Grease, Odour and Smoke Control Equipment FAQs

Welcome to our Grease, Odour, and Smoke Control Equipment FAQ page! Here, we address common queries regarding the management and mitigation of grease, odour, and smoke in various environments. Whether you’re a restaurant owner, facility manager, or simply curious about effective ventilation solutions, you’ll find valuable insights and answers to your questions below.

Table of Contents

Electrostatic Precipitators

How does an Electrostatic Precipitator (ESP) work?

Air passes through a high voltage ioniser where the grease and smoke particles are given a positive or negative charge; these charged particles are then collected on the neutral plates of a collector cell.

What is the maximum temperature an ESP operates at?

The maximum operating temperature for an ESP is 60oC

What is the pressure resistance through a single pass ESP?

The pressure drop across and ESP operating at design flow rate is 90Pa (dirty)

What is the efficiency of particle removal (%) for single pass, double pass and triple pass?

95% single pass; 99.75% double pass; 99.99% triple pass

Where should an ESP system be installed within the extract system?

Where possible ESPs should be installed local to the kitchen canopy.

How to mechanically install an ESP?

A: For ESPs to work effectively the air passing though the unit needs to support laminar airflow, so the duct connections need to be sized in accordance with DW/144 (22.5-30 degrees). This ensures equal coverage of air across the ESP filters and cells. ESP units should be installed no less than 1 metre away from a bend. Sometimes site constraints mean it is not possible to fit an ESP system local to the canopy, so it is possible to install the ESP externally in a designated plant area.

What maintenance access is required for ESPs?

To fully open the ESP door and remove the ESP collector cells, 600mm is required.

When should double or triple pass (units installed in series) ESP Systems be implemented?

For applications producing high levels of grease and smoke we would recommend double pass ESP filtration.

For applications producing very high levels of grease and smoke we would recommend triple pass ESP filtration

What maintenance is required and why?

Grease and smoke build up on the collector plates which requires cleaning.  Normally this is every 3-4 months, but this depends on what is being cooked.  Care must be taken when handling the collector cells and they must be cleaned using a non-caustic detergent.  Plasma Clean Air offers a professional maintenance package for ESPs to ensure that they keep performing well.

What is the lead time for an ESP?

We generally keep these units in stock but please check with us in advance.

How to clean an ESP filter collector cell in an Electrostatic Precipitator?

The collector cell, or filter, of an electrostatic precipitator is designed for high efficiency removal grease and smoke particles from kitchen extraction systems.  The grease and smoke would otherwise coat the duct surface requiring TR19 cleaning to prevent fire risk, or would escape outside causing a nuisance to neighbouring properties.

To maintain efficiency, the collector cells need to be cleaned.  The filter cells are normally taken away from site and cleaned by soaking in water containing a non-caustic detergent, cleaned using a high pressure hose and left to dry before being QC tested ready for the next service visit.

The service clean and inspection of electrostatic precipitators is carried out by fully trained Plasma Clean Air service engineers.  They arrive at site with a full set of clean ESP filter cells and use these to replace the dirty cells which are taken from site.  During the service visit, the housing of the ESP is also thoroughly cleaned and electrically inspected to ensure the ESP continues to operate at maximum efficiency.

What is an ESP-UV system and when should I use it?

As the name suggests, the ESP-UV combines an electrostatic precipitator with UV for the control of grease, odour and smoke.  It has a small footprint, ideal for when plant room space is limited and low pressure drop compared to passive filtration systems containing panel, bag, HEPA and activated carbon filters.  As a result, it has low running costs as it doesn’t require as much fan power to pull air through the system.

What maintenance access is required for ESP-UV units?


What is a Recirculation Tower and when can I use it?

A Rercirculating Tower or recirculating air filtration system is designed for commercial kitchens where it is not possible to extract to the outside.

It is a complete air handling unit incorporating panel, bag, HEPA and activated carbon filters together with a fan. Kitchen air from the canopy is pulled into the tower where it is treated and released back into the kitchen.  It can only be used with electrical cooking equipment, and it is recommended to incorporate air cooling into the kitchen design.

Recirculation towers are suitable for a range of environments such as shopping malls, pop-up kitchens, high rise buildings, basements and where planning permission has been denied.

What are the ongoing maintenance requirements?

