Air Purification

Grease filtration, smoke filtration and odour control

As standard with our extraction canopies we offer baffle type stainless steel filters which will filter out a large proportion of the grease (40-60%) and can be cleaned in a commercial dishwasher allowing them to be reused again.

​ You may be required by your local county council or planning authority to provide a greater level of grease removal, remove blue smoke associated with grilling or treat nuisance odours which may be getting blown to neighboring properties, We can offer the following solutions to help you meet the planning authority requirements

  • Ozone injection systems / UV-C modules:
  • Activated carbon filters:
  • High efficiency baffle / Cascade filters:
  • Electrostatic precipitator units:
  • Multi-stage filtration:
  • ESP units
  • UV-C units
  • Activated carbon filter

Grease filtration, smoke filtration and odour control: As standard with our extraction canopies we offer baffle type stainless steel filters which will filter out a large proportion of the grease (40-60%) and can be cleaned in a commercial dishwasher allowing them to be reused again.

You may be required by your local county council or planning authority to provide a greater level of grease removal, remove blue smoke associated with grilling or treat nuisance odours which may be getting blown to neighbouring properties, We can offer the following solutions to help you meet the planning authority requirements:

Odour control:
  • Ozone injection systems / UV-C modules: Ozone injection units are used for lighter duty applications where heavy odours are not expected or in conjunction with our systems outlined below to offer a multi-stage filtration system, The Ozone injection units are mounted on the kitchen wall beside the canopy filter plenum and ducted directly into it, a UV bulb within the units generates ozone which is drawn into the airstream in the filter bank and continues to react with the organic compounds that make up the odour through a process of Ozonolysis until it exhausts. This process requires a medium run of ducting to give time for the ozone to react with the organic molecules and break them down. For heavier duty odour applications such as larger kitchens, Indian and Chinese cuisine UV-C modules with bulbs directly in the airstream can be used to treat the air as it passes. The UVC light generated by the bulbs in these modules treats the air initially by a photolysis process whereby the light energy breaks down long chain odour molecules into shorter chain molecules, the UV-C bulbs also generate ozone which reacts with the molecules broken down already by the initial photolysis process allowing them to be more easily oxidised. The combination of both processes makes for a very effective odour destruction system.
  • Activated carbon filters: Activated carbon filters are installed within the ducting normally at the end of the duct run to provide a final “Scrub” of the air in conjunction within one or either of the systems, they also help to remove any remaining residual ozone before the exhaust point. The activated carbon within the cells acts like a large sponge and soaks up odours as they come into contact with the cells, increasing this contact time by having a larger filter or a lower air velocity as it passes through the filter helps treat odours from heavier duty applications.

Grease and Smoke control:
  • High efficiency baffle / Cascade filters: Higher efficiency stainless steel grease filters fitted within the canopy allow for a greater amount of grease (Up to 80%) to be filtered out within the canopy filter bank thus reducing the amount of grease deposits that will build up on the duct walls downstream of the canopy reducing the risk of a duct fire and also reducing cleaning requirements. These type of filters can also be used as a primary stage filter along with the ESP units outlined below to reduce the grease load on the ESP unit. These filters can be cleaned easily allowing them to always maintain the high filtration levels required within the canopy.
  • Electrostatic precipitator units: Electrostatic precipitator units or ESPs are added to the duct run directly into the airstream in either a single pass that offers up to 95% grease/smoke filtration or in a double pass arrangement which offers up to 99.75% filtration. The units work by electrically charging grease and smoke particles within the airstream with a series of Ionizer plates located after a protective pre-filter as they pass them, the airstream then passes collector fins behind the ionizer plates that are negatively charged that attract the positively charged grease and smoke particles which stick to the collector plates then drain down into the sump in the base of the unit. The double pass arrangement is a second suitably sized ESP unit mounted directly behind the first unit which filters the air for a second time so the remaining 5% of grease which bypasses the first filter is then filtered again to a level of 95% which gives a combined total filtration level of up to 97.5% offering almost total removal of all grease and smoke from heavy duty applications.
    Having high efficiency baffle filters and ESPs located close to the canopy removes a large amount of grease which would be deposited on the duct wall downstream greatly reducing the fire risks within the duct and any associated duct cleaning requirements. The units come in module sizes of 2500m3/hr , 5000m3/hr & 7500m3/hr so using a combination of module sizes any extract airflow can be catered for quite easily.

