Knowledge Base

– Information and tips to achieve a modern, safe and energy efficient commercial kitchen.

Fatty and dirty exhaust air is associated with costs. If purified, it would be a valuable resource. Our vision for the modern commercial kitchen is a kitchen that consumes significantly less energy while still offering better fire-protection, a safe and healthy work environment and little to no impact on nearby residents. In short: A kitchen in harmony with its surroundings.

Purified air can become a valuable resource.

Odor Reduction – Less Disturbing Cooking Odors

In addition to increased fire protection and efficient energy recovery, odor reduction is one of the main reasons for using ozone-based air purification.

  • Continuous and reliable purification of air with ozone reduces the emission of cooking fumes considerably. This in turn reduces possible risk of complaints from neighbors who may be disturbed by the smell
  • Requirements for odor reduction are much greater if the exhaust duct is positioned close to residential buildings. In these cases, a final carbon filter should be considered.


In urban areas, ozone purification of exhaust air can be the difference between obtaining permission or not for running a restaurant business.

Fire Safety – Safer Commercial Kitchens

A direct consequence of ozone purification of a commercial kitchen exhaust air is that fat is reduced as well as increased fire safety due to less fat deposits in the kitchen flue.

With a built-in exhaust air cleaning system you reduce the fire hazard and may, depending on the local fire code, use less costly channel materials in the installation. At the same time it reduces the need for chimney sweeping since the channels will be much cleaner.

Reduced Fire Hazard with Ozone Treatment

Three things are needed for a fire to occur; fuel, air and heat. All three factors are present in a hood/exhaust duct filled with fatty high energy air above e.g. woks, deep fryers and frying table. Remove one factor and the fire hazard is reduced.

Ozone is effective in reducing fat in the kitchen flue. This prevents build-up of energy-dense, fire-prone fatty deposits in the ventilation duct and minimizes the fire hazard.

Extinguishing System

Fire extinguishing system with liquid extinguishing agent can be installed in kitchen hoods and protects personnel and further reduce the risk of an open flame developing into a fire.

Regular Supervision

With a built-in exhaust air cleaning system you reduce the fire hazard and may, depending on the local fire code, use less costly channel materials in the installation. At the same time it reduces the need for chimney sweeping since the channels will be much cleaner.

The frequency which a canal must be inspected and cleaned must be decided from case to case.

Energy Recovery

Energy efficiency is achieved through a combination of measures and, according to studies, those affecting the ventilation have the greatest impact:

  • Technology in the kitchen
    • Choose energy efficient equipment and machinery
    • Use equipment that allows for Demand Control


  • Ventilation


  • Cooling
    • Efficient refrigerators, freezers, etc.
    • Replace cooling of e.g. garbage rooms with other technologies


  • Maintenance
    • Regular equipment maintenance helps to maintain high efficiency and thus lower power consumption


  • Staff training
    • Educate the staff! Kitchen staff’s use of the equipment has a major impact on the energy consumption


Studies show that the greatest savings potential is in these areas, where measures for the ventilation are by far the most important.

Security & Safety

In addition to the fact that fire safety increases, as discussed above, there are some additional factors that shall be considered in conjunction with ozone and equipment in the kitchen environment:


Safety Precautions

Ozone is a powerful air purifier that must be handled with respect and responsibility. We always recommend that ozone installations are fitted with pressure switches and ozone sensors (ozone alarm/monitor):

  • Pressure Switch
    • Control the operation of your ozone generator/ozone system with a pressure switch
    • The pressure shuts off the ozone system if the exhaust fan is not in operation (i.e. no flow/pressure)
    • The ozone generator cannot start if the fan does not generate an airflow
    • Another option is to control ozone system via the ventilation fan

  • Ozone Sensor (ozone alarm/monitor)
    • Ozone sensors measure the ozone concentration continuously in ambient air
    • Ozone sensors turn the ozone system off in case of levels exceeding allowed limits for ozone
    • Read more about ozone sensors / ozone monitors / ozone alarms


These preventive measures will help to protect the staff against ozone exposure in case of malfunction.

An ozone sensor is preferably placed in the kitchen as well as at the place where the equipment is located if not placed in the kitchen. This is especially important if the equipment is located where it is exposed to external influences.

More About Ozone Sensors and Ozone Measurement

There are two different types of measurement techniques for ozone; Either UV photometers, which costs from EUR 5 000 and upwards or a semiconductor technology available from less than hundred euros up to EUR 2 500.