For the system to continue to operate efficiently the filters in a Recirculating Filtration Tower will need to be exchanged when they have reached the end of their lifespan. The frequency of exchange is dependent on the type of cooking as well as the volume of cooking. It is recommended to inspect the system on a regular basis during the first 3 months of installation.

Do I need a Control Panel?

Plasma Clean Air Control Panels are designed to interlock Commercial Kitchen Filtration equipment with air flow.  This prevents the equipment from running when the extraction system is off and stops ozone falling back into the kitchen.   It also saves energy costs by switching the equipment off when the fan is not running.

Plasma Clean Air Control Panels are available in a variety of configurations including Air Flow Interlock, Lamp Life Indicator and Fault Detector options.

Please note that the Xtract series ozone injection units have an inbuilt air flow interlock.

XTRACT Ozone Injection

How does ozone injection work?

Ozone produced by ozonating UV lamps is pulled into the kitchen extraction system by the main fan.  The ozone then acts on cooking odour by a process known as ozonolysis which breaks down the cooking smells.

What size duct is required to connect onto the Xtract 2100 v.2 and Xtract 4200 spigot?


What is the maximum flow rate a single Xtract 2100 can handle?

The Xtract 2100 can handle up to 1.5m3/s; and the Xtract 2100+ can handle up to 2.0m3/s

What is the maximum flow rate a single Xtract 4200 can handle?

The Xtract 4200 can handle up to 3m3/s.

When should you look to supplement the Xtract 2100 with carbon filtration?

If there is insufficient contact time in the duct run, or when you are extracting at low level into a sensitive area

Can I use activated carbon for ozone control?

Activated carbon breaks down ozone (O3) into oxygen (O2) and is used for ozone control in kitchen ventilation applications.  It is recommended to use a minimum of 0.1s dwell time activated carbon for this purpose either in the form of site-safe discard or cassettes with granular activated carbon.

What dwell time should we size our carbons when used with an Xtract 2100?

0.1s when the carbon is acting to remove ozone

What contact time is required for Xtract ozone injection?

Minimum 2 seconds

What is the minimum dwell time for ozone injection when supplemented with activated carbon – 0.1 second dwell time?

1 Second

How to calculate dwell time or contact time? If we have an application where the air velocity in the extract duct is 6m/s - what duct length is required to achieve 2s contact time?

If the air velocity is 6m per second and 2s dwell time is required, the length of duct work will be 6 x 2 = 12m

Where should ozone injection unit be positioned in a kitchen extract duct?

As close to the kitchen canopy as possible to maximise dwell time for ozone to break down the cooking odour.

Is a control panel required with an ozone injection unit?

Plasma Clean Air’s Xtract ozone injection units are supplied with an in-built pressure differential switch to detect airflow. Ozone injection units should not require a separate control panel for standard use.

What maintenance is required for Xtract ozone injection?

As with all equipment, it is recommended to carry out regular inspections during the first few months of installation to understand the impact of the site conditions.

If the air in the environment is highly contaminated, the pre filters will have to be changed often.  Some sites require the prefilters to be exchanged on a monthly basis whereas others require a 3 or 6 monthly exchange.

The ozone tubes require a yearly exchange by trained Plasma Clean Air service engineers.

Is ozone injection suitable for grease and smoke control?

Ozone alone does not act on grease and smoke particles in the airstream.  For low to moderate grease levels it is recommended to employ a Coil Filter in the canopy.  For high to very high levels of grease and smoke, it is recommended to use an electrostatic precipitator located upstream of the Xtract ozone injection unit.

As well as acting on gaseous odours in the air stream, ozone acts on grease which coats the duct, turning it into a white powder.

What is the lead time?

Xtract ozone injection units are generally available for next day delivery.


What UV systems are suitable for kitchen ventilation?

How does UV work for kitchen odour control?

UV lamps used for kitchen ventilation applications produce high intensity UV light as well as ozone.  UV light attacks grease and gaseous odour molecules by a process known as photolysis and ozone continues to treat grease and odour as it travels through the ductwork.

What does Techniclean do?

Techniclean is available as a canopy mounted or duct-mounted UV-C system for odour and grease control.  However if there is a high grease content then it is recommended to use a an electrostatic precipitator in front of the Techniclean Duct Mounted system. This is known as a Combined ESP-UV.

What flow rate can the unit handle?