Multi-stage filtration:

Most canopy extract systems require control of grease, odour and sometimes smoke generated from the cooking process within one system so using a combination of the above technologies the extract can be filtered to very high levels to allow customers to comply with any particular guidance.

A typical system would normally be made up as follows:

  • High efficiency baffle / cascade filters – The high efficiency baffle filters act as the primary stage grease filter filtering a large proportion of the grease within the canopy which helps reduce the loading and maintenance requirements of the downstream ESP unit. Having a higher efficiency filter at this stage also eliminates a lot of the grease that would deposit on downstream duct. These filters can easily be removed and cleaned by the customer allowing them to look after some of the system maintenance requirements in house.
  • ESP units- The ESP units would then be connected to the ducting close to the canopy in either a single or double pass arrangement as required and would act as the main grease and smoke filter removing almost all of the remaining grease and smoke from the system protecting the downstream odour control elements and the extract fan, Having a high efficiency baffle filter in the canopy also reduces the grease loading on the ESP units prolonging time between deep cleans.
  • UV-C units – The UV-C units can either be in a duct mounted module fitted behind the ESP units or are sometimes incorporated into the ESP depending on space requirements and expected odour, having the UV-C modules behind the electrostatic precipitator protects the bulbs from the grease in the system which would cover them and reduce the effectiveness of the UV light and also their lifespan. The UV-C light reacts with the organic molecules associated with the odour and acts as the primary means of destroying the odours. The oxidation reaction from the generated ozone continues to remove the odours while they are travelling down the duct towards the activated carbon filter.
  • Activated carbon filter – The last stage of odour control is activated carbon filter cells fitted into an accessible filter housing that absorb odours as they come into contact with the carbon filters. Having the carbon filters immediately before the final exhaust point allows maximum time for the generated ozone to oxidise odours before it is removed by the carbon.

Why have grease and odour control within your system:

  • Comply with DEFRA and local county council guidance on air pollution – The grease and odour from commercial kitchen extraction systems are a large contributor to air pollution in built up areas and can cause major planning issues when located near large residential areas with likely complaints from residents regarding strong cooking smells in the area. With specific guidance in place in the UK in the form of the DEFRA guidelines and also county councils in Southern Ireland becoming more stringent on grease and odour control as part of planning requirements, effectively controlling the grease and odour discharge from a commercial catering extract system is key consideration when designing a new restaurant and its associated ventilation.
  • Reduced fire risk/ Associated maintenance – Grease deposits that build up over time in the ducting and where the ducting exhausts on a building facade or roof present a serious fire hazard when not correctly maintained and cleaned, the reality of the modern commercial kitchen is that often these cleaning requirements are overlooked as the inside of the duct is unseen. Grease build-ups offer a point of ignition for a fire within the duct and surrounding areas and allow a ready source of fuel for a fire to burn out of control. Having an effective grease removal system as part of the extract will leave the duct, exhaust termination and surrounding area free from potential fuel sources for fire. Also keeping your extract fan free from grease will prolong the lifespan and guarantee the performance of the fan for years to come.
  • Health risks for staff and people in the vicinity – Kitchen extract systems contain grease, smoke, odour, effluents from the cooking process and also unburnt flue gas from gas appliances, when this exhausts depending on local weather and proximity to other building ventilation systems it is likely that it will be inhaled by people in the nearby area or people exposed due to cross contamination of ventilation. Normal fresh air ventilation systems would not be filtered to a high enough level to remove the associated smoke and odour particles so are exposed to the adverse health effects this may cause on them. Having an effective odour control system in place can protect staff within the building and also people in the local area from any risks associated with inhaling the smoke and odour. Furthermore with many new businesses worried about the environmental impact of their business on the local community and wider surrounding areas having an effective system in place to control and mitigate their contributions to air pollution levels is a major plus point for their business.