We have chosen products at a level that we believe provides the accuracy, reliability, and security required. The type of sensor that we recommend to caterers and commercial kitchens are based on semiconductor technology combined with a patented method, called GSS, providing excellent reliability and safe operation. The special technique used makes the sensor very precise and in many cases comparable to the UV technic. Therefore, they can be used in many cases where you want a safe and reliable measurement but where a UV photometer is simply too expensive.

It is important to know what technology the sensor manufacturer uses and also how their instruments are calibrated. When it comes to measurements in the low range, as for occupational exposure limits specified in local regulations for safety in the workplace, it is important that the sensor is calibrated for that span and that the calibration is NIST-traceable. Traceability is designed to ensure that you used the correct reference points. It is also important that each sensor is supplied with a calibration certificate because each measuring instrument must be checked and calibrated uniquely.

Another important aspect is the quality of the sensor; for how long does it show correct readings? Many manufacturers nowadays offer very inexpensive sensors which may seem attractive at first glance. However, this can be a dangerous saving because it is impossible to say for how long the sensor element detects correct values.

The risks associated with an inadequate sensor can have serious consequences since the main aim is to ensure a safe and secure work environment. A sensor that does not measure up, technical or in quality, will be the weak link in your safety systems.

The most fundamental questions that each supplier of measuring instruments and sensors should be able to offer/answer are:

  • Individual calibration certificate per module
  • NIST-traceability, against which reference and how often the reference is calibrated
  • Operating time
  • Comparison with the reference technology (usually UV)
  • How do you notice when it is time to replace elements or recalibrate?
  • Is it an active or passive measurement? How is the baseline value ensured at each measurement?
  • Response time

Noise Regulations in Public Areas

According to recommendations from e.g. the Swedish Work Environment Authority, sound level of equipment for use in commercial kitchens and restaurants should not to exceed 50 dBA in order to maintain a good working environment for the staff.

Both our ICT- and FTX- series meets the requirements of <50 dBA. This is not the case for all manufacturers; some similar units displays noise levels of 70 dBA and above.

There are good reasons why the regulations have implemented acoustic requirements (noise requirements) for the workplace. Effects such as fatigue, irritability, accidents and stress can be linked to noise exposure. Monotonous and low-frequency sound, even at moderate levels, has a negative impact on people in the room.

Example of noise regulations:
  • 70 dB(A) – Conversation with loud voice can barely be held at a 1 m distance with other people with perfect hearing
  • 55 dB(A) – The environment required for effective voice communication in a normal voice in close proximity from the speaker
  • 50 dB(A) – The environment required for effective voice communication in a normal voice at 5 -10 m (15-30 ft) from the speaker


Noise Regulation for Indoor*
For more detailed information, contact your local Work Environment Authority.

Maximum noise level: The stated values must be attained in all zones frequented by people, but not closer than 1 m from the noise source. The values indoor are valid at 10 m2 equivalent absorption area. A 5 dB higher level is allowed for single sound impulses.

Type of Area Max sound level LA (dB) at 10 m2 equivalent absorption area
Daycare facilities (common areas, group rooms etc) 30 dBA
Malls 35 dBA
Dining rooms 35 dBA
Offices 35 dBA
Staff areas, hallways etc 35 dBA
Toilets, supply rooms etc 40 dBA
Commercial kitchens, garbage rooms 50 dBA


* Examples and noise levels are based on Swedish Work Environment Authorities recommendations according to AFS 2005:16.

Chimney Sweeping

The ventilation system in a kitchen serves to dissipate heat, moisture, fat, cooking fumes and to provide fresh air supply.

Fat (fumes) is the number one enemy in a restaurant kitchen. Grease is flammable, burning at high temperatures and can lead to large, difficult to extinguish fires. Consequently, all exhaust ducts in restaurant and catering kitchens are regularly cleaned.

The chimney sweeping process depends on system. Typically the duct, fan and ventilation unit is sprayed with hot water and grease solvent to remove flammable fat deposits.

The sweeping interval of exhaust ducts are determined by the local municipality and usually regulated by the safety/fire code in order to prevent chimney and kitchen flue fires.

About Ozone

Download information about ozone as pdf

Why Use Ozone in Commercial Kitchens

  • Ozone efficiently removes fat and odors
  • It treats the entire duct length quick and cost-efficiently
  • Easy to install and operate

Ozone can be regarded as a chemical scissors; an effective one that rapidly “cuts” long unwanted grease and odor molecules.


Ozone in Commercial Kitchens

What is Ozone?

Ozone is a powerful oxidizing agent. It is soluble in water with a very good ability to eliminate microorganisms, grease and pollutants. Ozone reacts with other substances in its surrounding and it is this characteristic that we use in our systems.

