surface is easier to clean and retains a fully professional appearance.
Good Cleaning Practises
The build up of grease in kitchen extraction and ventilation systems is one of the top 5 causes of commercial kitchen fires. To avoid this hidden danger it is vital to practice good housekeeping. Here are some top tips to consider;
- Ensure there is clear access to all ductwork for unobstructed cleaning
- Avoid corrosive and flammable cleaners
- Grease filters should always be in place and in good operational order to minimise the build up of grease in the ductwork
- Regular checks should be carried out by senior staff with particular attention paid to the condition of metal surfaces and any potential accumulation of dirt, grease or debris around seals and joints
- All extraction and ductwork should be cleaned daily with weekly maintenance and periodic 'deep hygiene' cleaning carried out by a specialist
- Baffle filters should typically be cleaned on a weekly basis
Don't scrimp on good ventilation and kitchen extraction; it not only makes commercial kitchens safer but also a more comfortable environment to work in. In order to make the right decision first time and prevent any costly mistakes, specialist engineers should be consulted from the start of any project with suitable site surveys, risk assessments and commissioning carried out.