The Techniclean 5000 unit handles up to 1.4m3/s and the Techniclean 7500 unit handles up to 2.1m3/s.

What is the maximum temperature the Techniclean UV-C system operates at?


What is the pressure resistance through a single lamp frame system?

50 Pa for a lamp rack only

What contact time is required for Techniclean system?

1 second

What contact time is required for Techniclean system when supplemented with activated carbon – 0.1 second dwell time?

0.5 second

When should you look to supplement Techniclean systems with carbon filtration?

If there is insufficient contact time in the duct run, or when you are extracting at low level into a sensitive area

What size are the units?

Our standard short frame lamp unit is the Techniclean 5000 measuring 533 H x 1085 W x 220 D; our long frame unit is the Techniclean 7500 measuring 533 H x 1547 W x 220 D

What maintenance is required?

A fine ash builds up on the UV tubes over time, this needs to be removed using a damp cloth which has been soaked in warm soapy water, followed by thorough drying with isopropyl alcohol.  A yearly service is recommended which includes a full lamp exchange.

What is the lead time?

Techniclean is generally in stock but please check with us in advance.

Does UV treat smoke?

UV systems are designed for odour and grease control and do not act on smoke particles.  For effective smoke control it is recommended to use an Electrostatic Precipitator.

What maintenance access is required for UV systems?

The Techniclean Duct Mounted UV system is often located in a plant room and requires 1100mm for withdrawal of the lamp rack.

The Techniclean Canopy Mount system is withdrawn through the canopy opening and it is important that an operative can get access safely to the canopy located above the cooking equipment.

Coil Filters

What do coil filters do?

Coil filters are installed in the kitchen canopy as a direct replacement for baffle type filters.  They are designed to remove up to 95% of grease particles, dramatically reducing the amount of grease which gets into the extraction system.  This reduces duct cleaning frequency and reduces the maintenance of downstream equipment.

How do coil filters work?

The coils in a Coil Filter cause air to vortex and the oil droplets are spun out of the air stream, coalesce on the coils and collected in the filter.

What flow rate can a standard coil filter handle?

the CF475 handles 0.34m3/s and the CF375 handles 0.24m3/s

What is the pressure drop across the filters?

200Pa at the specified air flow rate

What Coil Filter Sizes are available?

Standard sizes are 495mm x 495mm x 45mm, and 395mm x 395mm x 45mm, bespoke filter sizes available on request, please get in touch.

What maintenance is required?

The stainless-steel filter is washed in warm soapy water or in the dishwasher. Depending on the level of cooking, the filter can be washed daily by kitchen staff or as part of a weekly cleaning routine. Remember that the oil trapped by the Coil Filter would otherwise have found its way into the ductwork, increasing fire risk and requiring routine TR19 duct cleaning.

Do Coil Filters act on smoke?

Coil filters do not act on smoke particles.  For effective smoke control it is recommended to use an Electrostatic Precipitator.

Activated Carbon

What is activated carbon used for?

Activated carbon is traditionally used for gaseous odour control.  It works by adsorbing odour molecules and is available as granular activated carbon or carbon biscuit used in Sitesafe Discarb filters. It is also employed to remove ozone where it acts as a catalyst to break down ozone (O3) to oxygen (O2).

How often should activated carbon filters be replaced?

This depends on the type and volume of cooking and t is recommended to inspect the system on a regular basis during the first 3 months of installation.

From our experience, it is common to replace discarb filters every 4 – 6 months when used as the primary method of odour control. For applications where activated carbon is used in conjunction with ozone injection or UV systems in the airstream, we advise that discarb filters are replaced every 9 – 12 months.

Is additional Filtration required when using carbon filters?

Ideally we would recommend canopy mounted Coil Filters and ESP filtration are positioned before carbon filtration to remove grease and smoke particulate to protect and allow effective odour removal via activated carbon as well as prolong the lifespan. Depending on the application fine  filtration media can also be used (Panel, Bag, HEPA filters).

Passive Filtration

What is Passive Filtration and should I use it?

Passive filters include Panel, Bag and HEPA filters for particle capture and Activated Carbon for gaseous odour and ozone control.

Panel, bag and some HEPA filters are relatively cheap compared to Electrostatic Precipitators but they require frequent exchange which means that the ongoing filter and labour costs mount up.  They also have a high static pressure requiring bigger fans and ongoing fan running/energy costs compared to ESPs.