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Commercial kitchen exhausts and air filters

Here are some of the most frequently asked questions about air and odour management and exhaust systems in food premises and coffee roasters. But if you can’t find your answer here, please don’t hesitate to call our expert team at Air and Water Filtration Solutions in Australia and New Zealand on +61 2 8231 6500.

Exhaust hood systems

What is the maximum amount of air that can be recirculated into the hood after it has passed through an EK Series electrostatic filter ?

Up to 60%. But still check with your hood designer! After that, smoke and fumes from the cooking may start leaking from the hood.

Electrostatic filters

How efficient are EK Series electrostatic filters?

Very efficient. The AAWFS EK Series electrostatic precipitator  will remove grease, oil, mist and smoke particles up to micron 0.01, and keep the exhaust duct clear of these flammable pollutants. And with an electrostatic air filter your ducting doesn’t need to be cleaned nearly so often – resulting in big cost savings as well as a reduced fire risk.

What about the resistance of the filters in terms of airflow?

The static resistance of the EK Series filter is a very low – 20 Pascal (Pa)

How often does the filter need servicing?

About once a fortnight on average. If you use chargrill or charcoal cooking, cleaning should be carried out once a week.

What happens to the grease and smoke particles?

They slide down the filter plates and drop into a cleanable tray beneath.

Does AAWFS do the cleaning of the cell and tray?

No. Your installer can suggest accredited cleaning companies. The same company can also clean your honeycomb filters.
However, you can easily empty the grease tray yourself, and if you have a soaking tank like an OZ-Tank, or other brand, you can clean  the electrostatic cell yourself if you prefer.

What EK Series ESP sizes are available?

AAWFS electrostatic air filter range from 500 litres per second up to any size you need. There are three basic models. These can be arranged in parallel to increase airflow or in series (increased filtration) configuration according to your specific requirements.

What should the velocity (air speed) of the airflow be through the ESP?

For the best filtration efficiency, we recommend 3 metres per second (3m/s) through the ESP, although up to 4 m/s is acceptable depending on the type of cooking.

When is a double pass needed?

You’ll need a double pass or double filtration when your cooking process produces a lot of smoke – e.g. chargrilling – or if your point of discharge is close to a busy footpath or walkway.

Where’s the best spot to install my ESP?

The filter should be as near as possible to the exhaust hood. This way you will greatly reduce the cleaning of the duct afterwards as well as reducing fire risk level.

Ozone generators

What is ozone?

The molecule ozone is nature’s own powerful air purifier and odour oxidant, produced only under extreme circumstances; for  example, thunderstorms. This is why the air smells so fresh and clean after a storm. Ozone is sometimes called super-charged oxygen. Oxygen is O2; Ozone is O3.

How do AAWFS ozone generators produce ozone?
OZ-O3 Series ozone generators   work on the highly efficient corona discharge system. The airflow is pushed onto ceramics that have a high magnetic charge. Oxygen is then changed to ozone.

Is ozone safe?
Residual ozone produced by the ozone generator reverts to oxygen 20 to 30 minutes after reacting with odours and being dispersed into the atmosphere. The discharge should never be released straight onto people, as it can be harmful to children and those with respiratory disease. Ozone should not be used indoors in large quantities when human or animals or even plants are present. If ozone is used in concentrated form indoors to kill mould, germs and odours then doors and windows should be open for 20 minutes before normal use of the premises is resumed.

What about maintenance of my OZ-O3 ozone generator?
AAWFS OZ-O3 Series ozone generators require very little servicing, (unlike UV lights that need to be cleaned when covered with oil mist). Once a quarter, simply vacuum or brush the dust that may have accumulated inside the unit. The first time you clean it you’ll get a fair idea of the cleaning frequency needed at your location.

How is the OZ-O3 connected to the exhaust duct?
A PVC pipe is connected between the ozone generator and the ducting, as close as possible to the hood, after the ESP is fitted.

Can my OZ-O3 be installed outside the building?
No, the ozone generator should always be placed inside. The PVC connection pipe can be up to 8 metres long.

Is there a minimum contact time between ozone and odour?
Yes, the ozone and the odour have to be in contact for 2 seconds for good efficiency. Adjusting ducting lengths or velocity will facilitate this. For example, if you have a velocity of 3 m/s you need 6 m of ducting from the O3 injection point.

How do I switch the OZ-O3 on?
Your ozone generator should always be interlocked with the fan. It should never be operating when the fan isn’t running.

Can the ozone rust the ducting?
No, because the period when the ozone is very concentrated is when it travels through the PVC pipe. Once it’s mixed with the air in the ducting it quickly dilutes to low concentration within the exhaust duct.


What kind of fans do you supply?
AAWFS-recommended centrifugal fans are very powerful and quiet, and don’t need silencers. Our AAWFS strategic alliance with Aerovent gives you a large selection of fans at great prices.

Other queries 

 What information is needed to quote on a job?
Your hood supplier will need to know:
•    Your cooking type and equipment.
•    The length of the exhaust duct to the discharge point.
•    The location of the discharge point.

Where do I find further information on exhaust systems?
Have a look at our detailed 3-D animations  on this website. You’ll find the right package and ventilation system to suit your cooking, kitchen and outlet circumstances.

Do AAWFS have distributors?
No – we sell directly to the fitters at distributor prices. That’s why Air and Water Filtration Solutions is able to charge such extremely low prices, right across Australia and New Zealand. We import exclusively from the factory, keep our operating costs low and then pass on the savings directly to our customers. All fitters registered with AAWFS receive distributor prices.

Are you able to help us with development applications?
No, AAWFS only supplies equipment, but your contractor should be able to give you all the information you need to write an application for council approval.

Contact Air and Water Filtration Solutions today

If you’d like to learn more about our industrial air filters and commercial kitchen exhaust systems, please use our contact form.

Or call our expert team for Australia and New Zealand on +61 2 8231 6500