When an ozone molecule collides with another substance, such as odors, it breaks it down into smaller components which are less prone to cause problems. The by-products after this reaction are usually carbon dioxide, water and fat ash/dust. Ozone that is not used during the process returns to regular oxygen.

Ozone also has the ability to eliminate microorganisms such as bacteria and viruses. A reaction between ozone and bacteria damages the cell structure and causes the microbiological activity to cease.

Ozone


How is Ozone Produced?

Ozone naturally occurs in our environment and in the air. It is formed when oxygen, consisting of two oxygen atoms, is subjected to energy from lightning or UV rays.

These processes are mimicked in purification systems using ozone by allowing oxygen atoms to pass an electric field (corona discharge) or UV light and then directing the ozone to the treatment area.

The method to produce ozone differs between manufacturers. Read more about our technology.




Ozone Production

To produce small amounts of ozone for a short while is easy. An electric spark in the air is enough. The challenge lies in keeping a constant ozone production for several years. If the flow over the ozone element isn’t completely clean, pollutants are rapidly formed which decrease the ozone production. Picture an engine stalling due to soot build up.

If you are about to choose an air purification system, it is important to know that the method used to produce ozone plays a huge role in the final result – measured over several years.


Ozone Production Factors that affect the amount of ozone produced, as well as the concentration are:

  • The amount and concentration of oxygen that passes over the ozone elements – the more, the better
  • Pressure – the higher, the better
  • Temperature – the lower, the better
  • The design of the electric field
  • The way ozone elements are linked together – parallel beneficial / in series detrimental


Factors that affect the lifespan of the equipment are:

  • Oxygen purity over the ozone elements
  • Nitrogen content of ozone elements
  • The environment and the purity in which ozone is formed
  • Humidity in the supply air / oxygen
  • Cooling of ozone elements and electronics
  • The right material in the machine


Industrial applications put high demands on equipment and machinery. High reliability and constant production are obvious requirements. Given our objective and the technical challenges that exist in air purification, we have chosen to use compact high-performance ozone systems developed for industrial applications for exhaust flows of 2,500 m3/h and above.

Read more about the 20 things to consider to succeed.

Ozone is formed from oxygen passing through a high voltage field. Efficient cooling is a key design parameter.

Oxygen Source

The oxygen source is very important for how “clean” the produced ozone is. Or rather, how free from unwanted byproducts the gas is.

If the oxygen source for ozone production is common supply air, it will contain approximately 78% nitrogen and water vapor.

However, if an oxygen generator is used the oxygen source will be 93% oxygen, 7% nitrogen and completely dry. This minimizes problems with nitrous acid (formed by nitrogen oxide and water vapor) and ammonium nitrate.


The advantage of a pure oxygen source is that it maximizes the purification capacity (the amount of ozone), minimizes the amount of harmful byproducts and contributes greatly to high operation reliability.
 

Cooling

The cooling is central to the system’s efficiency, size and reliability. A cooler environment leads to a better ozone production and a better environment for the electronics. Unfortunately, it is inevitable that heat is produced in the ozone production process. The heat must be dissipated to avoid reduced ozone production or even overheating.


Liquid cooling systems are significantly more efficient than air. You can use central cooling, closed cooling systems or tap water. The advantage is that it allows for a fantastic ozone production while system reliability is considerably better than air-cooled systems.

Material Safety Data Sheet – Ozone (O3)

Download Safety Datasheet as pdf

General Data

Product/material Ozone
Molecular formula O3
Principal characteristics Oxidising gas – CAS no. 10028-15-6 / EG no. 233-069-2
Molecular weight 48.0
Production Corona discharge
Concentration Up to 18 % by weight in oxygen/oxygen-enriched air
Boiling point -111.0°C
Melting point -192.7°C
Solubility in water by weight (at 20°C) 0.003 g/l (3 ppm)
Vapour densitiy 1.6 (1 = air)
Flammability Non-flammable/vigorously supports combustion
Appearance and odour Ozone is colourless at all concentrations experianced in the industry. It has a pungent characteristics odour usually associated with electrical sparks. The odour is generally detectable by the human nose at concentrations of 0.02 and 0.05 ppm. Fire/Explosion and hazard data Ozone is a powerful oxidising agent. Oxidation with ozone evolves more heat and usually ignites at a lower temperature than oxidising with oxygen. Ozone reacts with non-saturated organic compounds to produce ozonides, which are unstable and may decompose with explosive voilence. Ozone is an unstable gas that, at normal temperatures, decomposes to biatomic oxygen. At elevated temperatures and in presence of certain catalysts such as hydrogen, iron, copper and chromium, this decomposition may be explosive. Flash point Not applicable Auto ignition temperature Not applicable


