Exhausting possibilities for kitchen air filtering

Chris Jarman-Brown, global development manager for Purified Air, argues that the industry should not overlook the filtration side of commercial kitchen exhausts.

Commercial kitchen ventilation is often in the news these days as restaurant owners strive to not only improve the working conditions of their kitchen staff but also reduce running costs by incorporating heat exchangers, controlling fan speeds and recirculating air.

What does seem to be overlooked by the industry is the dirty but essential side of the business, tucked away in the plant room or overlooked on the roof: the filtration and control of commercial kitchen exhausts.

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At Purified Air we have been working for over 30 years to develop the most efficient and effective methods of both filtering the oil, grease and carbon (smoke) particulates in the commercial kitchen exhaust as well as controlling the odours.

To this end we have developed a range of electrostatic precipitators (ESPs) to filter the particulates down to sub-micron levels, UV units to generate ozone to nullify the malodorous gases within the duct, along with an odour neutraliser that effectively masks the odours.

So why filter the exhaust fumes from a commercial kitchen in the first place?

In 2005 the DEFRA report on the Guidance on the Control of Odour and Noise from Commercial Kitchen Exhaust Systems became legislation in the UK.

Part of this report dealt with the commercial kitchen exhaust and the filtration required of this to allow a restaurant to open its doors and start cooking. David Collins, Purified Air’s MD, a respected expert in this field, was consulted by Netcen during the compilation the report.

By using electrostatic precipitation, up to 98% of all particulates, oil, grease and carbon (smoke), can be effectively filtered from the extract duct, greatly reducing the build-up of greasy deposits on the inside of the ducting, which not only reduces the frequency of extract duct deep cleans needed but also helps to deter duct fires.

Once this has been done, the malodours within the duct can be treated by either ozone, an odour neutraliser, passive filtration such as carbon blocks, or a combination of the three.

A major factor in specifying a commercial kitchen is space, or more importantly the lack of space, so plant rooms are often squeezed until you can only just swing a cat with a very short tail.

Filtration equipment such as ESPs and UV units are large, heavy and awkward to position safely; they need at least 1metre of space in front of them for servicing, along with adequate access.

In a perfect world all duct runs would be completely straight, 15-20metres long and terminate 1metre above the eves of the building. But we fully appreciate that this is not always possible which is why bringing a filtration expert into the planning discussions as early as possible is so important.

Basically, the more that we can talk throughout the entire process of planning and then building a commercial kitchen the better and more space efficient that kitchen will be.




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