Reaction Data

Conditions contributing to instability Ozone spontanenously decomposes under all ordinary conditions, so that is not normally encountered except in the immidiate vicinity of its production. Decomposition is accelerated by contact with solid surfaces, by contact with chemical substances and by the effect of heat.
Incompatibilities Ozone is a power oxidising agent and reacts with all oxidising materials, both organic and inorganic. Some reaction products are highly explosive.
Hazardous decomposition products None


Health Hazard Data

Permissible Exposure Limits The following limits are widly accepted (USA, Sweden and other parts of Europe): – 8 hour per day/5 days per week (occupational exposure limit) – 0.1 ppm – 15 minutes (short term exposure limit) – 0.3 ppm
Toxicology of ozone The acute and chronic effects of excessive exposure to ozone have been well investigated. Exposure to concentrations of ozone in excess of several tenths of a ppm sometime cause reports of discomfort in a small susceptible portion of the population. This can be in the form of headaches of dryness of the throat and mucous membranes of the eyes and nose following exposures of short duration. Repeated exposure to ozone at such concentrations at 24-hour intervals, however, caused no further increase in airway irritability. In fact after the first exposures, additional exposures to ozone had progressively lesser effects suggesting that tolerance may develop over time. Ozone has been shown to be more injurious at concentrations exceeding 2.0ppm over several hours, such as experienced by gas shielded arv welders. The primary site of acute effects is the lung which is characterized by pulmonary congestion. This acute impact subsided in welders when exposures where reduced to less than 0.2ppm. Based on animal studies, exposure over 10 to 20ppm or an hour or less believed to be lethal in humans although there has never been a single recorded fatality attributed to ozone exposure in more than 100 years of commercial use. (Compare with this experience with Chlorine as which has claimed many victims in peacetime as well as during war). With respect to long term or chronic toxicity, ozone is a radiomimetic agent, i.e. the effects of long term exposure to excessive ozone exhibits the same affects as excessive exposure to sunlight. These effects are drying of the dermal surfaces and general ageing of exposed tissues. Ozone is not generally regarded or suspected of being a human carcinogen, neither does in exhibit tertogenic or mutagenic properties. In the event of an ozone leak:
  1. Ventilate the area
  2. Immediately switch the ozone generator off
  3. Stop the flow of ozonated water
  4. Where high levels of ozone are experienced (in excess of 0.1ppm) all personnel should vacate the affected area until it has been thoroughly ventilated
  5. When ozone levels in excess of 0.3ppm are present, or when personnel are required to work in restricted spaces or tanks, where ozone my be present, only persons wearing suitable breathing apparatus should be allowed in the area and the appropriate safe working practices for confined areas should be applied
Disposal of waste ozone gas It is accepted practice, and required by statute in some jurisdictions, that Ozone gas should not be released into the atmosphere but should be destroyed using an approved ozone destruction method. (Catalytic, thermal, or absorption).
Disposal of waste ozone gas All potential outlets of ozone gas into the occupied areas or external atmosphere should be identified.
  1. All routine operational releases of ozone to the occupied areas or external atmosphere should be contained and passed through an ozone destruction system (as above)
  2. All occupied areas where ozone is generated or applied should be provide with an effective ventilation system commensurate with the rate of ozone production and other risk factors
  3. All occupied areas where ozone is generated or applied should be provide with an effective ventilation system commensurate with the rate of ozone production and other risk factors
  4. Where ozone is applied to liquids It is important to consider that ozone will escape from solutions under most conditions. Precautions include: ensuring that all vessels containing ozonated liquids are air-tight or under negative pressure to prevent escape of ozone. Any vents where ozone might escape should be connected to an ozone destruction system. Where ozonated liquids, such as used rinse water, are discharged this should be via close pipe work to close drains
Disposal of waste ozone gas
  • Eye exposure – If ozone gets into the eyes, wash immediately with large amount of water, lifting the upper and lower eye lids occasionally. Seek medical attention as soon as possible
  • Breathing – If a person breaths in large amounts of ozone, move the person into warm un-contaminated air at once. If breathing has stopped, perform artificial respiration. When breathing is difficult, properly trained personnel may assist by administering breathing oxygen. Keep the affected person war and at res. Seek medical attention as soon as possible
  • Rescue – Move the affected person to safety. If the person has been overcome notify somebody else and put into effect the established emergency procedures. Do not enter the affected area without assistance or against the advice of the recommended safety procedures as they may apply at each facility
Ozone Tech Systems OTS AB shall not be liable for any loss or damage of any nature whatsoever, however arising, relating to the use or handling of ozone or statements contained in or omitted from this document.